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War elephant

A war elephant was an elephant that was trained and guided by humans for combat. The war elephant's main use was to charge the enemy, break their ranks, and instill terror and fear. Elephantry is a term for specific military units using elephant-mounted troops.

Description
War elephants played a critical role in several key battles in antiquity, especially in ancient India. While seeing limited and periodic use in Ancient China, they became a permanent fixture in armies of historical kingdoms in Southeast Asia. During classical antiquity they were also used in ancient Persia and in the Mediterranean world within armies of Macedon, Hellenistic Greek states, the Roman Republic and later Empire, and Ancient Carthage in North Africa. In some regions they maintained a firm presence on the battlefield throughout the Medieval era. However, their use declined with the spread of firearms and other gunpowder weaponry in early modern warfare. After this, war elephants became restricted to non-combat engineering and labour roles, as well as being used for minor ceremonial uses. They continued to be used in combat, however, in some parts of the world, such as in Burma, Thailand, and Vietnam, well into the 19th century.

Taming

An elephant trainer, rider, or keeper is called a mahout. Mahouts were responsible for capturing and handling elephants. To accomplish this, they utilize metal chains and a specialized hook called an ankus, or 'elephant goad'. According to Chanakya as recorded in the Arthashastra, first the mahout would have to get the elephant used to being led. The elephant would have learned how to raise its legs to help a rider climb on. Then the elephants were taught to run and maneuver around obstacles, and move in formation. These elephants would be fit to learn how to systematically trample and charge enemies.

The first elephant species to be tamed was the Asian elephant, for use in agriculture. Elephant taming – not full domestication, as they are still captured in the wild, rather than being bred in captivity – may have begun in any of three different places. The oldest evidence comes from the Indus Valley civilization, around roughly 2000 BC. Archaeological evidence for the presence of wild elephants in the Yellow River valley in Shang China (c. 1600–1100 BC) may suggest that they also used elephants in warfare. The wild elephant populations of Mesopotamia and China declined quickly because of deforestation and human population growth: by 850 BC the Mesopotamian elephants were extinct, and by 500 BC the Chinese elephants were seriously reduced in numbers and limited to areas well south of the Yellow River.

Capturing elephants from the wild remained a difficult task, but a necessary one given the difficulties of breeding in captivity and the long time required for an elephant to reach sufficient maturity to engage in battle. Sixty-year-old war elephants were always prized as being at the most suitable age for battle service and gifts of elephants of this age were seen as particularly generous. Today an elephant is considered in its prime and at the height of its power between the ages of 25 and 40, yet elephants as old as 80 are used in tiger hunts because they are more disciplined and experienced.

It is commonly thought that the reason all war elephants were male was because of males' greater aggression, but it was instead because a female elephant in battle will run from a male; therefore only males could be used in war, whereas female elephants were more commonly used for logistics.

Indian subcontinent
There is uncertainty as to when elephant warfare first started, but it is widely accepted that it began in ancient India. The early Vedic period did not extensively specify the use of elephants in war. However, in the Ramayana, Indra is depicted as riding either Airavata, a mythological elephant, or on the Uchchaihshravas, as his mounts. Elephants were widely utilized in warfare by the later Vedic period by the 6th century BC. The increased conscription of elephants in the military history of India coincides with the expansion of the Vedic Kingdoms into the Indo-Gangetic Plain suggesting its introduction during the intervening period. The practice of riding on elephants in peace and war, royalty or commoner, was first recorded in the 6th or 5th century BC. This practice is believed to be much older than proper recorded history.

The ancient Indian epics Ramayana and Mahābhārata, dating from 5th–4th century BC, elaborately depict elephant warfare. They are recognized as an essential component of royal and military processions. In ancient India, initially, the army was fourfold (chaturanga), consisting of infantry, cavalry, elephants and chariots. Kings and princes principally ride on chariots, which was considered the most royal, while seldom riding the back of elephants. Although viewed as secondary to chariots by royalty, elephants were the preferred vehicle of warriors, especially the elite ones. While the chariots eventually fell into disuse, the other three arms continued to be valued. Many characters in the epic Mahābhārata were trained in the art. According to the rules of engagement set for the Kurukshetra War two men were to duel utilizing the same weapon and mount including elephants. In the Mahābhārata the akshauhini battle formation consists of a ratio of 1 chariot : 1 elephant : 3 cavalry : 5 infantry soldiers. Many characters in the Mahābhārata were described as skilled in the art of elephant warfare e.g. Duryodhana rides an elephant into battle to bolster the demoralized Kaurava army. Scriptures like the Nikāya and Vinaya Pitaka assign elephants in their proper place in the organization of an army. The Samyutta Nikaya additionally mentions the Gautama Buddha being visited by a 'hatthāroho gāmaṇi'. He is the head of a village community bound together by their profession as mercenary soldiers forming an elephant corp.

Ancient Indian kings certainly valued the elephant in war, some stating that an army without elephants is as despicable as a forest without a lion, a kingdom without a king, or as valor unaided by weapons. The use of elephants further increased with the rise of the Mahajanapadas. King Bimbisara (c. 543 BC), who began the expansion of the Magadha kingdom, relied heavily on his war elephants. The Mahajanapadas would be conquered by the Nanda Empire under the reign of Mahapadma Nanda. Pliny the Elder and Plutarch also estimated the Nanda Army strength in the east as 200,000 infantry, 80,000 cavalry, 8,000 chariots, and 6,000 war elephants. Alexander the Great would come in contact with the Nanda Empire on the banks of the Beas River and was forced to return due to his army's unwillingness to advance. Even if the numbers and prowess of these elephants were exaggerated by historic accounts, elephants were established firmly as war machines in this period.

Chandragupta Maurya (321–297 BC), formed the Maurya Empire, the largest empire to exist in South Asia. At the height of his power, Chandragupta is said to have wielded a military of 600,000 infantry, 30,000 cavalry, 8,000 chariots and 9,000 war elephants besides followers and attendants.

In the Mauryan Empire, the 30-member war office was made up of six boards. The sixth board looked after the elephants, and were headed by Gajadhyaksha. The gajadhyaksha was the superintendent of elephants and his qualifications. The use of elephants in the Maurya Empire as recorded by Chanakya in the Arthashastra. According to Chanakya; catching, training, and controlling war elephants was one of the most important skills taught by the military academies. He advised Chandragupta to set up forested sanctuaries for the wellness of the elephants. Chanakya explicitly conveyed the importance of these sanctuaries. The Maurya Empire would reach its zenith under the reign of Ashoka, who used elephants extensively during his conquest. During the Kalinga War, Kalinga had a standing army of 60,000 infantry, 1000 cavalry and 700 war elephants. Kalinga was notable for the quality of their war elephants which were prized by its neighbors for being stronger. Later the King Kharavela was to restore an independent Kalinga into a powerful kingdom using war elephants as stated in the Hathigumpha inscription or "Elephant Cave" Inscriptions.

Following Indian accounts foreign rulers would also adopt the use of elephants.

The Chola Empire of Tamil Nadu also had a very strong elephant force. The Chola emperor Rajendra Chola had an armored elephant force, which played a major role in his campaigns.

Sri Lanka made extensive use of elephants and also exported elephants with Pliny the Elder stating that the Sri Lankan elephants, for example, were larger, fiercer and better for war than local elephants. This superiority, as well as the proximity of the supply to seaports, made Sri Lanka's elephants a lucrative trading commodity. Sri Lankan history records indicate elephants were used as mounts for kings leading their men in the battlefield, with individual mounts being recorded in history. The elephant Kandula was King Dutugamunu's mount and Maha Pambata, 'Big Rock', the mount of King Ellalan during their historic encounter on the battlefield in 200 BC, for example.

Eastern Asia
Elephants were used for warfare in China by a small handful of southern dynasties. The state of Chu used elephants in 506 BC against Wu by tying torches to their tails and sending them into the ranks of the enemy soldiers, but the attempt failed. In December 554 AD, the Liang dynasty used armoured war elephants, carrying towers, against Western Wei. They were defeated by a volley of arrows. The Southern Han dynasty is the only state in Chinese history to have kept a permanent corps of war elephants. These elephants were able to carry a tower with some ten people on their backs. They were used successfully during the Han invasion of Ma Chu in 948. In 970, the Song dynasty invaded Southern Han and their crossbowmen readily routed the Han elephants on 23 January 971, during the taking of Shao. That was the last time elephants were used in Chinese warfare, although the Wanli Emperor (r. 1572–1620) did keep a herd of elephants capable of carrying a tower and eight men, which he showed to his guests in 1598. These elephants were probably not native to China and were delivered to the Ming dynasty by Southeast Asian countries such as Siam. During the Revolt of the Three Feudatories, the rebels used elephants against the Qing dynasty, but the Qing Bannermen shot them with so many arrows that they "resembled porcupines" and repelled the elephant charge.

"... the soldiers of the first column were attacked by the elephants. The flags of Major-general of the Guards, Walda of the Yellow Banner, and of Lieutenant Ulehi of the Manchu-Mongol cavalry were captured. As the elephants closed in on the encircled soldiers of the second column, the arrows shot by all of my men [into the elephants’ hides] looked like the quills of a porcupine. The elephants fled towards the hills [but] I was greatly alarmed and had a strange feeling. The rebels withdrew from the plain and split into groups [to hide] in the thick forest of the mountain."

