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Gastrotrich

The gastrotrichs (phylum Gastrotricha), commonly referred to as hairybellies or hairybacks, are a group of microscopic (0.06–3.0 mm), cylindrical, acoelomate animals, and are widely distributed and abundant in freshwater and marine environments. They are mostly benthic and live within the periphyton, the layer of tiny organisms and detritus that is found on the seabed and the beds of other water bodies. The majority live on and between particles of sediment or on other submerged surfaces, but a few species are terrestrial and live on land in the film of water surrounding grains of soil. Gastrotrichs are divided into two orders, the Macrodasyida which are marine (except for two species), and the Chaetonotida, some of which are marine and some freshwater. Nearly 800 species of gastrotrich have been described.

Gastrotrichs have a simple body plan with a head region, with a brain and sensory organs, and a trunk with a simple gut and the reproductive organs. They have adhesive glands with which they can anchor themselves to the substrate and cilia with which they move around. They feed on detritus, sucking up organic particles with their muscular pharynx. They are hermaphrodites, the marine species producing eggs which develop directly into miniature adults. The freshwater species are parthenogenetic, producing unfertilised eggs, and at least one species is viviparous. Gastrotrichs mature with great rapidity and have lifespans of only a few days.

Etymology and taxonomy
The name "gastrotrich" comes from the Greek γαστήρ gaster, meaning "stomach", and θρίξ thrix, meaning "hair". The name was coined by the Russian zoologist Élie Metchnikoff in 1865. The common name "hairyback" apparently arises from a mistranslation of "gastrotrich".

The relationship of gastrotrichs to other phyla is unclear. Morphology suggests that they are close to the Gnathostomulida, the Rotifera, or the Nematoda. On the other hand, genetic studies place them as close relatives of the Platyhelminthes, the Ecdysozoa or the Lophotrochozoa. As of 2011, around 790 species have been described. The phylum contains a single class, divided into two orders: the Macrodasyida and the Chaetonotida. Edward Ruppert et al. report that the Macrodasyida are wholly marine, but two rare and poorly known species, Marinellina flagellata and Redudasys fornerise, are known from fresh water. The Chaetonotida comprises both marine and freshwater species.

Anatomy
Gastrotrichs vary in size from about 0.06 to 3 mm in body length. They are bilaterally symmetrical, with a transparent strap-shaped or bowling pin-shaped body, arched dorsally and flattened ventrally. The anterior end is not clearly defined as a head but contains the sense organs, brain and pharynx. Cilia are found around the mouth and on the ventral surface of the head and body. The trunk contains the gut and the reproductive organs. At the posterior end of the body are two projections with cement glands that serve in adhesion. This is a double-gland system where one gland secretes the glue and another secretes a de-adhesive agent to sever the connection. In the Macrodasyida, there are additional adhesive glands at the anterior end and on the sides of the body.

The body wall consists of a cuticle, an epidermis and longitudinal and circular bands of muscle fibres. In some primitive species, each epidermal cell has a single cilium, a feature shared only by the gnathostomulans. The whole ventral surface of the animal may be ciliated or the cilia may be arranged in rows, patches or transverse bands. The cuticle is locally thickened in some gastrotrichs and forms scales, hooks and spines. There is no coelom (body cavity) and the interior of the animal is filled with poorly differentiated connective tissue. In the macrodasyidans, Y-shaped cells, each containing a vacuole, surround the gut and may function as a hydrostatic skeleton.

The mouth is at the anterior end and opens into an elongated muscular pharynx with a triangular or Y-shaped lumen, lined by myoepithelial cells. The pharynx opens into a cylindrical intestine, which is lined with glandular and digestive cells. The anus is located on the ventral surface close to the posterior of the body. In some species, there are pores in the pharynx opening to the ventral surface; these contain valves and may allow egestion of any excess water swallowed while feeding.

In the chaetonotidans, the excretory system consists of a single pair of protonephridia, which open through separate pores on the lateral underside of the animal, usually in the midsection of the body. In the macrodasyidans, there are several pairs of these opening along the side of the body. Nitrogenous waste is probably excreted through the body wall, as part of respiration, and the protonephridia are believed to function mainly in osmoregulation. Unusually, the protonephridia do not take the form of flame cells, but, instead, the excretory cells consist of a skirt surrounding a series of cytoplasmic rods that in turn enclose a central flagellum. These cells, termed cyrtocytes, connect to a single outlet cell which passes the excreted material into the protonephridial duct.

As is typical for such small animals, there are no respiratory or circulatory organs. The nervous system is relatively simple. The brain consists of two ganglia, one on either side of the pharynx, connected by a commissure. From these lead a pair of nerve cords which run along either side of the body beside the longitudinal muscle bands. The primary sensory organs are the bristles and ciliated tufts of the body surface which function as mechanoreceptors. There are also ciliated pits on the head, simple ciliary photoreceptors and fleshy appendages which act as chemoreceptors.

Distribution and habitat
Gastrotrichs are cosmopolitan in distribution. They inhabit the interstitial spaces between particles in marine and freshwater environments, the surfaces of aquatic plants and other submerged objects and the surface film of water surrounding soil particles on land. They are also found in stagnant pools and anaerobic mud, where they thrive even in the presence of hydrogen sulfide. When pools dry up they can survive periods of desiccation as eggs, and some species are capable of forming cysts in harsh conditions. In marine sediments they have been known to reach 364 individuals per 10 cm2 making them the third most common invertebrate in the sediment after nematodes and harpacticoid copepods. In freshwater they may reach a density of 158 individuals per 10 cm2 and are the fifth most abundant group of invertebrates in the sediment.

Behaviour and ecology
In marine and freshwater environments, gastrotrichs form part of the benthic community. They are detritivores and are microphagous: they feed by sucking small dead or living organic materials, diatoms, bacteria and small protozoa into their mouths by the muscular action of the pharynx. They are themselves eaten by turbellarians and other small macrofauna.

Like many microscopic animals, gastrotrich locomotion is primarily powered by hydrostatics, but movement occurs through different methods in different members of the group. Chaetonotids only have adhesive glands at the back and, in them, locomotion typically proceeds in a smooth gliding manner; the whole body is propelled forward by the rhythmic action of the cilia on the ventral surface. In the pelagic chaetonotid genus Stylochaeta, however, movement proceeds in jerks as the long, muscle-activated spines are forced rhythmically towards the side of the body. By contrast, with chaetonotids, macrodasyidans typically have multiple adhesive glands and move forward with a creeping action similar to that of a "looper" caterpillar. In response to a threat, the head and trunk can be rapidly pulled backwards, or the creeping movement can be reversed. Muscular action is important when the animal turns sideways and during copulation, when two individuals twine around each other.

Reproduction and lifespan
Gastrotrich reproduction and reproductive behaviour has been little studied. That of macrodasiyds probably most represents that of the ancestral lineage and these more primitive gastrotrichs are simultaneous hermaphrodites, possessing both male and female sex organs. There is generally a single pair of gonads, the anterior portion of which contains sperm-producing cells and the posterior portion producing ova. The sperm is sometimes packaged in spermatophores and is released through male gonopores that open, often temporarily, on the underside of the animal, roughly two-thirds of the way along the body. A copulatory organ on the tail collects the sperm and transfers it to the partner's seminal receptacle through the female gonopore. Details of the process and the behaviour involved vary with the species, and there is a range of different accessory reproductive organs. During copulation, the "male" individual uses his copulatory organ to transfer sperm to his partner's gonopore and fertilisation is internal. The fertilised eggs are released by rupture of the body wall which afterwards repairs itself. As is the case in most protostomes, development of the embryo is determinate, with each cell destined to become a specific part of the animal's body. At least one species of gastrotrich, Urodasys viviparus, is viviparous.

Many species of chaetotonid gastrotrichs reproduce entirely by parthenogenesis. In these species, the male portions of the reproductive system are degenerate and non-functional, or, in many cases, entirely absent. Though the eggs have a diameter of less than 50 μm, they are still very large in comparison with the animals' size. Some species are capable of laying eggs that remain dormant during times of desiccation or low temperatures; these species, however, are also able to produce regular eggs, which hatch in one to four days, when environmental conditions are more favourable. The eggs of all gastrotrichs undergo direct development and hatch into miniature versions of the adult. The young typically reach sexual maturity in about three days. In the laboratory, Lepidodermella squamatum has lived for up to forty days, producing four or five eggs during the first ten days of life.

Gastrotrichs demonstrate eutely, each species having an invariant genetically fixed number of cells as adults. Cell division ceases at the end of embryonic development and further growth is solely due to cell enlargement.

Classification
Gastrotricha is divided into two orders and a number of families:

Order Macrodasyida Remane, 1925 [Rao and Clausen, 1970]
 * Family Cephalodasyidae Hummon & Todaro, 2010
 * Genus Cephalodasys Remane, 1926
 * Genus Dolichodasys Gagne, 1977
 * Genus Megadasys Schmidt, 1974
 * Genus Mesodasys Remane, 1951
 * Genus Paradasys Remane, 1934
 * Genus Pleurodasys Remane, 1927

 * Family Dactylopodolidae Strand, 1929
 * Genus Dactylopodola Strand, 1929
 * Genus Dendrodasys Wilke, 1954
 * Genus Dendropodola Hummon, Todaro & Tongiorgi, 1992

 * Family Lepidodasyidae Remane, 1927
 * Genus Lepidodasys Remane, 1926

 * Family Macrodasyidae Remane, 1926
 * Genus Macrodasys Remane, 1924
 * Genus Urodasys Remane, 1926

 * Family Planodasyidae Rao & Clausen, 1970
 * Genus Crasiella Clausen, 1968
 * Genus Planodasys Rao & Clausen, 1970

 * Family Redudasyidae Todaro, Dal Zotto, Jondelius, Hochberg et al., 2012
 * Genus Anandrodasys Todaro, Dal Zotto, Jondelius, Hochberg et al., 2012
 * Genus Redudasys Kisielewski, 1987

