Amphisbaenia /æmfɪsˈbiːniə/ (called amphisbaenians or worm lizards) is a group of usually legless squamates, comprising over 200 extant species. Amphisbaenians are characterized by their long bodies, the reduction or loss of the limbs, and rudimentary eyes. As many species have a pink body and scales arranged in rings, they have a superficial resemblance to earthworms. While the genus Bipes retains forelimbs, all other genera are limbless. Although superficially similar to other limbless vertebrates including the snakes, legless lizards, and blind lizards, recent phylogenetic studies suggest that they are most closely related to wall lizards of the family Lacertidae. Amphisbaenians are widely distributed, occurring in North America, Europe, Africa, South America, Western Asia and the Caribbean. Most species are less than 6 inches (15 cm) long. (Full article...)

A caiman (/ˈkeɪmən/; also cayman as a variant spelling from Taíno kaiman) is an alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within the Alligatoridae family, the other being alligators. Caimans inhabit Mexico and Central & South America from marshes and swamps to mangrove rivers and lakes. They have scaly skin and live a fairly nocturnal existence. They are relatively small-sized crocodilians with an average maximum weight of 6 to 40 kg (13 to 88 lb) depending on species, with the exception of the black caiman (Melanosuchus niger), which can grow more than 4 m (13 ft) in length and weigh in excess of 1,000 kg (2,200 Ib). The black caiman is the largest caiman species in the world and is found in the slow-moving rivers and lakes that surround the Amazon basin. The smallest species is the Cuvier's dwarf caiman (Paleosuchus palpebrosus), which grows to 1.2 to 1.5 m (3.9 to 4.9 ft) long. There are six different species of caiman found throughout the watery jungle habitats of Central and Southern America. The average length for most of the other caiman species is about 2 to 2.5 m (6.6 to 8.2 ft) long. (Full article...)

Tuatara (Sphenodon punctatus) are reptiles endemic to New Zealand. Despite their close resemblance to lizards, they are part of a distinct lineage, the order Rhynchocephalia. The name tuatara is derived from the Māori language and means "peaks on the back". (Full article...)

The gharial (Gavialis gangeticus), also known as gavial or fish-eating crocodile, is a crocodilian in the family Gavialidae and among the longest of all living crocodilians. Mature females are 2.6 to 4.5 m (8 ft 6 in to 14 ft 9 in) long, and males 3 to 6 m (9 ft 10 in to 19 ft 8 in). Adult males have a distinct boss at the end of the snout, which resembles an earthenware pot known as a ghara, hence the name "gharial". The gharial is well adapted to catching fish because of its long, narrow snout and 110 sharp, interlocking teeth. (Full article...)

Tortoises (/ˈtɔːr.təs.ɪz/) are reptiles of the family Testudinidae of the order Testudines (Latin for "tortoise"). Like other turtles, tortoises have a shell to protect from predation and other threats. The shell in tortoises is generally hard, and like other members of the suborder Cryptodira, they retract their necks and heads directly backward into the shell to protect them. (Full article...)

Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia, and some lizards are more closely related to these two excluded groups than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3-meter-long Komodo dragon. (Full article...)

Crocodiles (family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to include all extant members of the order Crocodilia, which includes the alligators and caimans (family Alligatoridae), the gharial and false gharial (family Gavialidae) among other extinct taxa. (Full article...)

Turtles are reptiles of the order Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked turtles), which differ in the way the head retracts. There are 360 living and recently extinct species of turtles, including land-dwelling tortoises and freshwater terrapins. They are found on most continents, some islands and, in the case of sea turtles, much of the ocean. Like other amniotes (reptiles, birds, and mammals) they breathe air and do not lay eggs underwater, although many species live in or around water. (Full article...)

Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes (/sɜːrˈpɛntiːz/). Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more joints than their lizard ancestors, enabling them to swallow prey much larger than their heads (cranial kinesis). To accommodate their narrow bodies, snakes' paired organs (such as kidneys) appear one in front of the other instead of side by side, and most have only one functional lung. Some species retain a pelvic girdle with a pair of vestigial claws on either side of the cloaca. Lizards have independently evolved elongate bodies without limbs or with greatly reduced limbs at least twenty-five times via convergent evolution, leading to many lineages of legless lizards. These resemble snakes, but several common groups of legless lizards have eyelids and external ears, which snakes lack, although this rule is not universal (see Amphisbaenia, Dibamidae, and Pygopodidae). (Full article...)