- Dzengseo

Chinese armies faced off against war elephants in Southeast Asia, such as during the Sui–Lâm Ấp war (605), Lý–Song War (1075–1077), Ming–Mong Mao War (1386–1388), and Ming–Hồ War (1406–1407). In 605, the Champa kingdom of Lâm Ấp in what is now southern Vietnam used elephants against the invading army of China's Sui dynasty. The Sui army dug pits and lured the elephants into them and shot them with crossbows, causing the elephants to turn back and trample their own army. In 1075, the Song defeated elephants deployed on the borderlands of Đại Việt during the Lý–Song War. The Song forces used scythed polearms to cut the elephants' trunks, causing them to trample their own troops. During the Mong Mao campaign, the elephants were routed by an assortment of gunpowder projectiles. In the war against the Hồ dynasty, Ming troops covered their horses with lion masks to scare the elephants and shot them with firearms. The elephants all trembled with fear and were wounded by the guns and arrows, causing the Viet army to panic.

Achaemenid Persia, Macedonia and Hellenistic Greek states

From India, military thinking on the use of war elephants spread westwards to the Persian Achaemenid Empire, where they were used in several campaigns. They in turn came to influence the campaigns of Alexander the Great, king of Macedonia in Hellenistic Greece. The first confrontation between Europeans and the Persian war elephants occurred at Alexander's Battle of Gaugamela (331 BC), where the Persians deployed fifteen elephants. These elephants were placed at the centre of the Persian line and made such an impression on Alexander's army that he felt the need to sacrifice to Phobos, the God of Fear, the night before the battle – but according to some sources the elephants ultimately failed to deploy in the final battle owing to their long march the day before. Alexander won resoundingly at Gaugamela, but was deeply impressed by the enemy elephants and took these first fifteen into his own army, adding to their number during his capture of the rest of Persia.

By the time Alexander reached the borders of India five years later, he had a substantial number of elephants under his own command. When it came to defeating Porus, who ruled in what is now Punjab, Pakistan, Alexander found himself facing a considerable force of between 85 and 100 war elephants at the Battle of the Hydaspes. Preferring stealth and mobility to sheer force, Alexander manoeuvered and engaged with just his infantry and cavalry, ultimately defeating Porus' forces, including his elephant corps, albeit at some cost. Porus for his part placed his elephants individually, at long intervals from each other, a short distance in front of his main infantry line, in order to scare off Macedonian cavalry attacks and aid his own infantry in their struggle against the phalanx. The elephants caused many losses with their tusks fitted with iron spikes or by lifting the enemies with their trunks and trampling them.

Arrian described the subsequent fight: "[W]herever the beasts could wheel around, they rushed forth against the ranks of infantry and demolished the phalanx of the Macedonians, dense as it was."

The Macedonians adopted the standard ancient tactic for fighting elephants, loosening their ranks to allow the elephants to pass through and assailing them with javelins as they tried to wheel around; they managed to pierce the unarmoured elephants' legs. The panicked and wounded elephants turned on the Indians themselves; the mahouts were armed with poisoned rods to kill the beasts but were slain by javelins and archers.

Looking further east again, however, Alexander could see that the emperors and kings of the Nanda Empire and Gangaridai could deploy between 3,000 and 6,000 war elephants. Such a force was many times larger than the number of elephants employed by the Persians and Greeks, which probably discouraged Alexander's army and effectively halted their advance into India. On his return, Alexander established a force of elephants to guard his palace at Babylon, and created the post of elephantarch to lead his elephant units.

The successful military use of elephants spread further. The successors to Alexander's empire, the Diadochi, used hundreds of Indian elephants in their wars, with the Seleucid Empire being particularly notable for their use of the animals, still being largely brought from India. Indeed, the Seleucid–Mauryan war of 305–303 BC ended with the Seleucids ceding vast eastern territories in exchange for 500 war elephants – a small part of the Mauryan forces, which included up to 9000 elephants by some accounts. The Seleucids put their new elephants to good use at the Battle of Ipsus four years later, where they blocked the return of the victorious Antigonid cavalry, allowing the latter's phalanx to be isolated and defeated.

The first use of war elephants in Europe was made in 318 BC by Polyperchon, one of Alexander's generals, when he besieged Megalopolis in the Peloponnesus during the wars of the Diadochi. He used 60 elephants brought from Asia with their mahouts. A veteran of Alexander's army, named Damis, helped the besieged Megalopolitians to defend themselves against the elephants and eventually Polyperchon was defeated. Those elephants were subsequently taken by Cassander and transported, partly by sea, to other battlefields in Greece. It is assumed that Cassander constructed the first elephant transport sea vessels. Some of the elephants died of starvation in 316 BC in the besieged city of Pydna in Macedonia. Others of Polyperchon's elephants were used in various parts of Greece by Cassander.

Although the use of war elephants in the western Mediterranean is most famously associated with the wars between Carthage and Roman Republic, the introduction of war elephants there was primarily the result of an invasion by Hellenistic era Epirus across the Adriatic Sea. King Pyrrhus of Epirus brought twenty elephants to attack Roman Italy at the battle of Heraclea in 280 BC, leaving some fifty additional animals, on loan from Ptolemaic Pharaoh Ptolemy II, on the mainland. The Romans were unprepared for fighting elephants, and the Epirot forces routed the Romans. The next year, the Epirots again deployed a similar force of elephants, attacking the Romans at the battle of Asculum. This time the Romans came prepared with flammable weapons and anti-elephant devices: these were ox-drawn wagons, equipped with long spikes to wound the elephants, pots of fire to scare them, and accompanying screening troops who would hurl javelins at the elephants to drive them away. A final charge of Epirot elephants won the day again, but this time Pyrrhus had suffered very heavy casualties – a Pyrrhic victory.

The Seleucid king Antiochus V Eupator, whose father and he vied with Ptolemaic Egypt's ruler Ptolemy VI over the control of Syria, invaded Judea in 161 BC with eighty elephants (others say thirty-two), some clad with armored breastplates, in an attempt to subdue the Jews who had sided with Ptolemy. In the ensuing battle, near certain mountainous straights adjacent to Beth Zachariah, Eleazar the Hasmonaean attacked the largest of the elephants, piercing its underside and bringing the elephant down upon himself.

North Africa

The North African elephant was a significant animal in Nubian culture. They were depicted on the walls of temples and on Meroitic lamps. Kushite kings also utilize war elephants, which are believed to have been kept and trained in the "Great Enclosure" at Musawwarat al-Sufa. The Kingdom of Kush provided these war elephants to the Egyptians, Ptolemies and Syrians.

The Ptolemaic Egypt and the Punics began acquiring African elephants for the same purpose, as did Numidia and the Kingdom of Kush. The animal used was the North African elephant (Loxodonta africana pharaohensis) which would become extinct from overexploitation. These animals were smaller and harder to tame, and could not swim deep rivers compared with the Asian elephants used by the Seleucid Empire on the east of the Mediterranean region, particularly Syrian elephants, which stood 2.5 - 3.5 m at the shoulder. It is likely that at least some Syrian elephants were traded abroad. The favorite, and perhaps last surviving, elephant of Hannibal's crossing of the Alps was an impressive animal named Surus ("the Syrian"), which may have been of Syrian stock, though the evidence remains ambiguous.

Since the late 1940s, a strand of scholarship has argued that the African forest elephants used by Numidia, the Ptolemies and the military of Carthage did not carry howdahs or turrets in combat, perhaps owing to the physical weakness of the species. Some allusions to turrets in ancient literature are certainly anachronistic or poetic invention, but other references are less easily discounted. There is explicit contemporary testimony that the army of Juba I of Numidia included turreted elephants in 46 BC. This is confirmed by the image of a turreted African elephant used on the coinage of Juba II. This also appears to be the case with Ptolemaic armies: Polybius reports that at the battle of Raphia in 217 BC the elephants of Ptolemy IV carried turrets; these elephants were significantly smaller than the Asian elephants fielded by the Seleucids and so presumably African forest elephants. There is also evidence that Carthaginian war elephants were furnished with turrets and howdahs in certain military contexts.

Farther south, tribes would have had access to the African savanna elephant (Loxodonta africana oxyotis). Although much larger than either the African forest elephant or the Asian elephant, these proved difficult to tame for war purposes and were not used extensively. Asian elephants were traded westwards to the Mediterranean markets with Sri Lankan elephants being particularly preferred for war.

Perhaps inspired by the victories of Pyrrhus of Epirus, Carthage developed its own use of war elephants and deployed them extensively during the First and Second Punic Wars. The performance of the Carthaginian elephant corps was rather mixed, illustrating the need for proper tactics to take advantage of the elephant's strength and cover its weaknesses. At Adyss in 255 BC, the Carthaginian elephants were ineffective due to the terrain, while at the battle of Panormus in 251 BC the Romans' velites were able to terrify the Carthaginian elephants being used unsupported, which fled from the field. At the battle of Tunis however the charge of the Carthaginian elephants helped to disorder the legions, allowing the Carthaginian phalanx to stand fast and defeat the Romans. During the Second Punic War, Hannibal famously led an army of war elephants across the Alps, although many of them perished in the harsh conditions. The surviving elephants were successfully used in the battle of Trebia, where they panicked the Roman cavalry and Gallic allies. The Romans eventually developed effective anti-elephant tactics, leading to Hannibal's defeat at his final battle of Zama in 202 BC; his elephant charge, unlike the one at the battle of Tunis, was ineffective because the disciplined Roman maniples simply made way for them to pass.

Rome

Rome brought back many elephants at the end of the Punic Wars, and used them in its campaigns for many years afterwards. The conquest of Greece saw many battles in which the Romans deployed war elephants, including the invasion of Macedonia in 199 BC, the battle of Cynoscephalae 197 BC, the battle of Thermopylae, and the battle of Magnesia in 190 BC, during which Antiochus III's fifty-four elephants took on the Roman force of sixteen. In later years the Romans deployed twenty-two elephants at Pydna in 168 BC. The role of the elephant force at Cynoscephalae was particularly decisive, as their quick charge shattered the unformed Macedonian left wing, allowing the Romans to encircle and destroy the victorious Macedonian right. A similar event also occurred at Pydna. The Romans' successful use of war elephants against the Macedonians might be considered ironic, given that it was Pyrrhus who first taught them the military potential of elephants.