 * Family Thaumastodermatidae Remane, 1927
 * Subfamily Diplodasyinae Ruppert, 1978
 * Genus Acanthodasys Remane, 1927
 * Genus Diplodasys Remane, 1927
 * Subfamily Thaumastodermatinae Remane, 1927
 * Genus Hemidasys Claparède, 1867
 * Genus Oregodasys Hummon, 2008 =(Platydasys Remane, 1927)
 * Genus Pseudostomella Swedmark, 1956
 * Genus Ptychostomella Remane, 1926
 * Genus Tetranchyroderma Remane, 1926
 * Genus Thaumastoderma Remane, 1926
 * Family Turbanellidae Remane, 1927
 * Genus Desmodasys Clausen, 1965
 * Genus Dinodasys Remane, 1927
 * Genus Paraturbanella Remane, 1927
 * Genus Prostobuccantia Evans & Hummon, 1991
 * Genus Pseudoturbanella d'Hondt, 1968
 * Genus Turbanella Schultze, 1853

 * Family Xenodasyidae Todaro, Guidi, Leasi & Tongiorgi, 2006
 * Genus Chordodasiopsis Todaro, Guidi, Leasi & Tongiorgi, 2006
 * Genus Xenodasys Swedmark, 1967

 * Incertae sedis
 * Genus Marinellina Ruttner-Kolisko, 1955

Order Chaetonotida Remane, 1925 [Rao and Clausen, 1970]

Suborder Multitubulatina d'Hondt, 1971
 * Family Neodasyidae Remane, 1929
 * Genus Neodasys Remane, 1927

Suborder Paucitubulatina d'Hondt, 1971
 * Family Chaetonotidae Gosse, 1864
 * Subfamily Chaetonotinae Kisielewski, 1991
 * Genus Arenotus Kisielewski, 1987
 * Genus Aspidiophorus Voigt, 1903
 * Genus Caudichthydium Schwank, 1990
 * Genus Chaetonotus Ehrenberg, 1830
 * Genus Fluxiderma d'Hondt, 1974
 * Genus Ichthydium Ehrenberg, 1830
 * Genus Halichaetonotus Remane, 1936
 * Genus Heterolepidoderma Remane, 1927
 * Genus Lepidochaetus Kisielewski 1991
 * Genus Lepidodermella Blake, 1933
 * Genus Polymerurus Remane, 1927
 * Genus Rhomballichthys Schwank, 1990
 * Subfamily Undulinae Kisielewski 1991
 * Genus Undula Kisielewski 1991
 * Family Dasydytidae Daday, 1905
 * Genus Anacanthoderma Marcolongo, 1910
 * Genus Chitonodytes Remane, 1936
 * Genus Dasydytes Gosse, 1851
 * Genus Haltidytes Remane 1936
 * Genus Ornamentula Kisielewski 1991
 * Genus Setopus Grünspan, 1908
 * Genus Stylochaeta Hlava, 1905

 * Family Dichaeturidae Remane, 1927
 * Genus Dichaetura Lauterborn, 1913

 * Family Muselliferidae Leasi & Todaro, 2008
 * Genus Diuronotus Todaro, Kristensen & Balsamo, 2005
 * Genus Musellifer Hummon, 1969

 * Family Neogosseidae Remane, 1927
 * Genus Neogossea Remane, 1927
 * Genus Kijanebalola Beauchamp, 1932

 * Family Proichthydiidae Remane, 1927
 * Genus Proichthydium Cordero, 1918
 * Genus Proichthydioides Sudzuki, 1971

 * Family Xenotrichulidae Remane, 1927
 * Subfamily Draculiciterinae Ruppert, 1979
 * Genus Draculiciteria Hummon, 1974
 * Subfamily Xenotrichulinae Remane, 1927
 * Genus Heteroxenotrichula Wilke, 1954
 * Genus Xenotrichula Remane, 1927

title: Gastrotrich


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Hemichordate

Hemichordata is a phylum which consists of triploblastic, enterocoelomate, and bilaterally symmetrical marine deuterostome animals, generally considered the sister group of the echinoderms. They appear in the Lower or Middle Cambrian and include two main classes: Enteropneusta (acorn worms), and Pterobranchia. A third class, Planctosphaeroidea, is known only from the larva of a single species, Planctosphaera pelagica. The class Graptolithina, formerly considered extinct, is now placed within the pterobranchs, represented by a single living genus Rhabdopleura.

Acorn worms are solitary worm-shaped organisms. They generally live in burrows (the earliest secreted tubes) and are deposit feeders, but some species are pharyngeal filter feeders, while the family Torquaratoridae are free living detritivores. Many are well known for their production and accumulation of various halogenated phenols and pyrroles. Pterobranchs are filter-feeders, mostly colonial, living in a collagenous tubular structure called a coenecium.

The discovery of the stem group hemichordate Gyaltsenglossus shows that early hemichordates combined aspects of the two morphologically disparate classes.

Anatomy
The body plan of hemichordates is characterized by a muscular organization. The anteroposterior axis is divided into three parts: the anterior prosome, the intermediate mesosome, and the posterior metasome.

The body of acorn worms is worm-shaped and divided into an anterior proboscis, an intermediate collar, and a posterior trunk. The proboscis is a muscular and ciliated organ used in locomotion and in the collection and transport of food particles. The mouth is located between the proboscis and the collar. The trunk is the longest part of the animal. It contains the pharynx, which is perforated with gill slits (or pharyngeal slits), the oesophagus, a long intestine, and a terminal anus. It also contains the gonads. A post-anal tail is present in juvenile member of the acorn worm family Harrimaniidae.

The prosome of pterobranchs is specialized into a muscular and ciliated cephalic shield used in locomotion and in secreting the coenecium. The mesosome extends into one pair (in the genus Rhabdopleura) or several pairs (in the genus Cephalodiscus) of tentaculated arms used in filter feeding. The metasome, or trunk, contains a looped digestive tract, gonads, and extends into a contractile stalk that connects individuals to the other members of the colony, produced by asexual budding. In the genus Cephalodiscus, asexually produced individuals stay attached to the contractile stalk of the parent individual until completing their development. In the genus Rhabdopleura, zooids are permanently connected to the rest of the colony via a common stolon system.

They have a diverticulum of the foregut called a stomochord, previously thought to be related to the chordate notochord, but this is most likely the result of convergent evolution rather than a homology. A hollow neural tube exists among some species (at least in early life), probably a primitive trait that they share with the common ancestor of chordata and the rest of the deuterostomes. Hemichordates have a nerve net and longitudinal nerves, but no brain.

Some species biomineralize in calcium carbonate.

Circulatory system
Hemichordates have an open circulatory system. The heart vesicle is located dorsally within the proboscis complex, and does not contain any blood. Instead it moves the blood indirectly by pulsating against the dorsal blood vessel.

Development
Together with the Echinoderms, the hemichordates form the Ambulacraria, which are the closest extant phylogenetic relatives of chordates. Thus these marine worms are of great interest for the study of the origins of chordate development. There are several species of hemichordates, with a moderate diversity of embryological development among these species. Hemichordates are classically known to develop in two ways, both directly and indirectly. Hemichordates are a phylum composed of two classes, the enteropneusts and the pterobranchs, both being forms of marine worm.

The enteropneusts have two developmental strategies: direct and indirect development. The indirect developmental strategy includes an extended pelagic plankotrophic tornaria larval stage, which means that this hemichordate exists in a larval stage that feeds on plankton before turning into an adult worm. The Pterobranch genus most extensively studied is Rhabdopleura from Plymouth, England and from Bermuda.

The following details the development of two popularly studied species of the hemichordata phylum Saccoglossus kowalevskii and Ptychodera flava. Saccoglossus kowalevskii is a direct developer and Ptychodera flava is an indirect developer. Most of what has been detailed in Hemichordate development has come from hemichordates that develop directly.

Ptychodera flava
P. flava’s early cleavage pattern is similar to that of S. kowalevskii. The first and second cleavages from the single cell zygote of P. flava are equal cleavages, are orthogonal to each other and both include the animal and vegetal poles of the embryo. The third cleavage is equal and equatorial so that the embryo has four blastomeres both in the vegetal and the animal pole. The fourth division occurs mainly in blastomeres in the animal pole, which divide transversally as well as equally to make eight blastomeres. The four vegetal blastomeres divide equatorially but unequally and they give rise to four big macromeres and four smaller micromeres. Once this fourth division has occurred, the embryo has reached a 16 cell stage. P. flava has a 16 cell embryo with four vegetal micromeres, eight animal mesomeres and 4 larger macromeres. Further divisions occur until P. flava finishes the blastula stage and goes on to gastrulation. The animal mesomeres of P. flava go on to give rise to the larva’s ectoderm, animal blastomeres also appear to give rise to these structures though the exact contribution varies from embryo to embryo. The macromeres give rise to the posterior larval ectoderm and the vegetal micromeres give rise to the internal endomesodermal tissues. Studies done on the potential of the embryo at different stages have shown that at both the two and four cell stage of development P. flava blastomeres can go on to give rise to a tornaria larvae, so fates of these embryonic cells don’t seem to be established till after this stage.

Saccoglossus kowalevskii
Eggs of S. kowalevskii are oval in shape and become spherical in shape after fertilization. The first cleavage occurs from the animal to the vegetal pole and usually is equal though very often can also be unequal. The second cleavage to reach the embryos four cell stage also occurs from the animal to the vegetal pole in an approximately equal fashion though like the first cleavage it’s possible to have an unequal division. The eight cell stage cleavage is latitudinal; so that each cell from the four cell stage goes on to make two cells. The fourth division occurs first in the cells of the animal pole, which end up making eight blastomeres (mesomeres) that are not radially symmetric, then the four vegetal pole blastomeres divide to make a level of four large blastomeres (macromeres) and four very small blastomeres (micromeres). The fifth cleavage occurs first in the animal cells and then in the vegetal cells to give a 32 cell blastomere. The sixth cleavage occurs in a similar order and completes a 64 cell stage, finally the seventh cleavage marks the end of the cleavage stage with a blastula with 128 blastomeres. This structure goes on to go through gastrulation movements which will determine the body plan of the resulting gill slit larva, this larva will ultimately give rise to the marine acorn worm.