An alligator, or colloquially gator, is a large reptile in the Crocodilia order in the genus Alligator of the family Alligatoridae. The two extant species are the American alligator (A. mississippiensis) and the Chinese alligator (A. sinensis). Additionally, several extinct species of alligator are known from fossil remains. Alligators first appeared during the Oligocene epoch about 37 million years ago. (Full article...)

The gharial (Gavialis gangeticus), also known as gavial or fish-eating crocodile, is a crocodilian in the family Gavialidae and among the longest of all living crocodilians. Mature females are 2.6 to 4.5 m (8 ft 6 in to 14 ft 9 in) long, and males 3 to 6 m (9 ft 10 in to 19 ft 8 in). Adult males have a distinct boss at the end of the snout, which resembles an earthenware pot known as a ghara, hence the name "gharial". The gharial is well adapted to catching fish because of its long, narrow snout and 110 sharp, interlocking teeth.

The gharial probably evolved in the northern Indian subcontinent. Fossil gharial remains were excavated in Pliocene deposits in the Sivalik Hills and the Narmada River valley. It currently inhabits rivers in the plains of the northern part of the Indian subcontinent. It is the most thoroughly aquatic crocodilian, and leaves the water only for basking and building nests on moist sandbanks. Adults mate at the end of the cold season. Females congregate in spring to dig nests, in which they lay 20–95 eggs. They guard the nests and the young, which hatch before the onset of the monsoon. The hatchlings stay and forage in shallow water during their first year, but move to sites with deeper water as they grow. (Full article...)

The Chinese alligator (Alligator sinensis; simplified Chinese: 鼍; traditional Chinese: 鼉; pinyin: tuó), also known as the Yangtze alligator (simplified Chinese: 扬子鳄; traditional Chinese: 揚子鱷; pinyin: yángzǐ'è), China alligator, or historically the muddy dragon, is a crocodilian endemic to China. It and the American alligator (A. mississippiensis) are the only living species in the genus Alligator of the family Alligatoridae. Dark gray or black in color with a fully armored body, the Chinese alligator grows to 1.5–2.1 metres (5–7 ft) in length and weighs 36–45 kilograms (80–100 lb) as an adult. It brumates in burrows in winter and is nocturnal in summer. Mating occurs in early summer, with females most commonly producing 20–30 eggs, which are smaller than those of any other crocodilian. The species is an opportunistic feeder, primarily eating fish and invertebrates. A vocal species, adults bellow during the mating season and young vocalize to communicate with their parents and other juveniles. Captive specimens have reached age 70, and wild specimens can live past 50.

Living in bodies of fresh water, the Chinese alligator's range is restricted to six regions in the province of Anhui, as well as possibly the provinces of Jiangsu and Zhejiang. Originally living as far away from its current range as Japan, the species previously had a wide range and population, but beginning in 5000 BC, multiple threats, such as habitat destruction, caused the species' population and range to decline. The population in the wild was about 1,000 in the 1970s, decreased to below 130 in 2001, and grew after 2003, with its population being about 300 as of 2017. Listed as critically endangered by the International Union for Conservation of Nature, multiple conservation actions have been taking place for this species. (Full article...)

The American crocodile (Crocodylus acutus) is a species of crocodilian found in the Neotropics. It is the most widespread of the four extant species of crocodiles from the Americas, with populations present from South Florida and the coasts of Mexico to as far south as Peru and Venezuela.

The habitat of the American crocodile consists largely of coastal areas. It is also found in river systems, but tends to prefer salinity, resulting in the species congregating in brackish lakes, mangrove swamps, lagoons, cays, and small islands. Other crocodiles also have tolerance to saltwater due to salt glands underneath the tongue, but the American crocodile is the only species other than the saltwater crocodile to commonly live and thrive in saltwater. They can be found on beaches and small island formations without any freshwater source, such as many cays and islets across the Caribbean. They are also found in hypersaline lakes; one of the largest known populations inhabits Lago Enriquillo in the Dominican Republic. (Full article...)