Elephants also featured throughout the Roman campaign against the Lusitanians and Celtiberians in Hispania. During the Second Celtiberian War, Quintus Fulvius Nobilior was helped by ten elephants sent by king Masinissa of Numidia. He deployed them against the Celtiberian forces of Numantia, but a falling stone hit one of the elephants, which panicked and frightened the rest, turning them against the Roman forces. After the subsequent Celtiberian counterattack, the Romans were forced to withdraw. Later, Quintus Fabius Maximus Servilianus marched against Viriathus with another ten elephants sent by king Micipsa. However, the Lusitanian style of ambushes in narrow terrains ensured his elephants did not play an important factor in the conflict, and Servilianus was eventually defeated by Viriathus in the city of Erisana.

Famously, the Romans used a war elephant in their first invasion of Britain, one ancient writer recording that "Caesar had one large elephant, which was equipped with armor and carried archers and slingers in its tower. When this unknown creature entered the river, the Britons and their horses fled and the Roman army crossed over" – although he may have confused this incident with the use of a similar war elephant in Claudius' final conquest of Britain. At least one elephantine skeleton with flint weapons that has been found in England was initially misidentified as these elephants, but later dating proved it to be a mammoth skeleton from the Stone Age.

In the African campaign of the Roman civil war of 49–45 BC, the army of Metellus Scipio used elephants against Caesar's army at the battle of Thapsus. Scipio trained his elephants before the battle by aligning the elephants in front of slingers that would throw rocks at them, and another line of slingers at the elephants' rear to perform the same, in order to propel the elephants only in one direction, preventing them turning their backs because of frontal attack and charging against his own lines, but the author of De Bello Africano admits of the enormous effort and time required to accomplish this.

By the time of Claudius however, such animals were being used by the Romans in single numbers only – the last significant use of war elephants in the Mediterranean was against the Romans at the battle of Thapsus, 46 BC, where Julius Caesar armed his fifth legion (Alaudae) with axes and commanded his legionaries to strike at the elephant's legs. The legion withstood the charge, and the elephant became its symbol. Thapsus was the last significant use of elephants in the West. The remainder of the elephants seemed to have been thrown into panic by Caesar's archers and slingers.

Parthia and Sassanian Persia

The Parthian Empire occasionally used war elephants in their battles against the Roman Empire, having done so in at least one war against the Romans but elephants were of substantial importance in the army of the subsequent Sassanid Empire. The Sasanian war elephants are recorded in engagements against the Romans, such as during Julian's invasion of Persia. Other examples include the Battle of Vartanantz in 451 AD, at which the Sassanid elephants terrified the Armenians, and the Battle of al-Qādisiyyah of 636 AD, in which a unit of thirty-three elephants was used against the invading Arab Muslims, in which battle the war elephants proved to be a "double-edged sword".

The Sassanid elephant corps held primacy amongst the Sassanid cavalry forces and was recruited from India. The elephant corps was under a special chief, known as the Zend−hapet, literally meaning "Commander of the Indians", either because the animals came from that country, or because they were managed by natives of Hindustan. The Sassanid elephant corps was never on the same scale as others further east, however, and after the fall of the Sassanid Empire the use of war elephants died out in the region.

Aksumite Empire
The Kingdom of Aksum in what is now Ethiopia and Eritrea made use of war elephants in 525 AD during the invasion of the Himyarite Kingdom in the Arabian peninsula. The war elephants used by the Aksumite army consisted of African savannah elephants, a significantly larger and more temperamental species of elephant. War elephants were again put to use by an Aksumite army in the year 570 in a military expedition against the Quraysh of Mecca.

Middle Ages

The Kushan Empire conquered most of Northern India. The empire adopted war elephants when levying troops as they expanded into the Indian subcontinent. The Weilüe describes how the population of Eastern India rode elephants into battle, but currently they provide military service and taxes to the Yuezhi (Kushans). The Hou Hanshu additionally describes the Kushan as acquiring riches including elephants as part of their conquests. The emperor Kanishka assembled a great army from his subject nations, including elephants from India. He planned on attacking the Tarim Kingdoms, and sent a vanguard of Indian troops led by white elephants. However, when crossing the Pamir Mountains the elephants and horses in the vanguard were unwilling to advance. Kanishka is then said to have had a religious revelation and rejected violence.

The Gupta Empire demonstrated extensive use of elephants in war and greatly expanded under the reign of Samudragupta. Local squads which each consisted of one elephant, one chariot, three armed cavalrymen, and five foot soldiers protected Gupta villages from raids and revolts. In times of war, the squads joined together to form a powerful imperial army. The Gupta Empire employed 'Mahapilupati', a position as an officer in charge of elephants. Emperors such as Kumaragupta struck coins depicted as elephant riders and lion slayers.

Harsha established hegemony over most of North India. The Harshacharita composed by Bāṇabhaṭṭa describes the army under the rule of Harsha. Much like the Gupta Empire, his military consisted of infantry, cavalry, and elephants. Harsha received war elephants as tribute and presents from vassals. Some elephants were also obtained by forest rangers from the jungles. Elephants were additionally taken from defeated armies. Bana additionally details the diet of the elephants, recording that they each consumed 600 pounds of fodder consisting of trees with mangos and sugarcanes.

The Chola dynasty and the Western Chalukya Empire maintained a large number of war elephants in the 11th and 12th century. The war elephants of the Chola dynasty carried on their backs fighting towers which were filled with soldiers who would shoot arrows at long range. The army of the Pala Empire was noted for its huge elephant corps, with estimates ranging from 5,000 to 50,000.

The Ghaznavids were the first amongst the Islamic dynasties to incorporate war elephants into their tactical theories. They also used a large number of elephants in their battles. The Ghaznavids acquired their elephants as tribute from the Hindu princes and as war plunder. The sources usually list the number of beasts captured, and these frequently ran into hundreds, such as 350 from Qanauj and 185 from Mahaban in 409/1018-19, and 580 from the Raja Ganda in 410/1019-20. Utbi records that the Thanesar expedition of 405/1014-15 was provoked by Mahmad's desire to get some of the special breed of Sri lankan breed of elephants excellent in war

In 1526, Babur, a descendant of Timur, invaded India and established the Mughal Empire. Babur introduced firearms and artillery into Indian warfare. He destroyed the army of Ibrahim Lodi at the First Battle of Panipat and the army of Rana Sanga in 1527 at the Battle of Khanua. The great Moghul Emperor Akbar (r. 1556–1605 AD) had 32,000 elephants in his stables. Jahangir, (reigned 1605–1627 A.D.) was a great connoisseur of elephants. He increased the number of elephants in service. Jahangir was stated to have 113,000 elephants in captivity: 12,000 in active army service, 1,000 to supply fodder to these animals, and another 100,000 elephants to carry courtiers, officials, attendants and baggage.

King Rajasinghe I laid siege to the Portuguese fort at Colombo, Sri Lanka, in 1558 with an army containing 2,200 elephants, used for logistics and siege work. The Sri Lankans had continued their proud traditions in capturing and training elephants from ancient times. The officer in charge of the royal stables, including the capture of elephants, was called the Gajanayake Nilame, while the post of Kuruve Lekham controlled the Kuruwe or elephant men. The training of war elephants was the duty of the Kuruwe clan who came under their own Muhandiram, a Sri Lankan administrative post.

In Islamic history there is a significant event known as the ‘Am al-Fil (عَـام الـفـيـل, "Year of the Elephant"), approximately equating to 570 AD. At that time Abraha, the Christian ruler of Yemen, marched upon the Ka‘bah in Mecca, intending to demolish it. He had a large army, which included one or more elephants (as many as eight, in some accounts). However, the (single or lead) elephant, whose name was 'Mahmud', is said to have stopped at the boundary around Mecca, and refused to enter – which was taken by both the Meccans and their Yemenite foes as a serious omen. According to Islamic tradition, it was in this year that Muhammad was born.

In the Middle Ages, elephants were seldom used in Europe. Charlemagne took his one elephant, Abul-Abbas, when he went to fight the Danes in 804, and the Crusades gave Holy Roman Emperor Frederick II the opportunity to capture an elephant in the Holy Land, the same animal later being used in the capture of Cremona in 1214, but the use of these individual animals was more symbolic than practical, especially when contrasting food and water consumption of elephants in foreign lands and the harsh conditions of the crusades.

The Mongols faced war-elephants in Khorazm, Burma, Siam, Vietnam, Khmer and India throughout the 13th century. Despite their unsuccessful campaigns in Vietnam and India, the Mongols defeated the war elephants outside Samarkand by using catapults and mangonels, and during the Mongol invasions of Burma in 1277–1287 and 1300–1302 by showering arrows from their famous composite bows. Genghis and Kublai both retained captured elephants as part of their entourage. Another central Asian invader, Timur faced similar challenges a century later. In 1398 Timur's army faced more than one hundred Indian elephants in battle and almost lost because of the fear they caused amongst his troops. Historical accounts say that the Timurids ultimately won by employing an ingenious strategy: Timur tied flaming straw to the back of his camels before the charge. The smoke made the camels run forward, scaring the elephants, who crushed their own troops in their efforts to retreat. Another account of the campaign by Ahmed ibn Arabshah reports that Timur used oversized caltrops to halt the elephants' charge. Later, the Timurid leader used the captured animals against the Ottoman Empire.