Genetic control of dorsal-ventral hemichordate patterning
Much of the genetic work done on hemichordates has been done to make comparison with chordates, so many of the genetic markers identified in this group are also found in chordates or are homologous to chordates in some way. Studies of this nature have been done particularly on S. kowalevskii, and like chordates S. kowalevskii has dorsalizing bmp-like factors such as bmp 2/4, which is homologous to Drosophila’s decapentaplegic dpp. The expression of bmp2/4 begins at the onset of gastrulation on the ectodermal side of the embryo, and as gastrulation progresses its expression is narrowed down to the dorsal midline but is not expressed in the post anal tail. The bmp antagonist chordin is also expressed in the endoderm of gastrulating S. kowalevskii. Besides these well known dorsalizing factors, further molecules known to be involved in dorsal ventral patterning are also present in S. kowalevskii, such as a netrin that groups with netrin gene class 1 and 2. Netrin is important in patterning of the neural system in chordates, as well as is the molecule Shh, but S. kowalevskii was only found to have one hh gene and it appears to be expressed in a region that is uncommon to where it is usually expressed in developing chordates along the ventral midline.

Classification

Hemichordata are divided into two classes: the Enteropneusta, commonly called acorn worms, and the Pterobranchia, which includes the graptolites. A third class, Planctosphaeroidea, is proposed based on a single species known only from larvae. The phylum contains about 120 living species. Hemichordata appears to be sister to the Echinodermata as Ambulacraria; Xenoturbellida may be basal to that grouping. Pterobranchia may be derived from within Enteropneusta, making Enteropneusta paraphyletic. It is possible that the extinct organism Etacystis is a member of the Hemichordata, either within or with close affinity to the Pterobranchia.

There are 130 described species of Hemichordata and many new species are being discovered, especially in the deep sea.

Phylogeny
A phylogenetic tree showing the position of the hemichordates is:

The internal relationships within the hemichordates are shown below. The tree is based on 16S +18S rRNA sequence data and phylogenomic studies from multiple sources.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Hemichordate


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Acanthocephala

Acanthocephala (Greek ἄκανθος, akanthos 'thorn' + κεφαλή, kephale 'head') is a group of parasitic worms known as acanthocephalans, thorny-headed worms, or spiny-headed worms, characterized by the presence of an eversible proboscis, armed with spines, which it uses to pierce and hold the gut wall of its host. Acanthocephalans have complex life cycles, involving at least two hosts, which may include invertebrates, fish, amphibians, birds, and mammals. About 1420 species have been described.

The Acanthocephala were thought to be a discrete phylum. Recent genome analysis has shown that they are descended from, and should be considered as, highly modified rotifers. This unified taxon is sometimes known as Syndermata, but are also described as a subclass of Hemirottoriod rotifera.

History
The earliest recognisable description of Acanthocephala – a worm with a proboscis armed with hooks – was made by Italian author Francesco Redi (1684). In 1771, Joseph Koelreuter proposed the name Acanthocephala. Philipp Ludwig Statius Müller independently called them Echinorhynchus in 1776. Karl Rudolphi in 1809 formally named them Acanthocephala.

Evolutionary history
The oldest known remains of acanthocephalans are eggs found in a coprolite from the Late Cretaceous Bauru Group of Brazil, around 70-80 million years old, likely from a crocodyliform. The group may have originated substantially earlier.

Phylogeny
Acanthocephalans are highly adapted to a parasitic mode of life, and have lost many organs and structures through evolutionary processes. This makes determining relationships with other higher taxa through morphological comparison problematic. Phylogenetic analysis of the 18S ribosomal gene has revealed that the Acanthocephala are most closely related to the rotifers. They are possibly closer to the two rotifer classes Bdelloidea and Monogononta than to the other class, Seisonidea, producing the names and relationships shown in the cladogram below.

The three rotifer classes and the Acanthocephala make up a clade called Syndermata. This clade is placed in the Gnathifera.

A study of the gene order in the mitochondria suggests that Seisonidea and Acanthocephala are sister clades and that the Bdelloidea are the sister clade to this group.

Currently the phylum is divided into four classes – Palaeacanthocephala, Archiacanthocephala, Polyacanthocephala and Eoacanthocephala. The monophyletic Archiacanthocephala are the sister taxon of a clade comprising Eoacanthocephala and the monophyletic Palaeacanthocephala.

Morphology

Several morphological characteristics distinguish acanthocephalans from other phyla of parasitic worms.

Digestion
Acanthocephalans lack a mouth or alimentary canal. This is a feature they share with the cestoda (tapeworms), although the two groups are not closely related. Adult stages live in the intestines of their host and uptake nutrients which have been digested by the host, directly, through their body surface. The acanthocephalans lack an excretory system, although some species have been shown to possess flame cells (protonephridia).

Proboscis

The most notable feature of the acanthocephala is the presence of an anterior, protrudable proboscis that is usually covered with spiny hooks (hence the common name: thorny or spiny headed worm). The proboscis bears rings of recurved hooks arranged in horizontal rows, and it is by means of these hooks that the animal attaches itself to the tissues of its host. The hooks may be of two or three shapes, usually: longer, more slender hooks are arranged along the length of the proboscis, with several rows of more sturdy, shorter nasal hooks around the base of the proboscis. The proboscis is used to pierce the gut wall of the final host, and hold the parasite fast while it completes its life cycle.

Like the body, the proboscis is hollow, and its cavity is separated from the body cavity by a septum or proboscis sheath. Traversing the cavity of the proboscis are muscle-strands inserted into the tip of the proboscis at one end and into the septum at the other. Their contraction causes the proboscis to be invaginated into its cavity. The whole proboscis apparatus can also be, at least partially, withdrawn into the body cavity, and this is effected by two retractor muscles which run from the posterior aspect of the septum to the body wall.

Some of the acanthocephalans (perforating acanthocephalans) can insert their proboscis in the intestine of the host and open the way to the abdominal cavity.

Size
The size of these animals varies greatly, some are measured to be a few millimetres in length to Macracanthorhynchus hirudinaceus, which measures from 10 to 65 cm. A curious feature shared by both larva and adult is the large size of many of the cells, e.g. the nerve cells and cells forming the uterine bell. Polyploidy is common, with up to 343n having been recorded in some species.

Skin
The body surface of the acanthocephala is peculiar. Externally, the skin has a thin tegument covering the epidermis, which consists of a syncytium with no cell walls. The syncytium is traversed by a series of branching tubules containing fluid and is controlled by a few wandering, amoeboid nuclei. Inside the syncytium is an irregular layer of circular muscle fibres, and within this again some rather scattered longitudinal fibres; there is no endothelium. In their micro-structure the muscular fibres resemble those of nematodes.

Except for the absence of the longitudinal fibres the skin of the proboscis resembles that of the body, but the fluid-containing tubules of the proboscis are shut off from those of the body. The canals of the proboscis open into a circular vessel which runs round its base. From the circular canal two sac-like projections called the lemnisci run into the cavity of the body, alongside the proboscis cavity. Each consists of a prolongation of the syncytial material of the proboscis skin, penetrated by canals and sheathed with a muscular coat. They seem to act as reservoirs into which the fluid which is used to keep the proboscis "erect" can withdraw when it is retracted, and from which the fluid can be driven out when it is wished to expand the proboscis.

Nervous system
The central ganglion of the nervous system lies behind the proboscis sheath or septum. It innervates the proboscis and projects two stout trunks posteriorly which supply the body. Each of these trunks is surrounded by muscles, and this nerve-muscle complex is called a retinaculum. In the male at least there is also a genital ganglion. Some scattered papillae may possibly be sense-organs.

Life cycles
Acanthocephalans have complex life cycles, involving a number of hosts, for both developmental and resting stages. Complete life cycles have been worked out for only 25 species.

Reproduction
The Acanthocephala are dioecious (an individual organism is either male or female). There is a structure called the genital ligament which runs from the posterior end of the proboscis sheath to the posterior end of the body. In the male, two testes lie on either side of this. Each opens in a vas deferens which bears three diverticula or vesiculae seminales. The male also possesses three pairs of cement glands, found behind the testes, which pour their secretions through a duct into the vasa deferentia. These unite and end in a penis which opens posteriorly.

In the female, the ovaries are found, like the testes, as rounded bodies along the ligament. From the ovaries, masses of ova dehisce into the body cavity, floating in its fluids for fertilization by male's sperm. After fertilization, each egg contains a developing embryo. (These embryos hatch into first stage larva.) The fertilized eggs are brought into the uterus by actions of the uterine bell, a funnel like opening continuous with the uterus. At the junction of the bell and the uterus there is a second, smaller opening situated dorsally. The bell "swallows" the matured eggs and passes them on into the uterus. (Immature embryos are passed back into the body cavity through the dorsal opening.) From the uterus, mature eggs leave the female's body via her oviduct, pass into the host's alimentary canal and are expelled from the host's body within feces.

Release
Having been expelled by the female, the acanthocephalan egg is released along with the feces of the host. For development to occur, the egg, containing the acanthor, needs to be ingested by an arthropod, usually a crustacean (there is one known life cycle which uses a mollusc as a first intermediate host). Inside the intermediate host, the acanthor is released from the egg and develops into an acanthella. It then penetrates the gut wall, moves into the body cavity, encysts, and begins transformation into the infective cystacanth stage. This form has all the organs of the adult save the reproductive ones.

The parasite is released when the first intermediate host is ingested. This can be by a suitable final host, in which case the cystacanth develops into a mature adult, or by a paratenic host, in which the parasite again forms a cyst. When consumed by a suitable final host, the cycstacant excysts, everts its proboscis and pierces the gut wall. It then feeds, grows and develops its sexual organs. Adult worms then mate. The male uses the excretions of its cement glands to plug the vagina of the female, preventing subsequent matings from occurring. Embryos develop inside the female, and the life cycle repeats.