The Nile crocodile (Crocodylus niloticus) is a large crocodilian native to freshwater habitats in Africa, where it is present in 26 countries. It is widely distributed in sub-Saharan Africa, occurring mostly in the eastern, southern, and central regions of the continent, and lives in different types of aquatic environments such as lakes, rivers, swamps, and marshlands. Although capable of living in saline environments, this species is rarely found in saltwater, but occasionally inhabits deltas and brackish lakes. The range of this species once stretched northward throughout the Nile River, as far north as the Nile Delta. Generally, the adult male Nile crocodile is between 3.5 and 5 m (11 ft 6 in and 16 ft 5 in) in length and weighs 225 to 750 kg (500 to 1,650 lb). However, specimens exceeding 6.1 m (20 ft) in length and 1,000 kg (2,200 lb) in weight have been recorded. It is the largest freshwater predator in Africa, and may be considered the second-largest extant reptile in the world, after the saltwater crocodile (Crocodylus porosus). Size is sexually dimorphic, with females usually about 30% smaller than males. The crocodile has thick, scaly, heavily armoured skin.

Nile crocodiles are opportunistic apex predators; a very aggressive crocodile, they are capable of taking almost any animal within their range. They are generalists, taking a variety of prey. Their diet consists mostly of different species of fish, reptiles, birds, and mammals. They are ambush predators that can wait for hours, days, and even weeks for the suitable moment to attack. They are agile predators and wait for the opportunity for a prey item to come well within attack range. Even swift prey are not immune to attack. Like other crocodiles, Nile crocodiles have a powerful bite that is unique among all animals, and sharp, conical teeth that sink into flesh, allowing a grip that is almost impossible to loosen. They can apply high force for extended periods of time, a great advantage for holding down large prey underwater to drown. (Full article...)

Cuvier's dwarf caiman (Paleosuchus palpebrosus) is a small crocodilian in the alligator family from northern and central South America. It is found in Brazil, Bolivia, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname, Trinidad and Venezuela. It lives in riverine forests, flooded forests near lakes, and near fast-flowing rivers and streams. It can traverse dry land to reach temporary pools and tolerates colder water than other species of caimans. Other common names for this species include the musky caiman, the dwarf caiman, Cuvier's caiman, and the smooth-fronted caiman (the latter name is also used for P. trigonatus). It is sometimes kept in captivity as a pet and may be referred to as the wedge-head caiman by the pet trade community.

Cuvier's dwarf caiman was first described by the French zoologist Georges Cuvier in 1807 and is one of only two species in the genus Paleosuchus, the other species being P. trigonatus. Their closest relatives are the other caimans in the subfamily Caimaninae. With a total length averaging 1.4 m (4.6 ft) for males and up to 1.2 m (3.9 ft) for females, Cuvier's dwarf caiman is not only the smallest extant species in the alligator and caiman family, but also the smallest of all crocodilians. An adult weighs around 5 to 7 kg (11 to 15 lb). Its lack of size is partly made up for by its strong body armor, provided by the bony bases to its dermal scales, which provides protection against predators. Juvenile dwarf caimans mainly feed on invertebrates, but also small fish and frogs, while adults eat larger fish, amphibians, and invertebrates, such as large molluscs. This caiman sometimes uses a burrow as shelter during the day and in the Pantanal may aestivate in the burrow to stay cool in the dry season. The female buries her eggs on a mounded nest and these take about 3 months to hatch. She helps the hatchlings to escape from the nest and provides some parental care for the first few weeks of their lives. This caiman has a wide range and large total population and the IUCN lists its conservation status as being of least concern. (Full article...)

The dwarf crocodile (Osteolaemus tetraspis), also known as the African dwarf crocodile, broad-snouted crocodile (a name more often used for the Asian mugger crocodile) or bony crocodile, is an African crocodile that is also the smallest extant (living) species of crocodile. (Full article...)