In Southeast Asia, the powerful Khmer Empire had come to regional dominance by the 9th century AD, drawing heavily on the use of war elephants. Uniquely, the Khmer military deployed double cross-bows on the top of their elephants. With the collapse of Khmer power in the 15th century, the successor region powers of Burma (now Myanmar) and Siam (now Thailand) also adopted the widespread use of war elephants. In many battles of the period it was the practice for leaders to fight each other personally in elephant duels. One famous battle occurred when the Burmese army attacked Siam's Kingdom of Ayutthaya. The war may have been concluded when the Burmese crown prince Mingyi Swa was killed by Siamese King Naresuan in personal combat on elephant in 1593. However, this duel may be apocryphal.

In Thailand, the king or general rode on the elephant's neck and carried ngaw, a long pole with a sabre at the end, plus a metal hook for controlling the elephant. Sitting behind him on a howdah, was a signaller, who signalled by waving of a pair of peacock feathers. Above the signaller was the chatras, consisting of progressively stacked circular canopies, the number signifying the rank of the rider. Finally, behind the signaller on the elephant's back, was the steerer, who steered via a long pole. The steerer may have also carried a short musket and a sword.

In Malaysia, 20 elephants battled the Portuguese during the Capture of Malacca (1511).

The Chinese continued to reject the use of war elephants throughout the period, with the notable exception of the Southern Han during the 10th century AD – the "only nation on Chinese soil ever to maintain a line of elephants as a regular part of its army". This anomaly in Chinese warfare is explained by the geographical proximity and close cultural links of the southern Han to Southeast Asia. The military officer who commanded these elephants was given the title "Legate Digitant and Agitant of the Gigantic Elephants". Each elephant supported a wooden tower that could allegedly hold ten or more men. For a brief time, war elephants played a vital role in Southern Han victories such as the invasion of Chu in 948 AD, but the Southern Han elephant corps were ultimately soundly defeated at Shao in 971 AD, defeated by crossbow shooting from troops of the Song Dynasty. As one academic has put it, "thereafter this exotic introduction into Chinese culture passed out of history, and the tactical habits of the North prevailed". However, as late as the Ming dynasty in as far north as Beijing, there were still records of elephants being used in Chinese warfare, namely in 1449 where a Vietnamese contingent of war elephants helped the Ming Dynasty defend the city from the Mongols.

Modern era

With the advent of gunpowder warfare in the late 15th century, the balance of advantage for war elephants on the battlefield began to change. While muskets had limited impact on elephants, which could withstand numerous volleys, cannon fire was a different matter entirely – an animal could easily be knocked down by a single shot. With elephants still being used to carry commanders on the battlefield, they became even more tempting targets for enemy artillery.

Nonetheless, in south-east Asia the use of elephants on the battlefield continued up until the end of the 19th century. One of the major difficulties in the region was terrain, and elephants could cross difficult terrain in many cases more easily than horse cavalry. Burmese forces used war elephants against the Chinese in the Sino-Burmese War where they routed the Chinese cavalry. The Burmese used them again during the Battle of Danubyu during the First Anglo-Burmese War, where the elephants were easily repulsed by Congreve rockets deployed by British forces. The Siamese Army continued utilising war elephants armed with jingals up until the Franco-Siamese conflict of 1893, while the Vietnamese used them in battle as late as 1885, during the Sino-French War. During the mid to late 19th century, British forces in India possessed specialised elephant batteries to haul large siege artillery pieces over ground unsuitable for oxen.

Into the 20th century, military elephants were used for non-combat purposes in the Second World War, particularly because the animals could perform tasks in regions that were problematic for motor vehicles. Sir William Slim, commander of the XIVth Army wrote about elephants in his introduction to Elephant Bill: "They built hundreds of bridges for us, they helped to build and launch more ships for us than Helen ever did for Greece. Without them our retreat from Burma would have been even more arduous and our advance to its liberation slower and more difficult." Military elephants were used as late as the Vietnam War.

Elephants were as of 2017 being used by the Kachin Independence Army for an auxiliary role. Elephants are now more valuable to many armies in failing states for their ivory than as transport, and many thousands of elephants have died during civil conflicts due to poaching. They are classed as a pack animal in a U.S. Special Forces field manual issued as recently as 2004, but their use by U.S. personnel is discouraged because elephants are endangered.

Tactical use

There were many military purposes for which elephants could be used. In battle, war elephants were usually deployed in the centre of the line, where they could be useful to prevent a charge or to conduct one of their own. Their sheer size and their terrifying appearance made them valued heavy cavalry. Off the battlefield they could carry heavy materiel, and with a top speed of approximately 30 km/h provided a useful means of transport, before mechanized vehicles rendered them mostly obsolete.

In addition to charging, elephants could provide a safe and stable platform for archers to shoot arrows in the middle of the battlefield, from which more targets could be seen and engaged. The driver, called a mahout, was responsible for controlling the animal, who often also carried weapons himself, like a chisel-blade and a hammer (to kill his own mount in an emergency). Elephants were sometimes further enhanced with their own weaponry and armour as well. In India and Sri Lanka, heavy iron chains with steel balls at the end were tied to their trunks, which the animals were trained to swirl menacingly and with great skill. Numerous cultures designed specialized equipment for elephants, like tusk swords and a protective tower on their backs, called howdahs. The late sixteenth century saw the introduction of culverins, jingals and rockets against elephants, innovations that would ultimately drive these animals out of active service on the battlefield.

Besides the dawn of more efficient means of transportation and weaponry, war elephants also had clear tactical weaknesses that lead to their eventual retirement. After sustaining painful wounds, or when their driver was killed, elephants had the tendency to panic, often causing them to run amok indiscriminately, making casualties on either side. Experienced Roman infantrymen often tried to sever their trunks, causing instant distress, and possibly leading the elephant to flee back into its own lines. Fast skirmishers armed with javelins were also used by the Romans to drive them away, as well as flaming objects or a stout line of long spears, such as Triarii. Another method for disrupting elephant units in classical antiquity was the deployment of war pigs. Ancient writers believed that elephants could be "scared by the smallest squeal of a pig". Some warlords, however, interpreted this expression literally. At the siege of Megara during the Diadochi wars, for example, the Megarians reportedly poured oil on a herd of pigs, set them alight, and drove them towards the enemy's massed war elephants, which subsequently bolted in terror.

The value of war elephants in battle remains a contested issue. In the 19th century, it was fashionable to contrast the western, Roman focus on infantry and discipline with the eastern, exotic use of war elephants that relied merely on fear to defeat their enemy. One writer commented that war elephants "have been found to be skittish and easily alarmed by unfamiliar sounds and for this reason they were found prone to break ranks and flee". Nonetheless, the continued use of war elephants for several thousand years attests to their enduring value to the historical battlefield commander.

Cultural legacy
The use of war elephants over the centuries has left a deep cultural legacy in many countries. Many traditional war games incorporate war elephants. There is piece in chess called Elephant. While Englishmen call that piece bishop, it is called Gajam in Sanskrit. In Malayalam, it is called Aana (ആന), meaning elephant. In Russian, too, it is an elephant (Слон). In Bengali, the bishop is called hati, Bengali for "elephant". It is called an elephant in Chinese chess. In Arabic – and derived from it, in Spanish – the bishop piece is called al-fil, Arabic for "elephant".

In the Japanese game shogi, there used to be a piece known as the "Drunken Elephant"; it was, however, dropped by order of the Emperor Go-Nara and no longer appears in the version played in today's Japan.

Elephant armour, originally designed for use in war, is today usually only seen in museums. One particularly fine set of Indian elephant armour is preserved at the Leeds Royal Armouries Museum, while Indian museums across the sub-continent display other fine pieces. The architecture of India also shows the deep impact of elephant warfare over the years. War elephants adorn many military gateways, such as those at Lohagarh Fort for example, while some spiked, anti-elephant gates still remain, for example at Kumbhalgarh fort. Across India, older gateways are invariably much higher than their European equivalents, in order to allow elephants with howdahs to pass through underneath.

War elephants also remain a popular artistic trope, either in the Orientalist painting tradition of the 19th century, or in literature following Tolkien, who popularised a fantastic rendition of war elephants in the form of 'oliphaunts' or mûmakil.

In popular culture
Hathi from The Jungle Book by Rudyard Kipling is a former Indian war elephant who pulled heavy artillery for the British Indian Army. Kala-Nag from Toomai of the Elephants performed similar duties during the First Anglo-Afghan War.

Numerous strategy video games feature elephants as special units, usually available only to specific factions or requiring special resources. These include Age of Empires, Celtic Kings: The Punic Wars, the Civilization series, the Total War series, Imperator: Rome, and Crusader Kings III.

In the 2004 film Alexander scene of the Battle of Hydaspes depicts war elephants fighting against the Macedonian phalanx.

In the 2017 video game Assassin's Creed Origins, they are distributed around the map as boss fights.

In The Lord of the Rings: The Return of the King, Mûmakil (or Oliphaunts) are fictional giant elephant-like creatures used by Sauron, and his Haradrim army in the Battle of the Pelennor Fields.

In Genndy Tartakovsky's Primal, an episode features war elephants fighting against Egyptians.

In Horizon Forbidden West, there are machines called Tremortusks, which are suited for combat and are based on war elephants.

It is also the nickname of Thai national football teams such as the Thailand national football team.

General and cited references

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title: War elephant


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List of presidents of Cameroon

This is a list of presidents of Cameroon since the country gained independence from France in 1960 to the present day.A total of two people have served as President of Cameroon.The current President of Cameroon is Paul Biya, since 6 November 1982.