Host control
Thorny-headed worms begin their life cycle inside invertebrates that reside in marine or freshwater systems. Gammarus lacustris, a small crustacean that inhabits ponds and rivers, is one invertebrate that the thorny-headed worm may occupy. In recent years the occurrence of infections from these parasites have been increasing in Asian aquaculture practices. This crustacean is preyed on by ducks and hides by avoiding light and staying away from the surface. However, when infected by a thorny-headed worm it becomes attracted toward light and swims to the surface. Gammarus lacustris will even go so far as to find a rock or a plant on the surface, clamp its mouth down, and latch on, making it easy prey for the duck. The duck is the definitive host for the acanthocephalan parasite. In order to be transmitted to the duck, the parasite's intermediate host (the gammarid) must be eaten by the duck. This modification of gammarid behavior by the acanthocephalan is thought to increase the rate of transmission of the parasite to its next host by increasing the susceptibility of the gammarid to predation.

It is thought that when Gammarus lacustris is infected with a thorny-headed worm, the parasite causes serotonin to be massively expressed. Serotonin is a neurotransmitter involved in emotions and mood. Researchers have found that during mating Gammarus lacustris expresses high levels of serotonin. Also during mating, the male Gammarus lacustris clamps down on the female and holds on for days. Researchers have additionally found that blocking serotonin releases clamping. Another experiment found that serotonin also reduces the photophobic behavior in Gammarus lacustris. Thus, it is thought that the thorny-headed worm physiologically changes the behavior of the Gammarus lacustris in order to enter the bird, its final host.

Examples of this behaviour include the Polymorphus spp. which are parasites of seabirds, particularly the eider duck (Somateria mollissima). Heavy infections of up to 750 parasites per bird are common, causing ulceration to the gut, disease and seasonal mortality. Recent research has suggested that there is no evidence of pathogenicity of Polymorphus spp. to intermediate crab hosts. The cystacanth stage is long lived and probably remains infective throughout the life of the crab.

The life cycle of Polymorphus spp. normally occurs between sea ducks (e.g. eiders and scoters) and small crabs. Infections found in commercial-sized lobsters in Canada were probably acquired from crabs that form an important dietary item of lobsters. Cystacanths occurring in lobsters can cause economic loss to fishermen. There are no known methods of prevention or control.

Human infections
In humans, it causes the disease acanthocephaliasis. The earliest known infection was found in a prehistoric man in Utah. This infection was dated to 1869 ± 160 BC. The species involved was thought to be Moniliformis clarki which is still common in the area. The first report of an isolate in historic times was by Lambl in 1859 when he isolated Macracanthorhynchus hirudinaceus from a child in Prague. Lindemann in 1865 reported that this organism was commonly isolated in Russia. The reason for this was discovered by Schneider in 1871 when he found that an intermediate host, the scarabaeid beetle grub, was commonly eaten raw. The first report of clinical symptoms was by Calandruccio who in 1888 while in Italy infected himself by ingesting larvae. He reported gastrointestinal disturbances and shed eggs in two weeks. Subsequent natural infections have since been reported. Eight species have been isolated from humans to date. Moniliformis moniliformis is the most common isolate. Other isolates include Acanthocephalus bufonis and Corynosoma strumosum.

title: Acanthocephala


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Loricifera

Loricifera (from Latin, lorica, corselet (armour) + ferre, to bear) is a phylum of very small to microscopic marine cycloneuralian sediment-dwelling animals with 43 described species. and approximately 100 more that have been collected and not yet described. Their sizes range from 100 μm to ca.1 mm.

They are characterised by a protective outer case called a lorica and their habitat is in the spaces between marine gravel to which they attach themselves. The phylum was discovered in 1983 by R.M. Kristensen, near Roscoff, France. They are among the most recently discovered groups of animals. They attach themselves quite firmly to the substrate, and hence remained undiscovered for so long. The first specimen was collected in the 1970s, and described in 1983. They are found at all depths, in different sediment types, and in all latitudes.

Morphology
The animals have a head, mouth, and digestive system, as well as the lorica. The head (which contains the mouth and the brain), a trunk region surrounded by six plates that make up the 'lorica' or corselet and – in between these two – the neck region. Loricifera have a well developed brain and each scalid is individually connected to the brain by nerves. The armor-like lorica consists of a protective external shell or case of encircling plicae. There is no circulatory system and no endocrine system. Many of the larvae are acoelomate, with some adults being pseudocoelomate, and some remaining acoelomate. Development is generally direct, though there are so-called Higgins larvae, which differ from adults in several respects. As adults, the animals are gonochoric. Very complex and plastic life cycles of pliciloricids include also paedogenetic stages with different forms of parthenogenetic reproduction. Most Loricifera are dioecious, meaning there are males and females. However, there are a few species known to be hermaphroditic, which means they contain both male and female reproductive organs. Fossils have been dated to the late Cambrian.

Taxonomic affinity
Morphological studies have traditionally placed the phylum in the Vinctiplicata with the Priapulida; this plus the Kinorhyncha constitutes the taxon Scalidophora. The three phyla share four characters in common – chitinous cuticle, rings of scalids on the introvert, flosculi, and two rings of introvert retracts. However, despite a 2015 study showing the phylum's closest relatives being the Panarthropoda, a 2022 study again showed that it belonged to the Scalidophora and told that further, more comprehensive genetic tests will be required to find its actual position in Ecdysozoa.

Evolutionary history
The loriciferans are believed to be miniaturized descendants of a larger organism, perhaps resembling the Cambrian fossil Sirilorica. However, the fossil record of the microscopic non-mineralized group is (perhaps unsurprisingly) scarce, so it is difficult to trace out the evolutionary history of the phylum in any detail.

The 2017 discovery of the Cambrian Eolorica deadwoodensis may shed some light on the group's history.

In anoxic environments
Three species of Loricifera have been found in the oxygen-free sediments at the bottom of the L'Atalante basin in Mediterranean Sea, more than 3,000 meters down, the first multicellular organisms known to spend their entire lives in an anoxic environment. Initially, it was thought that they are able to do this because their mitochondria act like hydrogenosomes, allowing them to respire anaerobically. However, by 2021, questions arose as to whether or not they have mitochondria.

The newly reported animals complete their life cycle in the total absence of light and oxygen, and they are less than a millimetre in size. They were collected from a deep basin at the bottom of the Mediterranean Sea, where they inhabit a nearly salt-saturated brine that, because of its density (> 1.2 g/cm3), does not mix with the waters above. As a consequence, this environment is completely anoxic and, due to the activity of sulfate reducers, contains sulphide at a concentration of 2.9 mM. Despite such harsh conditions, this anoxic and sulphidic environment is teeming with microbial life, both chemosynthetic prokaryotes that are primary producers, and a broad diversity of eukaryotic heterotrophs at the next trophic level.

title: Loricifera


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Ralph Ellison

Ralph Ellison (March 1, 1913 – April 16, 1994) was an American writer, literary critic, and scholar best known for his novel Invisible Man, which won the National Book Award in 1953.

Ellison wrote Shadow and Act (1964), a collection of political, social, and critical essays, and Going to the Territory (1986). The New York Times dubbed him "among the gods of America's literary Parnassus".

A posthumous novel, Juneteenth, was published after being assembled from voluminous notes Ellison left upon his death.

Early life
Ralph Waldo Ellison, named after Ralph Waldo Emerson, was born in Oklahoma City, Oklahoma, to Lewis Alfred Ellison and Ida Millsap, on March 1, 1913. He was the second of three sons; firstborn Alfred died in infancy, and younger brother Herbert Maurice (or Millsap) was born in 1916. Lewis Alfred Ellison, a small-business owner and a construction foreman, died in 1916, after work-related injury and a failed operation. The elder Ellison loved literature, and doted on his children. Ralph later discovered, as an adult, that his father had hoped he would grow up to be a poet.

In 1921, Ellison's mother and her children moved to Gary, Indiana, where she had a brother. According to Ellison, his mother felt that "my brother and I would have a better chance of reaching manhood if we grew up in the north." When she did not find a job and her brother lost his, the family returned to Oklahoma, where Ellison worked as a busboy, a shoeshine boy, hotel waiter, and a dentist's assistant. From the father of a neighborhood friend, he received free lessons for playing trumpet and alto saxophone, and would go on to become the school bandmaster.

Ida remarried three times after Lewis died. However, the family life was precarious, and Ralph worked various jobs during his youth and teens to assist with family support. While attending Douglass High School, he also found time to play on the school's football team. He graduated from high school in 1931. He worked for a year, and found the money to make a down payment on a trumpet, using it to play with local musicians, and to take further music lessons. At Douglass, he was influenced by principal Inman E. Page and his daughter, music teacher Zelia N. Breaux.

At Tuskegee Institute
Ellison applied twice for admission to Tuskegee Institute, the prestigious all-black university in Alabama founded by Booker T. Washington. He was finally admitted in 1933 for lack of a trumpet player in its orchestra. Ellison hopped freight trains to get to Alabama, and was soon to find out that the institution was no less class-conscious than white institutions generally were.

Ellison's outsider position at Tuskegee "sharpened his satirical lens," critic Hilton Als believes: "Standing apart from the university's air of sanctimonious Negritude enabled him to write about it." In passages of Invisible Man, "he looks back with scorn and despair on the snivelling ethos that ruled at Tuskegee."

Tuskegee's music department was perhaps the most renowned department at the school, headed by composer William L. Dawson. Ellison also was guided by the department's piano instructor, Hazel Harrison. While he studied music primarily in his classes, he spent his free time in the library with modernist classics. He cited reading T. S. Eliot's The Waste Land as a major awakening moment. In 1934, he began to work as a desk clerk at the university library, where he read James Joyce and Gertrude Stein. Librarian Walter Bowie Williams enthusiastically let Ellison share in his knowledge.

A major influence upon Ellison was English teacher Morteza Drexel Sprague, to whom Ellison later dedicated his essay collection Shadow and Act. He opened Ellison's eyes to "the possibilities of literature as a living art" and to "the glamour he would always associate with the literary life." Through Sprague, Ellison became familiar with Fyodor Dostoevsky's Crime and Punishment and Thomas Hardy's Jude the Obscure, identifying with the "brilliant, tortured anti-heroes" of those works.