The yacare caiman (Caiman yacare), also known commonly as the jacare caiman, Paraguayan caiman, piranha caiman, red caiman, and southern spectacled caiman, is a species of caiman, a crocodilian in the family Alligatoridae. The species is endemic to Argentina, Bolivia, Brazil, and Paraguay. Brown in color and covered with dark blotches, males grow to a total length (including tail) of 2–3 m (6 ft 7 in – 9 ft 10 in) and weigh around 40–50 kg (88–110 lb); while females grow to 1.4 m (4 ft 7 in) long and about 15–20 kg (33–44 lb). Typical habitats of this caiman include lakes, rivers, and wetlands. Its diet primarily consists of aquatic animals, such as snails, and occasionally land vertebrates. Mating occurs in the rainy season and eggs hatch in March, with young fending for themselves as soon as they hatch. The yacare caiman was hunted heavily for its skin to use for leather in the 1980s, which caused its population to decrease significantly. However, trading restrictions placed since have caused its population to increase. Its population in the Pantanal is about 10 million, and it is listed as least concern on the IUCN Red List. (Full article...)

The Philippine crocodile (Crocodylus mindorensis), also known as the Mindoro crocodile, the Philippine freshwater crocodile, the bukarot in Ilocano, and more generally as a buwaya in most Filipino lowland cultures, is one of two species of crocodiles found in the Philippines; the other is the larger saltwater crocodile (Crocodylus porosus). The Philippine crocodile, the species endemic only to the country, went from data deficient to critically endangered in 2008 from exploitation and unsustainable fishing methods, such as dynamite fishing. Conservation methods are being taken by the Dutch/Filipino Mabuwaya foundation, the Crocodile Conservation Society and the Zoological Institute of HerpaWorld in Mindoro island. It is strictly prohibited to kill a crocodile in the country, and it is punishable by law. (Full article...)

The black caiman (Melanosuchus niger) is a crocodilian reptile endemic to South America. With a maximum length of around 5 to 6 m (16 to 20 ft) and a mass of over 450 kg (1,000 lb), it is the largest living species of the family Alligatoridae, and the third-largest in the Neotropical realm. True to its common and scientific names, the black caiman has a dark greenish-black coloration as an adult. In some individuals, the pigmentation can appear almost jet-black. It has grey to brown banding on the lower jaw; juveniles have a more vibrant coloration compared to adults, with prominent white-pale yellow banding on the flanks that remains present well into adulthood (more than most other species). The banding on young animals helps with camouflage by breaking up their body outline, on land or in water, in an effort to avoid predation. The morphology is quite different from other caimans but the bony ridge that occurs in other caimans is present. The head is large and heavy, an advantage in catching larger prey. Like all crocodilians, caimans are long, squat creatures, with big jaws, long tails and short legs. They have thick, scaled skin, and their eyes and noses are located on the tops of their heads. This enables them to see and breathe while the rest of their bodies are underwater.

A carnivorous animal, the black caiman lives along freshwater habitats, including slow-moving rivers, lakes and seasonally flooded savannas, where it preys upon a variety of fish, reptiles, birds, and mammals. Being an apex predator and potentially a keystone species, it is generalist, capable of taking most animals within its range, and might have played a critical role in maintaining structure of the ecosystem. Although merely few specific ecological studies have been conducted, it is observed that this species has its own niche which allows coexistence with other competitors. (Full article...)

The saltwater crocodile (Crocodylus porosus) is a crocodilian native to saltwater habitats, brackish wetlands and freshwater rivers from India's east coast across Southeast Asia and the Sundaic region to northern Australia and Micronesia. It has been listed as Least Concern on the IUCN Red List since 1996. It was hunted for its skin throughout its range up to the 1970s, and is threatened by illegal killing and habitat loss. It is regarded as dangerous to humans.

The saltwater crocodile is the largest living reptile. Males can grow up to a length of 6 m (20 ft), rarely exceeding 6.3 m (21 ft), and a weight of 1,000–1,500 kg (2,200–3,300 lb). Females are much smaller and rarely surpass 3 m (10 ft). It is also called the estuarine crocodile, Indo-Pacific crocodile, marine crocodile, sea crocodile, and, informally, the saltie. A large and opportunistic hypercarnivorous apex predator, they ambush most of their prey and then drown or swallow it whole. They will prey on almost any animal that enters their territory, including other predators such as sharks, varieties of freshwater and saltwater fish including pelagic species, invertebrates such as crustaceans, various amphibians, reptiles, birds, and mammals, including humans. (Full article...)

Mecistops is a genus of crocodiles, the slender-snouted crocodiles, native to sub-Saharan Africa. (Full article...)