List of officeholders
{{legend||Cameroonian Union (UC)|border=1px solid #AAAAAA}} {{legend||Cameroonian National Union (UNC)|border=1px solid #AAAAAA}} {{legend||Cameroon People's Democratic Movement (RDPC)|border=1px solid #AAAAAA}}
 * Political parties

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

title: List of presidents of Cameroon


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Advanced Authoring Format

The Advanced Authoring Format (AAF) is a file format for professional cross-platform data interchange, designed for the video post-production and authoring environment. It was created by the Advanced Media Workflow Association (AMWA), and is now being standardized through the Society of Motion Picture and Television Engineers (SMPTE).

History
AAF was originally created by the AMWA, formerly the AAF Association Inc., a trade association created to develop and promote adoption of specifications and technologies, such as AAF, Material Exchange Format (MXF), and Service-oriented architecture (SOA), to facilitate the deployment and operation of efficient media workflows. Technical work of the AMWA is through projects that aim to improve compatibility between AAF, Broadcast Exchange Format (BXF), MXF and XML. The current projects fall into three categories: data models, interface specifications, and application specifications.

AAF was created to help address the problem of multi-vendor, cross-platform interoperability for computer-based digital video production.

The AAF Object Model is now being standardized through SMPTE, including a better definition of the mapping between MXF and AAF essence.

Usage
Capabilities of AAF include the following:

 * Allows complex relationships to be described in terms of an object model.
 * Facilitates the interchange of metadata and/or program content.
 * Provides a way to track the history of a piece of program content from its source elements through final production.
 * Makes downstream rendering possible (with appropriate equipment).
 * Provides a convenient way to "wrap" all elements of a project together for archiving.

There are two kinds of data that can be interchanged using AAF:

 * Essence Data: Audio (including music), video, image, graphics, text, animation, and other forms of multimedia data. So named because they are the essential data within a multimedia program that can be perceived directly by the audience.
 * Metadata: Data that provides information on how to combine or modify individual sections of essence data, or that provides supplementary information about essence data. The metadata in an AAF file can provide the information needed to combine and modify the sections of essence data in the AAF file to produce a complete multimedia program.

By preserving source referencing, and abstracting the creative decisions that are made, AAF tries to improve workflow and simplify project management.

AAF's rich data model combining metadata and various types of essence has led to its use in non-broadcast applications as well. For example, AAF has been adopted by the DoD/IC Motion Imagery Standards Board (MISB) for their Aerial Surveillance and Photogrammetry Applications standard (ASPA).

Elements of AAF
The core elements of the AAF specification include:

 * The AAF Object Specification, which defines the structured container by which AAF stores essence data and metadata using an object-oriented model. It defines the logical contents of the objects and the rules for how the objects relate to each other.
 * The AAF Low-Level Container Specification, which describes how each object is stored on disk. It uses Structured Storage, a file storage system developed by Microsoft, to store the objects on disk.
 * The AAF API Specification, which defines how software engineers can write applications.
 * The AAF Reference Implementation, which implements both these specifications in a completely cross-platform manner.
 * The AAF Software Development Kit (SDK), which includes developer utilities and validation test suites.
 * The AAF Example software, which demonstrates how to use the AAF SDK to produce AAF files.
 * The AAF Example files, created by working AAF implementations.

Differences from MXF
AAF is designed to be a data representation of works in progress, as compared to Material Exchange Format (MXF), which is for exchanging finished media products. While MXF uses a Key Length Value (KLV) format for storage, AAF uses the Microsoft Structured Storage system.

MXF was developed as a subtype of the AAF data model, under a zero-divergence policy, which allows for workflows that mix AAF and MXF. Specifically, all MXF metadata can be understood by AAF, but not all AAF metadata can be understood by MXF (and would be filtered out during encoding as a result).

title: Advanced Authoring Format


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List of presidents of Cape Verde

This article lists the presidents of Cape Verde, an island country in the Atlantic Ocean off the coast of West Africa, since the establishment of the office of president in 1975. Aristides Pereira was the first person to hold the office, taking effect on 8 July 1975. The incumbent is José Maria Neves, having taken office on 9 November 2021.

Term limits
As of 2021, there is a two-term limit for the president in the Constitution of Cape Verde. The first president for whom the term limits applied was Monteiro in 2001.

List of officeholders
{{legend||African Party for the Independence of Guinea and Cape Verde (PAIGC)|border=1px solid #aaa}} {{legend||African Party for the Independence of Cape Verde (PAICV)|border=1px solid #aaa}} {{legend||Movement for Democracy (MpD)|border=1px solid #AAAAAA}}
 * Political parties

title: List of presidents of Cape Verde


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Honey bee life cycle

The honey bee life cycle, here referring exclusively to the domesticated Western honey bee, depends greatly on their social structure.

Honey bee colony life
Unlike a bumble bee colony or a paper wasp colony, the life of a honey bee colony is perennial. The three types of honey bees in a hive are: queens (egg-producers), workers (non-reproducing females), and drones (males whose main duty is to find and mate with a queen). Unlike the worker bees, drones do not sting. Honey bee larvae hatch from eggs in three to four days. They are then fed by worker bees and develop through several stages in hexagonal cells made of beeswax. Cells are capped by worker bees when the larva pupates. Queens and drones are larger than workers, so require larger cells to develop. A colony may typically consist of tens of thousands of individuals.

While some colonies live in hives provided by humans, so-called "wild" colonies (although all honey bees remain wild, even when cultivated and managed by humans) typically prefer a nest site that is clean, dry, protected from the weather, about 20 L in volume with a 4–6 cm2 entrance about 3 m above the ground, and preferably facing south or south-east (in the Northern Hemisphere) or north or north-east (in the Southern Hemisphere).

Development
Development from egg to emerging bee varies among queens, workers, and drones. Queens emerge from their cells in 15–16 days, workers in 21 days, and drones in 24 days. Only one queen is usually present in a hive. New virgin queens develop in enlarged cells through differential feeding of royal jelly by workers. When the existing queen ages or dies or the colony becomes very large, a new queen is raised by the worker bees. When the hive is too large, the old queen will take half the colony with her in a swarm. This occurs a few days prior to the new queen emerging. If several queens emerge they will begin piping (a high buzzing noise) signaling their location for the other virgin queens to come fight. Once one has eliminated the others, she will go around the hive chewing the sides of any other queen cells and stinging and killing the pupae. The queen takes one or several nuptial flights to mate with drones from other colonies, which die after mating. After mating, the queen begins laying eggs. A fertile queen is able to lay fertilized or unfertilized eggs. Each unfertilized egg contains a unique combination of 50% of the queen's genes and develops into a (haploid) drone. The fertilized eggs develop into either (diploid) workers or queens (if fed exclusively royal jelly).

Every honey bee (Apis mellifera) in a hive exists to perform specific duties determined by their sex and age. Like every member of its colony, the nurse honey bee plays a vital role in the survival of its hive. Nurse bees are charged with the care and feeding of the queen and the next generation.

The average lifespan of a queen is three to four years; drones usually die upon mating or are expelled from the hive before the winter; and workers may live for a few weeks in the summer and several months in areas with an extended winter.

The weight progression of the worker egg, larva:

title: Honey bee life cycle


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AAF

AAF may refer to:

Aviation

 * Aigle Azur (ICAO code), a French airline
 * Apalachicola Regional Airport (IATA code), in Apalachicola, Florida

Military

 * Albanian Armed Forces
 * Algerian Air Force
 * Afghan Air Force
 * Afghan Armed Forces
 * Army Air Field, an operating base for the United States Army Aviation Branch
 * Auxiliary Air Force, the original name of the Royal Auxiliary Air Force of the United Kingdom
 * United States Army Air Forces, the precursor to the U.S. Air Force

Organizations

 * Aboriginal-Australian Fellowship, a Sydney-based Indigenous rights organisation, 1956−1969
 * Alliance of American Football, a defunct 2019 United States professional American football league
 * Amateur Athletic Foundation, the former name of the LA84 Foundation, a Los Angeles-based nonprofit
 * American Advertising Federation, a U.S. trade association
 * Animals Asia Foundation, a Hong Kong-based charity
 * Association of Adventist Forums, the former name of Adventist Forums, a Seventh-day Adventist group

Technology

 * Advanced Authoring Format, an industry standard for high-end exchange of video project data
 * Anti-aliasing filter, a filter used to restrict the bandwidth of a signal

Other uses

 * 2-Acetylaminofluorene, a biochemical tool
 * Alien Ant Farm, an alternative rock band
 * All Aboard Florida, the Florida East Coast Industries subsidiary that developed Brightline, a passenger rail service in Florida
 * Aranadan language, a Dravidian language of India
 * "Advance Australia Fair", the national anthem of Australia
 * Applied Art Forms (brand), a fashion brand launched by Scottish musician Guy Berryman
 * American Air Filter, today a part of HVAC-equipment-maker Daikin

title: AAF


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List of heads of state of the Central African Republic

This article lists the heads of state of the Central African Republic. There have been seven heads of state of the Central African Republic and the Central African Empire since independence was obtained from the French on 13 August 1960. This list includes not only those persons who were sworn into office as President of the Central African Republic but also those who served as de facto heads of state.

Jean-Bédel Bokassa served as a de facto head of state (and also reigned as Emperor from 1976 to 1979), while David Dacko (who served as de facto head of state from 1979 to 1981), André Kolingba, Ange-Félix Patassé, and François Bozizé were elected into office at some point during their tenure. To date, Kolingba is the only former head of state of the Central African Republic to voluntarily step down from the office through a democratic process, following the 1993 general election.

The current President of the Central African Republic is Faustin-Archange Touadéra, since 30 March 2016.

Succession
Before the adoption of the 2023 constitution, the President of the National Assembly was the constitutional successor of the president in the event of a vacancy.