As a child, Ellison evidenced what would become a lifelong interest in audio technology, starting by taking apart and rebuilding radios, and later moving on to constructing and customizing elaborate hi-fi stereo systems as an adult. He discussed this passion in a December 1955 essay, "Living With Music", in High Fidelity magazine. Ellison scholar John S. Wright contends that this deftness with the ins-and-outs of electronic devices went on to inform Ellison's approach to writing and the novel form. Ellison remained at Tuskegee until 1936, and decided to leave before completing the requirements for a degree.

In New York
Desiring to study sculpture, he moved to New York City on July 5, 1936, and found lodging at a YMCA on 135th Street in Harlem, then "the culture capital of black America". He met Langston Hughes, "Harlem's unofficial diplomat" of the Depression era, and one—as one of the country's celebrity black authors—who could live from his writing. Hughes introduced him to the black literary establishment with Communist sympathies.

He met several artists who would influence his later life, including the artist Romare Bearden and the author Richard Wright (with whom he would have a long and complicated relationship). After Ellison wrote a book review for Wright, Wright encouraged him to write fiction as a career. His first published story was "Hymie's Bull", inspired by Ellison's 1933 hoboing on a train with his uncle to get to Tuskegee. From 1937 to 1944, Ellison had over 20 book reviews, as well as short stories and articles, published in magazines such as New Challenge and The New Masses.

Wright was then openly associated with the Communist Party, and Ellison was publishing and editing for communist publications, although his "affiliation was quieter", according to historian Carol Polsgrove in Divided Minds. Both Wright and Ellison lost their faith in the Communist Party during World War II, when they felt the party had betrayed African Americans and replaced Marxist class politics with social reformism. In a letter to Wright, dated August 18, 1945, Ellison poured out his anger with party leaders: "If they want to play ball with the bourgeoisie they needn't think they can get away with it. ... Maybe we can't smash the atom, but we can, with a few well chosen, well written words, smash all that crummy filth to hell." In the wake of this disillusion, Ellison began writing Invisible Man, a novel that was, in part, his response to the party's betrayal.

In 1938, Ellison met Rose Araminta Poindexter, a woman two years his senior. Rose Araminta Poindexter was an actress, starring in films such as The Upright Sinner (1931). Poindexter and Ellison were married in late 1938. Rose was a stage actress, and continued her career after their marriage. In biographer Arnold Rampersad's assessment of Ellison's taste in women, he was searching for one "physically attractive and smart who would love, honor, and obey him—but not challenge his intellect." At first they lived at 312 West 122nd Street, Rose's apartment, but moved to 453 West 140th Street after her income shrank. In 1941 he briefly had an affair with Sanora Babb, which he confessed to his wife afterward, and in 1943 the marriage was over. The couple officially divorced in 1945. As of April 2023, Poindexter remains alive at 111 years old.

At the start of World War II, Ellison was classed 1A by the local Selective Service System, and thus eligible for the draft. However, he was not drafted. Toward the end of the war, he enlisted in the United States Merchant Marine. In 1946, he married Fanny McConnell, an accomplished person in her own right: a scholarship graduate of the University of Iowa who was a founder of the Negro People's Theater in Chicago and a writer for The Chicago Defender. While he wrote Invisible Man, she helped support Ellison financially by working for American Medical Center for Burma Frontiers (the charity supporting Gordon S. Seagrave's medical missionary work ). In 1946, Ellison composed and wrote the lyrics for at least two songs, "Flirty" and "It Would Only Hurt Me If I Knew". From 1947 to 1951, he earned some money writing book reviews but spent most of his time working on Invisible Man. Fanny also helped type Ellison's longhand text and assisted him in editing the typescript as it progressed.

Published in 1952, Invisible Man explores the theme of a person's search for their identity and place in society, as seen from the perspective of the first-person narrator, an unnamed African American man, first in the Deep South and then in the New York City of the 1930s. In contrast to his contemporaries such as Richard Wright and James Baldwin, Ellison created characters that are dispassionate, educated, articulate, and self-aware. Through the protagonist, Ellison explores the contrasts between the Northern and Southern varieties of racism and their alienating effect. The narrator is "invisible" in a figurative sense, in that "people refuse to see" him, and also experiences a kind of dissociation. The novel also contains taboo issues such as incest and the controversial subject of communism.

Later years
In 1962, the futurist Herman Kahn recruited Ellison as a consultant to the Hudson Institute in an attempt to broaden its scope beyond defense-related research.

In 1964, Ellison published Shadow and Act, a collection of essays, and began to teach at Bard College, Rutgers University and Yale University, while continuing to work on his novel. The following year, a Book Week poll of 200 critics, authors, and editors was released that proclaimed Invisible Man the most important novel since World War II.

In 1967, Ellison experienced a major house fire at his summer home in Plainfield, Massachusetts, in which he claimed more than 300 pages of his second novel manuscript were lost. A perfectionist regarding the art of the novel, Ellison had said in accepting his National Book Award for Invisible Man that he felt he had made "an attempt at a major novel" and, despite the award, he was unsatisfied with the book. Ellison ultimately wrote more than 2,000 pages of this second novel but never finished it.

Ellison died on April 16, 1994, of pancreatic cancer and was interred in a crypt at Trinity Church Cemetery and Mausoleum in the Washington Heights neighborhood of Upper Manhattan.

Awards and recognition
Invisible Man won the 1953 US National Book Award for Fiction.

The award was his ticket into the American literary establishment. He eventually was admitted to the American Academy of Arts and Letters, received two President's Medals (from Lyndon Johnson and Ronald Reagan) and a State Medal from France. He was the first African-American admitted to the Century Association and was awarded an honorary Doctorate from Harvard University. Disillusioned by his experience with the Communist Party, he used his new fame to speak out for literature as a moral instrument. In 1955 he traveled to Europe, visiting and lecturing, settling for a time in Rome, where he wrote an essay that appeared in a 1957 Bantam anthology called A New Southern Harvest. Robert Penn Warren was in Rome during the same period, and the two writers became close friends. Later, Warren would interview Ellison about his thoughts on race, history, and the Civil Rights Movement for his book Who Speaks for the Negro? In 1958, Ellison returned to the United States to take a position teaching American and Russian literature at Bard College and to begin a second novel, Juneteenth. During the 1950s, he corresponded with his lifelong friend, the writer Albert Murray. In their letters they commented on the development of their careers, the Civil Rights Movement, and other common interests including jazz. Much of this material was published in the collection Trading Twelves (2000).

Writing essays about both the black experience and his love for jazz music, Ellison continued to receive major awards for his work. In 1969, he received the Presidential Medal of Freedom; the following year, he was made a Chevalier of the Ordre des Arts et des Lettres by France and became a permanent member of the faculty at New York University as the Albert Schweitzer Professor of Humanities, serving from 1970 to 1980.

In 1975, Ellison was elected to the American Academy of Arts and Letters, and his hometown of Oklahoma City honored him with the dedication of the Ralph Waldo Ellison Library. Continuing to teach, Ellison published mostly essays, and in 1984, he received the New York City College's Langston Hughes Medal. In 1985, he was awarded the National Medal of Arts. In 1986, his Going to the Territory was published; this is a collection of seventeen essays that included insight into southern novelist William Faulkner and Ellison's friend Richard Wright, as well as the music of Duke Ellington and the contributions of African Americans to America's national identity.

In 1992, Ellison was awarded a special achievement award from the Anisfield-Wolf Book Awards; his artistic achievements included work as a sculptor, musician, photographer, and college professor as well as his writing output. He taught at Bard College, Rutgers University, the University of Chicago, and New York University. Ellison was also a charter member of the Fellowship of Southern Writers.

Legacy and posthumous publications
After Ellison's death, more manuscripts were discovered in his home, resulting in the publication of Flying Home and Other Stories in 1996. In 1999, his second novel, Juneteenth, was published under the editorship of John F. Callahan, a professor at Lewis & Clark College and Ellison's literary executor. It was a 368-page condensation of more than 2,000 pages written by Ellison over a period of 40 years. All the manuscripts of this incomplete novel were published collectively on January 26, 2010, by Modern Library, under the title Three Days Before the Shooting...

On February 18, 2014, the USPS issued a 91¢ stamp honoring Ralph Ellison in its Literary Arts series.

A park on 150th Street and Riverside Drive in Harlem (near 730 Riverside Drive, Ellison's principal residence from the early 1950s until his death) was dedicated to Ellison on May 1, 2003. In the park stands a 15 by 8-foot bronze slab with a "cut-out man figure" inspired by his book Invisible Man.

Essay collections

 * Shadow and Act (Random House, 1964). ISBN 0679760008
 * Going to the Territory (Random House, 1986). ISBN 0394540506
 * The Collected Essays of Ralph Ellison (Modern Library, 1995). ISBN 0679601767
 * Living with Music: Ralph Ellison's Jazz Writings (Modern Library, 2002). ISBN 0375760237

Letters

 * The Selected Letters of Ralph Ellison. Eds. John F Callahan and Marc C. Conner (Random House, 2019).'' ISBN 978-0812998528
 * Trading Twelves: The Selected Letters of Ralph Ellison and Albert Murray (Modern Library, 2000). ISBN 0375503676

title: Ralph Ellison


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title: User:Mikedill


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Richard Wright (author)

Richard Nathaniel Wright (September 4, 1908 – November 28, 1960) was an American author of novels, short stories, poems, and non-fiction. Much of his literature concerns racial themes, especially related to the plight of African Americans during the late 19th to mid 20th centuries suffering discrimination and violence. His best known works include the novella collection Uncle Tom's Children (1938), the novel Native Son (1940), and the memoir Black Boy (1945). Literary critics believe his work helped change race relations in the United States in the mid-20th century.

Childhood in the South
Richard Nathaniel Wright was born on September 4, 1908, at Rucker's Plantation, between the train town of Roxie and the larger river city of Natchez, Mississippi. He was the son of Nathan Wright, a sharecropper, and Ella (Wilson), a schoolteacher. His parents were born free after the Civil War; both sets of his grandparents had been born into slavery and freed as a result of the war. Each of his grandfathers had taken part in the U.S. Civil War and gained freedom through service: his paternal grandfather, Nathan Wright, had served in the 28th United States Colored Troops; his maternal grandfather, Richard Wilson, escaped from slavery in the South to serve in the U.S. Navy as a Landsman in April 1865.