Term
Before the adoption of the 2023 constitution, there was a two-term limit for the president in the Constitution of the Central African Republic. The term limit was not met by any president. The constitution of 2023 removed term-limits and extended the presidential term from five years to seven years.

List of officeholders
{{legend||Movement for the Social Evolution of Black Africa (MESAN)|border=1px solid #AAAAAA}} {{legend||Central African Democratic Union (UDC)|border=1px solid #AAAAAA}} {{legend||Central African Democratic Rally (RDC)|border=1px solid #AAAAAA}} {{legend||Movement for the Liberation of the Central African People (MLPC)|border=1px solid #AAAAAA}} {{legend|CornflowerBlue|Rally for the Republic (RPR)|border=1px solid #AAAAAA}} {{legend||United Hearts Movement (MCU)|border=1px solid #AAAAAA}}
 * Political parties

{{legend||Military|border=1px solid #AAAAAA}} {{legend||Independent|border=1px solid #AAAAAA}}
 * Other factions


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Endotherm

An endotherm (from Greek ἔνδον endon "within" and θέρμη thermē "heat") is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions instead of relying almost purely on ambient heat. Such internally generated heat is mainly an incidental product of the animal's routine metabolism, but under conditions of excessive cold or low activity an endotherm might apply special mechanisms adapted specifically to heat production. Examples include special-function muscular exertion such as shivering, and uncoupled oxidative metabolism, such as within brown adipose tissue.

Only birds and mammals are extant universally endothermic groups of animals. However, Argentine black and white tegu, leatherback sea turtles, lamnid sharks, tuna and billfishes, cicadas, and winter moths are also endothermic. Unlike mammals and birds, some reptiles, particularly some species of python and tegu, possess seasonal reproductive endothermy in which they are endothermic only during their reproductive season.

In common parlance, endotherms are characterized as "warm-blooded". The opposite of endothermy is ectothermy, although in general, there is no absolute or clear separation between the nature of endotherms and ectotherms.

Origin
Endothermy was thought to have originated towards the end of the Permian Period . One recent study claimed the origin of endothermy within Synapsida (the mammalian lineage) was among Mammaliamorpha, a node calibrated during the Late Triassic period, about 233 million years ago.  Another study instead argued that endothermy only appeared later, during the Middle Jurassic, among crown-group mammals.

Evidence for endothermy has been found in basal synapsids ("pelycosaurs"), pareiasaurs, ichthyosaurs, plesiosaurs, mosasaurs, and basal archosauromorphs. Even the earliest amniotes might have been endotherms.

Generating and conserving heat
Many endotherms have a larger amount of mitochondria per cell than ectotherms. This enables them to generate heat by increasing the rate at which they metabolize fats and sugars. Accordingly, to sustain their higher metabolism, endothermic animals typically require several times as much food as ectothermic animals do, and usually require a more sustained supply of metabolic fuel.

In many endothermic animals, a controlled temporary state of hypothermia conserves energy by permitting the body temperature to drop nearly to ambient levels. Such states may be brief, regular circadian cycles called torpor, or they might occur in much longer, even seasonal, cycles called hibernation. The body temperatures of many small birds (e.g. hummingbirds) and small mammals (e.g. tenrecs) fall dramatically during daily inactivity, such as nightly in diurnal animals or during the day in nocturnal animals, thus reducing the energy cost of maintaining body temperature. Less drastic intermittent reduction in body temperature also occurs in other larger endotherms; for example human metabolism also slows down during sleep, causing a drop in core temperature, commonly of the order of 1 degree Celsius. There may be other variations in temperature, usually smaller, either endogenous or in response to external circumstances or vigorous exertion, and either an increase or a drop.

The resting human body generates about two-thirds of its heat through metabolism in internal organs in the thorax and abdomen, as well as in the brain. The brain generates about 16% of the total heat produced by the body.

Heat loss is a major threat to smaller creatures, as they have a larger ratio of surface area to volume. Small warm-blooded animals have insulation in the form of fur or feathers. Aquatic warm-blooded animals, such as seals, generally have deep layers of blubber under the skin and any pelage (fur) that they might have; both contribute to their insulation. Penguins have both feathers and blubber. Penguin feathers are scale-like and serve both for insulation and streamlining. Endotherms that live in very cold circumstances or conditions predisposing to heat loss, such as polar waters, tend to have specialised structures of blood vessels in their extremities that act as heat exchangers. The veins are adjacent to the arteries full of warm blood. Some of the arterial heat is conducted to the cold blood and recycled back into the trunk. Birds, especially waders, often have very well-developed heat exchange mechanisms in their legs—those in the legs of emperor penguins are part of the adaptations that enable them to spend months on Antarctic winter ice. In response to cold, many warm-blooded animals also reduce blood flow to the skin by vasoconstriction to reduce heat loss. As a result, they blanch (become paler).

Avoiding overheating
In equatorial climates and during temperate summers, overheating (hyperthermia) is as great a threat as cold. In hot conditions, many warm-blooded animals increase heat loss by panting, which cools the animal by increasing water evaporation in the breath, and/or flushing, increasing the blood flow to the skin so the heat will radiate into the environment. Hairless and short-haired mammals, including humans and horses, also sweat, since the evaporation of the water in sweat removes heat. Elephants keep cool by using their huge ears like radiators in automobiles. Their ears are thin and the blood vessels are close to the skin, and flapping their ears to increase the airflow over them causes the blood to cool, which reduces their core body temperature when the blood moves through the rest of the circulatory system.

Pros and cons of an endothermic metabolism
The major advantage of endothermy over ectothermy is decreased vulnerability to fluctuations in external temperature. Regardless of location (and hence external temperature), endothermy maintains a constant core temperature for optimal enzyme activity.

Endotherms control body temperature by internal homeostatic mechanisms. In mammals, two separate homeostatic mechanisms are involved in thermoregulation—one mechanism increases body temperature, while the other decreases it. The presence of two separate mechanisms provides a very high degree of control. This is important because the core temperature of mammals can be controlled to be as close as possible to the optimal temperature for enzyme activity.

The overall rate of an animal's metabolism increases by a factor of about two for every 10 C-change rise in temperature, limited by the need to avoid hyperthermia. Endothermy does not provide greater speed in movement than ectothermy (cold-bloodedness)—ectothermic animals can move as fast as warm-blooded animals of the same size and build when the ectotherm is near or at its optimal temperature, but often cannot maintain high metabolic activity for as long as endotherms. Endothermic/homeothermic animals can be optimally active at more times during the diurnal cycle in places of sharp temperature variations between day and night and during more of the year in places of great seasonal differences of temperature. This is accompanied by the need to expend more energy to maintain the constant internal temperature and a greater food requirement. Endothermy may be important during reproduction, for example, in expanding the thermal range over which a species can reproduce, as embryos are generally intolerant of thermal fluctuations that are easily tolerated by adults. Endothermy may also provide protection against fungal infection. While tens of thousands of fungal species infect insects, only a few hundred target mammals, and often only those with a compromised immune system. A recent study suggests fungi are fundamentally ill-equipped to thrive at mammalian temperatures. The high temperatures afforded by endothermy might have provided an evolutionary advantage.

Ectotherms increase their body temperature mostly through external heat sources such as sunlight energy; therefore, they depend on environmental conditions to reach operational body temperatures. Endothermic animals mostly use internal heat production through metabolic active organs and tissues (liver, kidney, heart, brain, muscle) or specialized heat producing tissues like brown adipose tissue (BAT). In general, endotherms therefore have higher metabolic rates than ectotherms at a given body mass. As a consequence they also need higher food intake rates, which may limit abundance of endotherms more than ectotherms.

Because ectotherms depend on environmental conditions for body temperature regulation, they typically are more sluggish at night and in the morning when they emerge from their shelters to heat up in the first sunlight. Foraging activity is therefore restricted to the daytime (diurnal activity patterns) in most vertebrate ectotherms. In lizards, for instance, only a few species are known to be nocturnal (e.g. many geckos) and they mostly use 'sit and wait' foraging strategies that may not require body temperatures as high as those necessary for active foraging. Endothermic vertebrate species are, therefore, less dependent on the environmental conditions and have developed a high variability (both within and between species) in their diurnal activity patterns.

It is thought that the evolution of endothermia was crucial in the development of eutherian mammalian species diversity in the Mesozoic period. Endothermia gave the early mammals the capacity to be active during nighttime while maintaining small body sizes. Adaptations in photoreception and the loss of UV protection characterizing modern eutherian mammals are understood as adaptations for an originally nocturnal lifestyle, suggesting that the group went through an evolutionary bottleneck (the nocturnal bottleneck hypothesis). This could have avoided predator pressure from diurnal reptiles and dinosaurs, although some predatory dinosaurs, being equally endothermic, might have adapted a nocturnal lifestyle in order to prey on those mammals.

Facultative endothermy
Many insect species are able to maintain a thoracic temperature above the ambient temperature using exercise. These are known as facultative or exercise endotherms. The honey bee, for example, does so by contracting antagonistic flight muscles without moving its wings (see insect thermoregulation). This form of thermogenesis is, however, only efficient above a certain temperature threshold, and below about 9 - 14 °C, the honey bee reverts to ectothermy.

Facultative endothermy can also be seen in multiple snake species that use their metabolic heat to warm their eggs. Python molurus and Morelia spilota are two python species where females surround their eggs and shiver in order to incubate them.

Regional endothermy
Some ectotherms, including several species of fish and reptiles, have been shown to make use of regional endothermy, where muscle activity causes certain parts of the body to remain at higher temperatures than the rest of the body. This allows for better locomotion and use of the senses in cold environments.

Contrast between thermodynamic and biological terminology
Students encounter a source of possible confusion between the terminology of physics and biology. Whereas the thermodynamic terms "exothermic" and "endothermic" respectively refer to processes that give out heat energy and processes that absorb heat energy, in biology the sense is effectively reversed. The metabolic terms "ectotherm" and "endotherm" respectively refer to organisms that rely largely on external heat to achieve a full working temperature, and to organisms that produce heat from within as a major factor in controlling their body temperatures.

title: Endotherm


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List of heads of state of Chad

This is a list of heads of state of Chad since the country gained independence from France in 1960 to the present day.

A total of six people have served as head of state of Chad (not counting two Interim Heads of State). Additionally, one person, Goukouni Oueddei, has served on two non-consecutive occasions.

The current head of state of Chad is Mahamat Déby, since 20 April 2021, when he took power in a military coup following the death of his father, President Idriss Déby. Mahamat Déby was President of the Transitional Military Council, a military junta, from 20 April 2021 until 10 October 2022, when he was sworn is as Transitional President of the Republic following a "national dialogue". On 6 May 2024, Déby won the presidential election and was proclaimed President four days later on 10 May.

Term limits
In 2018, the new Constitution of Chad reinstated two-term limits for the president. It also changed the length of the term from five years to six years. However, in 2023, a constitutional referendum was held which changed the length of the term from six years back to five years and which also lowered the minimum age for the presidency from 40 down to 35.

Titles

 * 1960–1962: Head of State
 * 1962–1975: President of the Republic
 * 1975   : Chairman of the Supreme Military Council
 * 1975–1978: Head of State
 * 1978–1979: President of the Republic
 * 1979   : Chairman of the Provisional Council of State
 * 1979   : President of the Transitional Government of National Unity
 * 1979   : Chairman of the Provisional Administrative Committee
 * 1979–1982: President of the Transitional Government of National Unity
 * 1982   : Chairman of the Command Council of the Armed Forces of the North
 * 1982   : Chairman of the Council of State
 * 1982–1990: President of the Republic
 * 1990   : President of the Patriotic Salvation Movement
 * 1990–1991: President of the Council of State
 * 1991–2021: President of the Republic
 * 2021–2022: President of the Transitional Military Council
 * 2022–2024: Transitional President of the Republic
 * 2024–present: President of the Republic

List of officeholders
{{legend||Chadian Progressive Party (PPT) / National Movement for the Cultural and Social Revolution (MNRCS)|border=1px solid #AAAAAA}} {{legend|Crimson|National Liberation Front of Chad (FROLINAT)–People's Armed Forces (FAP)|border=1px solid #AAAAAA}} {{legend|Salmon|Popular Movement for the Liberation of Chad (MPLT)|border=1px solid #AAAAAA}} {{legend||Armed Forces of the North (FAN) / National Union for Independence and Revolution (UNIR)|border=1px solid #AAAAAA}} {{legend||Patriotic Salvation Movement (MPS)|border=1px solid #AAAAAA}}
 * Political parties

{{legend||Military (Chadian Armed Forces and Chad National Army)|border=1px solid #AAAAAA}}
 * Other factions

{{legend|#E6E6AA|Interim Head of State|border=1px solid #AAAAAA}}
 * Status

Constitutional referendum
 * Symbols

title: List of heads of state of Chad


text:
Anthozoa

Anthozoa is a class of marine invertebrates which includes the sea anemones, stony corals and soft corals. Adult anthozoans are almost all attached to the seabed, while their larvae can disperse as part of the plankton. The basic unit of the adult is the polyp; this consists of a cylindrical column topped by a disc with a central mouth surrounded by tentacles. Sea anemones are mostly solitary, but the majority of corals are colonial, being formed by the budding of new polyps from an original, founding individual. Colonies are strengthened by calcium carbonate and other materials and take various massive, plate-like, bushy or leafy forms.

Anthozoa is included within the phylum Cnidaria, which also includes the jellyfish, box jellies and parasitic Myxozoa and Polypodiozoa. The two main subclasses of Anthozoa are the Hexacorallia, members of which have six-fold symmetry and includes the stony corals, sea anemones, tube anemones and zoanthids; and the Octocorallia, which have eight-fold symmetry and includes the soft corals and gorgonians (sea pens, sea fans and sea whips), and sea pansies. The smaller subclass, Ceriantharia, consists of the tube-dwelling anemones. Some additional species are also included as incertae sedis until their exact taxonomic position can be ascertained.

Anthozoans are carnivores, catching prey with their tentacles. Many species supplement their energy needs by making use of photosynthetic single-celled algae that live within their tissues. These species live in shallow water and many are reef-builders. Other species lack the zooxanthellae and, having no need for well-lit areas, typically live in deep-water locations.

Unlike other members of this phylum, anthozoans do not have a medusa stage in their development. Instead, they release sperm and eggs into the water. After fertilisation, the planula larvae form part of the plankton. When fully developed, the larvae settle on the seabed and attach to the substrate, undergoing metamorphosis into polyps. Some anthozoans can also reproduce asexually through budding or by breaking in pieces.

Diversity
The name "Anthozoa" comes from the Greek words άνθος (ánthos; "flower") and ζώα (zóa; "animals"), hence ανθόζωα (anthozoa) = "flower animals", a reference to the floral appearance of their perennial polyp stage.

Anthozoans are exclusively marine, and include sea anemones, stony corals, soft corals, sea pens, sea fans and sea pansies. Anthozoa is the largest taxon of cnidarians; over six thousand solitary and colonial species have been described. They range in size from small individuals less than half a centimetre across to large colonies a metre or more in diameter. They include species with a wide range of colours and forms that build and enhance reef systems. Although reefs and shallow water environments exhibit a great array of species, there are in fact more species of coral living in deep water than in shallow, and many taxa have shifted during their evolutionary history from shallow to deep water and vice versa.

Phylogeny
Anthozoa is subdivided into three subclasses: Octocorallia, Hexacorallia and Ceriantharia, which form monophyletic groups and generally show differentiating reflections on symmetry of polyp structure for each subclass. The relationships within the subclasses are unresolved.

Historically, the "Ceriantipatharia" was thought to be a separate subclass but, of the two orders it comprised, Antipatharia is now considered part of Hexacorallia and Ceriantharia is now considered an independent subclass. The extant orders are shown to the right.

Hexacorallia includes coral reef builders: the stony corals (Scleractinia), sea anemones (Actiniaria), and zoanthids (Zoantharia). Genetic studies of ribosomal DNA has shown Ceriantharia to be a monophyletic group and the oldest, or basal, order among them.

Classification according to the World Register of Marine Species:
 * subclass Hexacorallia
 * order Actiniaria — sea anemones
 * order Antipatharia — black coral
 * order Corallimorpharia — corallimorphs
 * order Rugosa †
 * order Scleractinia — stony corals
 * order Zoantharia — zoanthids
 * subclass Octocorallia
 * order Alcyonacea — soft corals and gorgonians
 * order Helioporacea — blue corals
 * order Pennatulacea — pennatules, sea feathers, sea pens, sea pansies
 * subclass Ceriantharia — ceriantharians, tube-dwelling anemones
 * order Penicillaria
 * order Spirularia
 * Anthozoa incertae sedis
 * genus Aiptasiodes
 * order Auloporida †
 * genus Sarcinula †

Octocorallia comprises the sea pens (Pennatulacea), soft corals (Alcyonacea), and blue coral (Helioporacea). Sea whips and sea fans, known as gorgonians, are part of Alcyonacea and historically were divided into separate orders.

Ceriantharia comprises the related tube-dwelling anemones. Tube-dwelling anemones or cerianthids look very similar to sea anemones, but belong to an entirely different subclass of anthozoans. They are solitary, living buried in soft sediments. Tube anemones live and can withdraw into tubes, which are made of a fibrous material, which is made from secreted mucus and threads of nematocyst-like organelles, known as ptychocysts.

Anatomy
The basic body form of an anthozoan is the polyp. This consists of a tubular column topped by a flattened area, the oral disc, with a central mouth; a whorl of tentacles surrounds the mouth. In solitary individuals, the base of the polyp is the foot or pedal disc, which adheres to the substrate, while in colonial polyps, the base links to other polyps in the colony.

The mouth leads into a tubular pharynx which descends for some distance into the body before opening into the coelenteron, otherwise known as the gastrovascular cavity, that occupies the interior of the body. Internal tensions pull the mouth into a slit-shape, and the ends of the slit lead into two grooves in the pharynx wall called siphonoglyphs. The coelenteron is subdivided by a number of vertical partitions, known as mesenteries or septa. Some of these extend from the body wall as far as the pharynx and are known as "complete septa" while others do not extend so far and are "incomplete". The septa also attach to the oral and pedal discs.

The body wall consists of an epidermal layer, a jellylike mesogloea layer and an inner gastrodermis; the septa are infoldings of the body wall and consist of a layer of mesogloea sandwiched between two layers of gastrodermis. In some taxa, sphincter muscles in the mesogloea close over the oral disc and act to keep the polyp fully retracted. The tentacles contain extensions of the coelenteron and have sheets of longitudinal muscles in their walls. The oral disc has radial muscles in the epidermis, but most of the muscles in the column are gastrodermal, and include strong retractor muscles beside the septa. The number and arrangement of the septa, as well as the arrangement of these retractor muscles, are important in anthozoan classification.

The tentacles are armed with nematocysts, venom-containing cells which can be fired harpoon-fashion to snare and subdue prey. These need to be replaced after firing, a process that takes about forty-eight hours. Some sea anemones have a circle of acrorhagi outside the tentacles; these long projections are armed with nematocysts and act as weapons. Another form of weapon is the similarly armed acontia (threadlike defensive organs) which can be extruded through apertures in the column wall. Some stony corals employ nematocyst-laden "sweeper tentacles" as a defence against the intrusion of other individuals.