Richard's father left the family when Richard was six years old, and he did not see Richard for 25 years. In 1911 or 1912 Ella moved to Natchez, Mississippi, to be with her parents. While living in his grandparents' home, he accidentally set the house on fire. Wright's mother was so angry that she beat him until he was unconscious. In 1915, Ella put her sons in Settlement House, a Methodist orphanage, for a short time. He was enrolled at Howe Institute in Memphis from 1915 to 1916. In 1916, his mother moved with Richard and his younger brother to live with her sister Maggie (Wilson) and Maggie's husband Silas Hoskins (born 1882) in Elaine, Arkansas. This part of Arkansas was in the Mississippi Delta where former cotton plantations had been. The Wrights were forced to flee after Silas Hoskins "disappeared," reportedly killed by a white man who coveted his successful saloon business. After his mother became incapacitated by a stroke, Richard was separated from his younger brother and lived briefly with his uncle Clark Wilson and aunt Jodie in Greenwood, Mississippi. At the age of 12, he had not yet had a single complete year of schooling. Soon Richard with his younger brother and mother returned to the home of his maternal grandmother, which was now in the state capital, Jackson, Mississippi, where he lived from early 1920 until late 1925. His grandparents, still angry at him for destroying their house, repeatedly beat Wright and his brother. But while he lived there, he was finally able to attend school regularly. He attended the local Seventh-day Adventist school from 1920 to 1921, with his aunt Addie as his teacher. After a year, at the age of 13 he entered the Jim Hill public school in 1921, where he was promoted to sixth grade after only two weeks. In his grandparents' Seventh-day Adventist home, Richard was miserable, largely because his controlling aunt and grandmother tried to force him to pray so he might build a relationship with God. Wright later threatened to move out of his grandmother's home when she would not allow him to work on the Adventist Sabbath, Saturday. His aunt's and grandparents' overbearing attempts to control him caused him to carry over hostility towards Biblical and Christian teachings to solve life's problems. This theme would weave through his writings throughout his life.

At the age of 15, while in eighth grade, Wright published his first story, "The Voodoo of Hell's Half-Acre," in the local Black newspaper Southern Register. No copies survive. In Chapter 7 of Black Boy, he described the story as about a villain who sought a widow's home.

In 1923, after excelling in grade school and junior high, Wright earned the position of class valedictorian of Smith Robertson Junior High School from which he graduated in May 1925. He was assigned to write a speech to be delivered at graduation in a public auditorium. Before graduation day, he was called to the principal's office, where the principal gave him a prepared speech to present in place of his own. Richard challenged the principal, saying "the people are coming to hear the students, and I won't make a speech that you've written." The principal threatened him, suggesting that Richard might not be allowed to graduate if he persisted, despite his having passed all the examinations. He also tried to entice Richard with an opportunity to become a teacher. Determined not to be called an Uncle Tom, Richard refused to deliver the principal's address, written to avoid offending the white school district officials. He was able to convince everyone to allow him to read the words he had written himself.

In September that year, Wright registered for mathematics, English, and history courses at the new Lanier High School, constructed for black students in Jackson—the state's schools were segregated under its Jim Crow laws—but he had to stop attending classes after a few weeks of irregular attendance because he needed to earn money to support his family.

In November 1925 at the age of 17, Wright moved on his own to Memphis, Tennessee. There he fed his appetite for reading. His hunger for books was so great that Wright devised a successful ploy to borrow books from the segregated white library. Using a library card lent by a white coworker, which he presented with forged notes that claimed he was picking up books for the white man, Wright was able to obtain and read books forbidden to black people in the Jim Crow South. This stratagem also allowed him access to publications such as Harper's, the Atlantic Monthly, and The American Mercury.

He planned to have his mother come and live with him once he could support her, and in 1926, his mother and younger brother did rejoin him. Shortly thereafter, Richard resolved to leave the Jim Crow South and go to Chicago. His family joined the Great Migration, when tens of thousands of blacks left the South to seek opportunities in the more economically prosperous northern and mid-western industrial cities.

Wright's childhood in Mississippi, Tennessee, and Arkansas shaped his lasting impressions of American racism.

Coming of age in Chicago
Wright and his family moved to Chicago in 1927, where he secured employment as a United States postal clerk. He used his time in between shifts to study other writers including H.L. Mencken, whose vision of the American South as a version of Hell made an impression. When he lost his job there during the Great Depression, Wright was forced to go on relief in 1931. In 1932, he began attending meetings of the John Reed Club, a Marxist literary organization. Wright established relationships and networked with party members. Wright formally joined the Communist Party and the John Reed Club in late 1933 at the urging of his friend Abraham Aaron. As a revolutionary poet, he wrote proletarian poems ("We of the Red Leaves of Red Books", for example), for New Masses and other communist-leaning periodicals. A power struggle within the Chicago chapter of the John Reed Club had led to the dissolution of the club's leadership; Wright was told he had the support of the club's party members if he was willing to join the party.

In 1933, Wright founded the South Side Writers Group, whose members included Arna Bontemps and Margaret Walker. Through the group and his membership in the John Reed Club, Wright founded and edited Left Front, a literary magazine. Wright began publishing his poetry ("A Red Love Note" and "Rest for the Weary" for example) there in 1934. There is dispute about the demise in 1935 of Left Front Magazine as Wright blamed the Communist Party despite his protests. It is however likely due to the proposal at the 1934 Midwest Writers Congress that the John Reed Club be replaced by a Communist Party-sanctioned First American Party Congress. Throughout this period, Wright continued to contribute to New Masses magazine, revealing the path his writings would ultimately take.

By 1935, Wright had completed the manuscript of his first novel, Cesspool, which was rejected by eight publishers and published posthumously as Lawd Today (1963). This first work featured autobiographical anecdotes about working at a post office in Chicago during the Great Depression.

In January 1936 his story "Big Boy Leaves Home" was accepted for publication in the anthology New Caravan and the anthology Uncle Tom's Children, focusing on black life in the rural American South.

In February of that year, he began working with the National Negro Congress (NNC), speaking at the Chicago convention on "The Role of the Negro Artist and Writer in the Changing Social Order". His ultimate goal (looking at other labor unions as inspiration) was the development of NNC-sponsored publications, exhibits, and conferences alongside the Federal Writers' Project to get work for black artists.

In 1937, he became the Harlem editor of the Daily Worker. This assignment compiled quotes from interviews preceded by an introductory paragraph, thus allowing him time for other pursuits like the publication of Uncle Tom's Children a year later.

Pleased by his positive relations with white Communists in Chicago, Wright was later humiliated in New York City by some white party members who rescinded an offer to find housing for him when they learned his race. Some black Communists denounced Wright as a "bourgeois intellectual." Wright was essentially autodidactic. He had been forced to end his public education to support his mother and brother after completing junior high school.

Throughout the Soviet pact with Nazi Germany in 1940, Wright continued to focus his attention on racism in the United States. He would ultimately break from the Communist Party when they broke from a tradition against segregation and racism and joined Stalinists supporting the US entering World War II in 1941.

Wright insisted that young communist writers be given space to cultivate their talents. Wright later described this episode through his fictional character Buddy Nealson, an African-American communist, in his essay "I tried to be a Communist," published in the Atlantic Monthly in 1944. This text was an excerpt of his autobiography scheduled to be published as American Hunger but was removed from the actual publication of Black Boy upon request by the Book of the Month Club. Indeed, his relations with the party turned violent; Wright was threatened at knifepoint by fellow-traveler co-workers, denounced as a Trotskyite in the street by strikers, and physically assaulted by former comrades when he tried to join them during the 1936 Labour Day march.

Career
In Chicago in 1932, Wright began writing with the Federal Writer's Project and became a member of the American Communist Party. In 1937, he relocated to New York and became the Bureau Chief of the communist publication, the Daily Worker. He would write over 200 articles for the publication from 1937 to 1938. This allowed him to cover stories and issues that interested him, revealing depression-era America into light with well-written prose.

He worked on the Federal Writers' Project guidebook to the city, New York Panorama (1938), and wrote the book's essay on Harlem. Through the summer and fall he wrote more than 200 articles for the Daily Worker and helped edit a short-lived literary magazine, New Challenge. The year was also a landmark for Wright because he met and developed a friendship with writer Ralph Ellison that would last for years. He was awarded the Story magazine first prize of $500 for his short story "Fire and Cloud".

After receiving the Story prize in early 1938, Wright shelved his manuscript of Lawd Today and dismissed his literary agent, John Troustine. He hired Paul Reynolds, the well-known agent of poet Paul Laurence Dunbar, to represent him. Meanwhile, the Story Press offered the publisher Harper all of Wright's prize-entry stories for a book, and Harper agreed to publish the collection.

Wright gained national attention for the collection of four short stories entitled Uncle Tom's Children (1938). He based some stories on lynching in the Deep South. The publication and favorable reception of Uncle Tom's Children improved Wright's status with the Communist party and enabled him to establish a reasonable degree of financial stability. He was appointed to the editorial board of New Masses. Granville Hicks, a prominent literary critic and Communist sympathizer, introduced him at leftist teas in Boston. By May 6, 1938, excellent sales had provided Wright with enough money to move to Harlem, where he began writing the novel Native Son, which was published in 1940.

Based on his collected short stories, Wright applied for and was awarded a Guggenheim Fellowship, which gave him a stipend allowing him to complete Native Son. During this period, he rented a room in the home of friends Herbert and Jane Newton, an interracial couple and prominent Communists whom Wright had known in Chicago. They had moved to New York and lived at 109 Lefferts Place in Brooklyn in the Fort Greene neighborhood.

After publication, Native Son was selected by the Book of the Month Club as its first book by an African-American author. It was a daring choice. The lead character, Bigger Thomas, is bound by the limitations that society places on African Americans. Unlike most in this situation, he gains his own agency and self-knowledge only by committing heinous acts. Wright's characterization of Bigger led to him being criticized for his concentration on violence in his works. In the case of Native Son, people complained that he portrayed a black man in ways that seemed to confirm whites' worst fears. The period following publication of Native Son was a busy time for Wright. In July 1940 he went to Chicago to do research for a folk history of blacks to accompany photographs selected by Edwin Rosskam. While in Chicago he visited the American Negro Exposition with Langston Hughes, Arna Bontemps and Claude McKay.

Wright traveled to Chapel Hill, North Carolina, to collaborate with playwright Paul Green on a dramatic adaptation of Native Son. In January 1941 Wright received the prestigious Spingarn Medal of the NAACP for noteworthy achievement. His play Native Son opened on Broadway in March 1941, with Orson Welles as director, to generally favorable reviews. Wright also wrote the text to accompany a volume of photographs chosen by Rosskam, which were almost completely drawn from the files of the Farm Security Administration. The FSA had employed top photographers to travel around the country and capture images of Americans. Their collaboration, 12 Million Black Voices: A Folk History of the Negro in the United States, was published in October 1941 to wide critical acclaim.

Wright's memoir Black Boy (1945) describes his early life from Roxie up until his move to Chicago at age 19. It includes his clashes with his Seventh-day Adventist family, his troubles with white employers, and social isolation. It also describes his intellectual journey through these struggles. American Hunger, which was published posthumously in 1977, was originally intended by Wright as the second volume of Black Boy. The Library of America edition of 1991 finally restored the book to its original two-volume form.

American Hunger details Wright's participation in the John Reed Clubs and the Communist Party, which he left in 1942. The book implies he left earlier, but he did not announce his withdrawal until 1944. In the book's restored form, Wright used the diptych structure to compare the certainties and intolerance of organized communism, which condemned "bourgeois" books and certain members, with similar restrictive qualities of fundamentalist organized religion. Wright disapproved of Joseph Stalin's Great Purge in the Soviet Union.

France

Following a stay of a few months in Québec, Canada, including a lengthy stay in the village of Sainte-Pétronille on the Île d'Orléans, Wright moved to Paris in 1946. He became a permanent American expatriate.

In Paris, Wright became friends with French writers Jean-Paul Sartre and Albert Camus, whom he had met while still in New York, and he and his wife became particularly good friends with Simone de Beauvoir, who stayed with them in 1947. However, as Michel Fabre argues, Wright's existentialist leanings were more influenced by Soren Kierkegaard, Edmund Husserl, and especially Martin Heidegger. In following Fabre's argument, with respect to Wright's existentialist proclivities during the period of 1946 to 1951, Hue Woodson suggests that Wright's exposure to Husserl and Heidegger "directly came as an intended consequence of the inadequacies of Sartre's synthesis of existentialism and Marxism for Wright." His Existentialist phase was expressed in his second novel, The Outsider (1953), which described an African-American character's involvement with the Communist Party in New York. He also became friends with fellow expatriate writers Chester Himes and James Baldwin. His relationship with the latter ended in acrimony after Baldwin published his essay "Everybody's Protest Novel" (collected in Notes of a Native Son), in which he criticized Wright's portrayal of Bigger Thomas as stereotypical. In 1954 Wright published Savage Holiday.

After becoming a French citizen in 1947, Wright continued to travel through Europe, Asia, and Africa. He drew material from these trips for numerous nonfiction works. In 1949, Wright contributed to the anti-communist anthology The God That Failed; his essay had been published in the Atlantic Monthly three years earlier and was derived from the unpublished portion of Black Boy. He was invited to join the Congress for Cultural Freedom, which he rejected, correctly suspecting that it had connections with the CIA. Fearful of links between African Americans and communists, the FBI had Wright under surveillance starting in 1943. With the heightened communist fears of the 1950s, Wright was blacklisted by Hollywood movie studio executives. But in 1950, he starred as the teenager Bigger Thomas (Wright was 42) in an Argentinian film version of Native Son.

In mid-1953, Wright traveled to the Gold Coast, where Kwame Nkrumah was leading the country to independence from British rule, to be established as Ghana. Before Wright returned to Paris, he gave a confidential report to the United States consulate in Accra on what he had learned about Nkrumah and his political party. After Wright returned to Paris, he met twice with an officer from the U.S. State Department. The officer's report includes what Wright had learned from Nkrumah's adviser George Padmore about Nkrumah's plans for the Gold Coast after independence. Padmore, a Trinidadian living in London, believed Wright to be a good friend. His many letters in the Wright papers at Yale's Beinecke Library attest to this, and the two men continued their correspondence. Wright's book on his African journey, Black Power, was published in 1954; its London publisher was Dennis Dobson, who also published Padmore's work.

Whatever political motivations Wright had for reporting to American officials, he was also an American who wanted to stay abroad and needed their approval to have his passport renewed. According to Wright biographer Addison Gayle, a few months later Wright talked to officials at the American embassy in Paris about people he had met in the Communist Party; at the time these individuals were being prosecuted in the US under the Smith Act.

Historian Carol Polsgrove explored why Wright appeared to have little to say about the increasing activism of the civil rights movement during the 1950s in the United States. She found that Wright was under what his friend Chester Himes called "extraordinary pressure" to avoid writing about the US. As Ebony magazine delayed publishing his essay, "I Choose Exile," Wright finally suggested publishing it in a white periodical. He believed that "a white periodical would be less vulnerable to accusations of disloyalty." He thought the Atlantic Monthly was interested, but in the end, the piece went unpublished.

In 1955, Wright visited Indonesia for the Bandung Conference. He recorded his observations on the conference as well as on Indonesian cultural conditions in The Color Curtain: A Report on the Bandung Conference. Wright was enthusiastic about the possibilities posed by this meeting of newly independent, former colonial nations. He gave at least two lectures to Indonesian cultural groups, including PEN Club Indonesia, and he interviewed Indonesian artists and intellectuals in preparation to write The Color Curtain. Several Indonesian artists and intellectuals whom Wright met, later commented on how he had depicted Indonesian cultural conditions in his travel writing.

Other works by Wright included White Man, Listen! (1957) and a novel The Long Dream (1958), which was adapted as a play and produced in New York in 1960 by Ketti Frings. It explores the relationship between a man named Fish and his father. A collection of short stories, Eight Men, was published posthumously in 1961, shortly after Wright's death. These works dealt primarily with the poverty, anger, and protests of northern and southern urban black Americans.

His agent, Paul Reynolds, sent strongly negative criticism of Wright's 400-page Island of Hallucinations manuscript in February 1959. Despite that, in March Wright outlined a novel in which his character Fish was to be liberated from racial conditioning and become dominating. By May 1959, Wright wanted to leave Paris and live in London. He felt French politics had become increasingly submissive to United States pressure. The peaceful Parisian atmosphere he had enjoyed had been shattered by quarrels and attacks instigated by enemies of the expatriate black writers.

On June 26, 1959, after a party marking the French publication of White Man, Listen!, Wright became ill. He suffered a virulent attack of amoebic dysentery, probably contracted during his 1953 stay on the Gold Coast. By November 1959 his wife had found a London apartment, but Wright's illness and "four hassles in twelve days" with British immigration officials ended his desire to live in England.

On February 19, 1960, Wright learned from his agent Reynolds that the New York premiere of the stage adaptation of The Long Dream received such bad reviews that the adapter, Ketti Frings, had decided to cancel further performances. Meanwhile, Wright was running into added problems trying to get The Long Dream published in France. These setbacks prevented his finishing revisions of Island of Hallucinations, for which he was trying to get a publication commitment from Doubleday and Company.

In June 1960, Wright recorded a series of discussions for French radio, dealing primarily with his books and literary career. He also addressed the racial situation in the United States and the world, and specifically denounced American policy in Africa. In late September, to cover extra expenses for his daughter Julia's move from London to Paris to attend the Sorbonne, Wright wrote blurbs for record jackets for Nicole Barclay, director of the largest record company in Paris.

In spite of his financial straits, Wright refused to compromise his principles. He declined to participate in a series of programs for Canadian radio because he suspected American control. For the same reason, he rejected an invitation from the Congress for Cultural Freedom to go to India to speak at a conference in memory of Leo Tolstoy. Still interested in literature, Wright helped Kyle Onstott get his novel Mandingo (1957) published in France.

Wright's last display of explosive energy occurred on November 8, 1960, in his polemical lecture, "The Situation of the Black Artist and Intellectual in the United States," delivered to students and members of the American Church in Paris. He argued that American society reduced the most militant members of the black community to slaves whenever they wanted to question the racial status quo. He offered as proof the subversive attacks of the Communists against Native Son and the quarrels which James Baldwin and other authors sought with him. On November 26, 1960, Wright talked enthusiastically with Langston Hughes about his work Daddy Goodness and gave him the manuscript. Wright died of a heart attack in Paris on November 28, 1960, at the age of 52. He was interred in Père Lachaise Cemetery. Wright's daughter Julia has claimed that her father was murdered.

A number of Wright's works have been published posthumously. In addition, some of Wright's more shocking passages dealing with race, sex, and politics were cut or omitted before original publication of works during his lifetime. In 1991, unexpurgated versions of Native Son, Black Boy, and his other works were published. In addition, in 1994, his novella Rite of Passage was published for the first time.

In the last years of his life, Wright had become enamored of the Japanese poetic form haiku and wrote more than 4,000 such short poems. In 1998 a book was published (Haiku: This Other World) with 817 of his own favorite haiku. Many of these haiku have an uplifting quality even as they deal with coming to terms with loneliness, death, and the forces of nature.

A collection of Wright's travel writings was published by the University Press of Mississippi in 2001. At his death, Wright left an unfinished book, A Father's Law, dealing with a black policeman and the son he suspects of murder. His daughter Julia Wright published A Father's Law in January 2008. An omnibus edition containing Wright's political works was published under the title Three Books from Exile: Black Power; The Color Curtain; and White Man, Listen!

Personal life
In August 1939, with Ralph Ellison as best man, Wright married Dhimah Rose Meidman, a modern dance teacher of Russian Jewish ancestry. The marriage ended a year later.