Many anthozoans are colonial and consist of multiple polyps with a common origin joined by living material. The simplest arrangement is where a stolon runs along the substrate in a two dimensional lattice with polyps budding off at intervals. Alternatively, polyps may bud off from a sheet of living tissue, the coenosarc, which joins the polyps and anchors the colony to the substrate. The coenosarc may consist of a thin membrane from which the polyps project, as in most stony corals, or a thick fleshy mass in which the polyps are immersed apart from their oral discs, as in the soft corals.

The skeleton of a stony coral in the order Scleractinia is secreted by the epidermis of the lower part of the polyp; this forms a corallite, a cup-shaped hollow made of calcium carbonate, in which the polyp sits. In colonial corals, following growth of the polyp by budding, new corallites are formed, with the surface of the skeleton being covered by a layer of coenosarc. These colonies adopt a range of massive, branching, leaf-like and encrusting forms. Soft corals in the subclass Octocorallia are also colonial and have a skeleton formed of mesogloeal tissue, often reinforced with calcareous spicules or horny material, and some have rod-like supports internally. Other anthozoans, such as sea anemones, are naked; these rely on a hydrostatic skeleton for support. Some of these species have a sticky epidermis to which sand grains and shell fragments adhere, and zoanthids incorporate these substances into their mesogloea.

Biology
Most anthozoans are opportunistic predators, catching prey which drifts within reach of their tentacles. The prey is secured with the help of sticky mucus, spirocysts (non-venomous harpoon cells) and nematocysts (venomous harpoon cells). The tentacles then bend to push larger prey into the mouth, while smaller, plankton-size prey, is moved by cilia to the tip of the tentacles which are then inserted into the mouth. The mouth can stretch to accommodate large items, and in some species, the lips may extend to help receive the prey. The pharynx then grasps the prey, which is mixed with mucus and slowly swallowed by peristalsis and ciliary action. When the food reaches the coelenteron, extracellular digestion is initiated by the discharge of the septa-based nematocysts and the release of enzymes. The partially digested food fragments are circulated in the coelenteron by cilia, and from here they are taken up by phagocytosis by the gastrodermal cells that line the cavity.

Most anthozoans supplement their predation by incorporating into their tissues certain unicellular, photosynthetic organisms known as zooxanthellae (or zoochlorellae in a few instances); many fulfil the bulk of their nutritional requirements in this way. In this symbiotic relationship, the zooxanthellae benefit by using nitrogenous waste and carbon dioxide produced by the host while the cnidarian gains photosynthetic capability and increased production of calcium carbonate, a substance of great importance to stony corals. The presence of zooxanthellae is not a permanent relationship. Under some circumstances, the symbionts can be expelled, and other species may later move in to take their place. The behaviour of the anthozoan can also be affected, with it choosing to settle in a well lit spot, and competing with its neighbours for light to allow photosynthesis to take place. Where an anthozoan lives in a cave or other dark location, the symbiont may be absent in a species that, in a sunlit location, normally benefits from one. Anthozoans living at depths greater than 50 m are azooxanthellate because there is insufficient light for photosynthesis.

With longitudinal, transverse and radial muscles, polyps are able to elongate and shorten, bend and twist, inflate and deflate, and extend and contract their tentacles. Most polyps extend to feed and contract when disturbed, often invaginating their oral discs and tentacles into the column. Contraction is achieved by pumping fluid out of the coelenteron, and reflation by drawing it in, a task performed by the siphonoglyphs in the pharynx which are lined with beating cilia. Most anthozoans adhere to the substrate with their pedal discs but some are able to detach themselves and move about, while others burrow into the sediment. Movement may be a passive drifting with the currents or in the case of sea anemones, may involve creeping along a surface on their base.

Gas exchange and excretion is accomplished by diffusion through the tentacles and internal and external body wall, aided by the movement of fluid being wafted along these surfaces by cilia. The sensory system consists of simple nerve nets in the gastrodermis and epidermis, but there are no specialised sense organs.

Anthozoans exhibit great powers of regeneration; lost parts swiftly regrow and the sea anemone Aiptasia pallida can be vivisected in the laboratory and then returned to the aquarium where it will heal. They are capable of a variety of asexual means of reproduction including fragmentation, longitudinal and transverse fission and budding. Sea anemones for example can crawl across a surface leaving behind them detached pieces of the pedal disc which develop into new clonal individuals. Anthopleura species divide longitudinally, pulling themselves apart, resulting in groups of individuals with identical colouring and patterning. Transverse fission is less common, but occurs in Anthopleura stellula and Gonactinia prolifera, with a rudimentary band of tentacles appearing on the column before the sea anemone tears itself apart. Zoanthids are capable of budding off new individuals.

Most anthozoans are unisexual but some stony corals are hermaphrodite. The germ cells originate in the endoderm and move to the gastrodermis where they differentiate. When mature, they are liberated into the coelenteron and thence to the open sea, with fertilisation being external. To make fertilisation more likely, corals emit vast numbers of gametes, and many species synchronise their release in relation to the time of day and the phase of the moon.

The zygote develops into a planula larva which swims by means of cilia and forms part of the plankton for a while before settling on the seabed and metamorphosing into a juvenile polyp. Some planulae contain yolky material and others incorporate zooxanthellae, and these adaptations enable these larvae to sustain themselves and disperse more widely. The planulae of the stony coral Pocillopora damicornis, for example, have lipid-rich yolks and remain viable for as long as 100 days before needing to settle.

Ecology
Coral reefs are some of the most biodiverse habitats on earth, supporting large numbers of species of corals, fish, molluscs, worms, arthropods, starfish, sea urchins, other invertebrates and algae. Because of the photosynthetic requirements of the corals, they are found in shallow waters, and many of these fringe land masses. With a three-dimensional structure, coral reefs are very productive ecosystems; they provide food for their inhabitants, hiding places of various sizes to suit many organisms, perching places, barriers to large predators and solid structures on which to grow. They are used as breeding grounds and as nurseries by many species of pelagic fish, and they influence the productivity of the ocean for miles around. Anthozoans prey on animals smaller than they are and are themselves eaten by such animals as fish, crabs, barnacles, snails and starfish. Their habitats are easily disturbed by outside factors which unbalance the ecosystem. In 1989, the invasive crown-of-thorns starfish (Acanthaster planci) caused havoc in American Samoa, killing 90% of the corals in the reefs.

Corals that grow on reefs are called hermatypic, with those growing elsewhere are known as ahermatypic. Most of the latter are azooxanthellate and live in both shallow and deep sea habitats. In the deep sea they share the ecosystem with soft corals, polychaete worms, other worms, crustaceans, molluscs and sponges. In the Atlantic Ocean, the cold-water coral Lophelia pertusa forms extensive deep-water reefs which support many other species.

Other fauna, such as hydrozoa, bryozoa and brittle stars, often dwell among the branches of gorgonian and coral colonies. The pygmy seahorse not only makes certain species of gorgonians its home, but closely resembles its host and is thus well camouflaged. Some organisms have an obligate relationship with their host species. The mollusc Simnialena marferula is only found on the sea whip Leptogorgia virgulata, is coloured like it and has sequestered its defensive chemicals, and the nudibranch Tritonia wellsi is another obligate symbiont, its feathery gills resembling the tentacles of the polyps.

A number of sea anemone species are commensal with other organisms. Certain crabs and hermit crabs seek out sea anemones and place them on their shells for protection, and fish, shrimps and crabs live among the anemone's tentacles, gaining protection by being in close proximity to the stinging cells. Some amphipods live inside the coelenteron of the sea anemone. Despite their venomous cells, sea anemones are eaten by fish, starfish, worms, sea spiders and molluscs. The sea slug Aeolidia papillosa feeds on the aggregating anemone (Anthopleura elegantissima), accumulating the nematocysts for its own protection.

Paleontology
Several extinct orders of corals from the Paleozoic era (~540–252 million years ago) are thought to be close to the ancestors of modern Scleractinia:

 * Numidiaphyllida †
 * Kilbuchophyllida †
 * Heterocorallia †
 * Rugosa †
 * Heliolitida †
 * Tabulata †
 * Cothoniida †
 * Tabuloconida †

These are all corals and correspond to the fossil record time line. With readily-preserved hard calcareous skeletons, they comprise the majority of Anthozoan fossils.

Interactions with humans
Coral reefs and shallow marine environments are threatened, not only by natural events and increased sea temperatures, but also by such man-made problems as pollution, sedimentation and destructive fishing practices. Pollution may be the result of run-off from the land of sewage, agricultural products, fuel or chemicals. These may directly kill or injure marine life, or may encourage the growth of algae that smother native species, or form algal blooms with wide-ranging effects. Oil spills at sea can contaminate reefs, and also affect the eggs and larva of marine life drifting near the surface.

Corals are collected for the aquarium trade, and this may be done with little care for the long-term survival of the reef. Fishing among reefs is difficult and trawling does much mechanical damage. In some parts of the world explosives are used to dislodge fish from reefs, and cyanide may be used for the same purpose; both practices not only kill reef inhabitants indiscriminately but also kill or damage the corals, sometimes stressing them so much that they expel their zooxanthellae and become bleached.

Deep water coral habitats are also threatened by human activities, particularly by indiscriminate trawling. These ecosystems have been little studied, but in the perpetual darkness and cold temperatures, animals grow and mature slowly and there are relatively fewer fish worth catching than in the sunlit waters above. To what extent deep-water coral reefs provide a safe nursery area for juvenile fish has not been established, but they may be important for many cold-water species.

title: Anthozoa