On March 12, 1941, he married Ellen Poplar (née Poplowitz), a Communist organizer from Brooklyn. They had two daughters: Julia, born in 1942, and Rachel, born in 1949.

Ellen Wright, who died on April 6, 2004, aged 92, was the executor of Wright's estate. In this capacity, she unsuccessfully sued a biographer, the poet and writer Margaret Walker, in Wright v. Warner Books, Inc. She was a literary agent, and her clients included Simone de Beauvoir, Eldridge Cleaver, and Violette Leduc.

Awards and honors

 * The Spingarn Medal in 1941 from the NAACP
 * Guggenheim Fellowship in 1939
 * Story Magazine Award in 1938.
 * In April 2009, Wright was featured on a U.S. postage stamp. The 61-cent, two-ounce rate stamp is the 25th installment of the literary arts series, and features a portrait of Wright in front of snow-swept tenements on the South Side of Chicago, a scene that recalls the setting of Native Son.
 * In 2010, Wright was inducted into the Chicago Literary Hall of Fame.
 * In 2012, the Historic Districts Council and the New York City Landmarks Preservation Commission, in collaboration with the Fort Greene Association and writer/musician Carl Hancock Rux, erected a cultural medallion at 175 Carlton Avenue, Brooklyn, where Wright lived in 1938 and completed Native Son. The group unveiled the plaque at a public ceremony with guest speakers, including playwright Lynn Nottage and Brooklyn Borough President Marty Markowitz.

Legacy

Black Boy became an instant best-seller upon its publication in 1945. Wright's stories published during the 1950s disappointed some critics who said that his move to Europe had alienated him from African Americans and separated him from his emotional and psychological roots. Many of Wright's works failed to satisfy the rigid standards of New Criticism during a period when the works of younger black writers gained in popularity.

During the 1950s Wright grew more internationalist in outlook. While he accomplished much as an important public literary and political figure with a worldwide reputation, his creative work did decline.

While interest in Black Boy ebbed during the 1950s, this has remained one of his best selling books. Since the late 20th century, critics have had a resurgence of interest in it. Black Boy remains a vital work of historical, sociological, and literary significance whose seminal portrayal of one black man's search for self-actualization in a racist society strongly influenced the works of African-American writers who followed, such as James Baldwin and Ralph Ellison. John A. Williams included a fictionalized version of Wright's life and death in his 1967 novel The Man Who Cried I Am.

It is generally agreed that the influence of Wright's Native Son is not a matter of literary style or technique. Rather, this book affected ideas and attitudes, and Native Son has been a force in the social and intellectual history of the United States in the last half of the 20th century. "Wright was one of the people who made me conscious of the need to struggle," said writer Amiri Baraka.

During the 1970s and 1980s, scholars published critical essays about Wright in prestigious journals. Richard Wright conferences were held on university campuses from Mississippi to New Jersey. A new film version of Native Son, with a screenplay by Richard Wesley, was released in December 1986. Certain Wright novels became required reading in a number of American high schools, universities and colleges.

Recent critics have called for a reassessment of Wright's later work in view of his philosophical project. Notably, Paul Gilroy has argued that "the depth of his philosophical interests has been either overlooked or misconceived by the almost exclusively literary inquiries that have dominated analysis of his writing."

Wright was featured in a 90-minute documentary about the WPA Writers' Project entitled Soul of a People: Writing America's Story (2009). His life and work during the 1930s is highlighted in the companion book, Soul of a People: The WPA Writers' Project Uncovers Depression America.

Collections

 * Uncle Tom's Children (New York: Harper, 1938) (collection of novellas)
 * Eight Men (Cleveland and New York: World, 1961)
 * "The Man Who Was Almost a Man"
 * "The Man Who Lived Underground" (truncated version)
 * "Big Black Man"
 * "The Man Who Saw the Flood"
 * "Man of All Work"
 * "Man, God Ain't That..."
 * "The Man Who Killed a Shadow"
 * "The Man Who Went to Chicago"
 * Early Works (Arnold Rampersad, ed.) (Library of America, 1989),
 * Later Works (Arnold Rampersad, ed.) (Library of America, 1991).

Drama

 * Native Son: The Biography of a Young American with Paul Green (New York: Harper, 1941)

Novels

 * Native Son (New York: Harper, 1940)
 * The Outsider (New York: Harper, 1953)
 * Savage Holiday (New York: Avon, 1954)
 * The Long Dream (Garden City, New York: Doubleday, 1958)
 * Lawd Today (New York: Walker, 1963)
 * Rite of Passage (New York: HarperCollins, 1994) (novella)
 * A Father's Law (London: Harper Perennial, 2008) (unfinished novel)
 * The Man Who Lived Underground (Library of America, 2021) (extended novel, as originally )

Non-fiction

 * How "Bigger" Was Born; Notes of a Native Son (New York: Harper, 1940)
 * 12 Million Black Voices: A Folk History of the Negro in the United States (New York: Viking, 1941)
 * Black Boy (New York: Harper, 1945)
 * Black Power (New York: Harper, 1954)
 * The Color Curtain (Cleveland and New York: World, 1956)
 * Pagan Spain (New York: Harper, 1957)
 * Letters to Joe C. Brown (Kent State University Libraries, 1968)
 * American Hunger (New York: Harper & Row, 1977)
 * Conversations with Richard Wright (Univ. Press of Mississippi, 1993).
 * Black Power: Three Books from Exile: "Black Power"; "The Color Curtain"; and "White Man, Listen!" (Harper Perennial, 2008)

Essays

 * The Ethics of Living Jim Crow: An Autobiographical Sketch (1937)
 * Introduction to Black Metropolis: A Study of Negro Life in a Northern City (1945)
 * I Choose Exile (1951)
 * White Man, Listen! (Garden City, New York: Doubleday, 1957)
 * Blueprint for Negro Literature (New York City, New York) (1937)
 * The God That Failed (contributor) (1949)

 * Poetry
 * Haiku: This Other World (eds. Yoshinobu Hakutani and Robert L. Tener; Arcade, 1998, ISBN 0385720246)
 * re-issue (paperback): Haiku: The Last Poetry of Richard Wright (Arcade Publishing, 2012), ISBN 978-1-61145-349-2

Books

 * Fabre, Michel. The World of Richard Wright (Univ. Press of Mississippi, 1985).
 * Fabre, Michel. The unfinished quest of Richard Wright (U of Illinois Press, 1993).
 * Fishburn, Katherine. Richard Wright's Hero: The Faces of a Rebel-Victim (Scarecrow Press, 1977).
 * Rampersad, Arnold, ed. Richard Wright: A Collection of Critical Essays (1994)
 * Rowley, Hazel. Richard Wright: The life and times (U of Chicago Press, 2008).
 * Smith, Virginia Whatley, ed. Richard Wright Writing America at Home and from Abroad (Univ. Press of Mississippi, 2016).
 * Ward, Jerry W., and Robert J. Butler, eds. The Richard Wright Encyclopedia (ABC-CLIO, 2008).

Journal articles

 * Alsen, Eberhard. "'Toward The Living Sun': Richard Wright's Change Of Heart From 'The Outsider' To 'The Long Dream, CLA Journal 38.2 (1994): 211–227. online
 * Bone, Robert. "Richard Wright and the Chicago Renaissance", Callaloo 28 (1986): 446–468. online
 * Burgum, Edwin Berry. "The Promise of Democracy and the Fiction of Richard Wright", Science & Society, vol. 7, no. 4 (Fall 1943), pp. 338–352. In JSTOR.
 * Bradley, M. (2018). "Richard Wright, Bandung, and the Poetics of the Third World." Modern American History, 1(1), 147–150.
 * Cauley, Anne O. "A Definition of Freedom in the Fiction of Richard Wright", CLA Journal 19.3 (1976): 327–346. online
 * Cobb, Nina Kressner. "Richard Wright: exile and existentialism", Phylon 40.4 (1979): 362–374. online
 * Gines, Kathryn T. "'The Man Who Lived Underground': Jean-Paul Sartre And the Philosophical Legacy of Richard Wright", Sartre Studies International 17.2 (2011): 42–59.
 * Knapp, Shoshana Milgram. "Recontextualizing Richard Wright's The Outsider: Hugo, Dostoevsky, Max Eastman, and Ayn Rand", in Richard Wright in a Post-Racial Imaginary (2014), pp. 99–112.
 * Meyerson, Gregory. "Aunt Sue's Mistake: False Consciousness in Richard Wright's 'Bright and Morning Star, in Reconstruction: Studies in Culture: 2008 8#4 online
 * Veninga, Jennifer Elisa. "Richard Wright: Kierkegaard's Influence as Existentialist Outsider", in Kierkegaard's Influence on Social-Political Thought (Routledge, 2016), pp. 281–298.
 * Widmer, Kingsley, and Richard Wright. "The Existential Darkness: Richard Wright's 'The Outsider, Wisconsin Studies in Contemporary Literature 1.3 (1960): 13–21. online
 * Woodson, Hue. "Heidegger and The Outsider, Savage Holiday, and The Long Dream" in Critical Insights: Richard Wright. Ed. Kimberly Drake (Amenia, NY: Grey House, 2019).
 * Veninga, Jennifer Elisa. "Richard Wright: Kierkegaard's Influence as Existentialist Outsider", in Kierkegaard's Influence on Social-Political Thought (Routledge, 2016), pp. 281–298.
 * Widmer, Kingsley, and Richard Wright. "The Existential Darkness: Richard Wright's 'The Outsider, Wisconsin Studies in Contemporary Literature 1.3 (1960): 13–21. online
 * Woodson, Hue. "Heidegger and The Outsider, Savage Holiday, and The Long Dream" in Critical Insights: Richard Wright. Ed. Kimberly Drake (Amenia, NY: Grey House, 2019).

Archival materials

 * Richard Wright Papers. Yale Collection of American Literature, Beinecke Rare Book and Manuscript Library.
 * Richard Wright Collection (MUM00488) at the University of Mississippi.
 * Richard Wright Book Project materials in the papers of sociologist Horace R. Clayton Jr. at Chicago Public Library

title: Richard Wright (author)