The smooth-fronted caiman (Paleosuchus trigonatus), also known as Schneider's dwarf caiman or Schneider's smooth-fronted caiman, is a crocodilian from South America, where it is native to the Amazon and Orinoco Basins. It is the second-smallest species of the family Alligatoridae, the smallest being Cuvier's dwarf caiman, also from tropical South America and in the same genus. An adult typically grows to around 1.2 to 1.6 m (3.9 to 5.2 ft) in length and weighs between 9 and 20 kg (20 and 44 lb). Exceptionally large males can reach as much as 2.3 m (7.5 ft) in length and 36 kg (79 lb) in weight. (Full article...)

The West African crocodile, desert crocodile, or sacred crocodile (Crocodylus suchus) is a species of crocodile related to — and often confused with — the larger and more aggressive Nile crocodile (C. niloticus). (Full article...)

The Siamese crocodile (Crocodylus siamensis) is a medium-sized freshwater crocodile native to Indonesia (Borneo and possibly Java), Brunei, East Malaysia, Laos, Cambodia, Myanmar, Thailand and Vietnam. The species is critically endangered and already extirpated from many regions. Its other common names include Siamese freshwater crocodile, Singapore small-grain, and soft-belly. (Full article...)

The broad-snouted caiman (Caiman latirostris) is a crocodilian in the family Alligatoridae found in eastern and central South America, including southeastern Brazil, northern Argentina, Uruguay, Paraguay, and Bolivia. It is found mostly in freshwater marshes, swamps, and mangroves, usually in still or very slow-moving waters. It will often use man-made cow ponds. (Full article...)

The American alligator (Alligator mississippiensis), sometimes referred to colloquially as a gator or common alligator, is a large crocodilian reptile native to the Southeastern United States. It is one of the two extant species in the genus Alligator, and is larger than the only other living alligator species, the Chinese alligator.

Adult male American alligators measure 3.4 to 4.6 m (11.2 to 15.1 ft) in length, and can weigh up to 500 kg (1,100 lb), with unverified sizes of up to 5.84 m (19.2 ft) and weights of 1,000 kg (2,200 lb) making it the second largest member of the family Alligatoridae, after the black caiman. Females are smaller, measuring 2.6 to 3 m (8.5 to 9.8 ft) in length. The American alligator inhabits subtropical and tropical freshwater wetlands, such as marshes and cypress swamps, from southern Texas to North Carolina. It is distinguished from the sympatric American crocodile by its broader snout, with overlapping jaws and darker coloration, and is less tolerant of saltwater but more tolerant of cooler climates than the American crocodile, which is found only in tropical and warm subtropical climates. (Full article...)

The mugger crocodile (Crocodylus palustris) is a medium-sized broad-snouted crocodile, also known as mugger and marsh crocodile. It is native to freshwater habitats from southern Iran to the Indian subcontinent, where it inhabits marshes, lakes, rivers and artificial ponds. It rarely reaches a body length of 5 m (16 ft 5 in) and is a powerful swimmer, but also walks on land in search of suitable waterbodies during the hot season. Both young and adult mugger crocodiles dig burrows to which they retreat when the ambient temperature drops below 5 °C (41 °F) or exceeds 38 °C (100 °F). Females dig holes in the sand as nesting sites and lay up to 46 eggs during the dry season. The sex of hatchlings depends on temperature during incubation. Both parents protect the young for up to one year. They feed on insects, and adults prey on fish, reptiles, birds and mammals.

The mugger crocodile evolved at least 4.19 million years ago and has been a symbol for the fructifying and destructive powers of the rivers since the Vedic period. It was first scientifically described in 1831 and is protected by law in Iran, India and Sri Lanka. Since 1982, it has been listed as Vulnerable on the IUCN Red List. Outside protected areas, it is threatened by conversion of natural habitats, gets entangled in fishing nets and is killed in human–wildlife conflict situations and in traffic accidents. (Full article...)

The spectacled caiman (Caiman crocodilus), also known as the white caiman, common caiman, and speckled caiman, is a crocodilian in the family Alligatoridae. It is brownish-, greenish-, or yellowish-gray colored and has a spectacle-like ridge between its eyes, which is where its common name come from. It grows to a length of 1.4–2.5 m (4 ft 7 in – 8 ft 2 in) and a weight of 7–40 kg (15–88 lb), with males being both longer and heavier than females. Its diet varies seasonally, commonly consisting of crabs, fish, small mammals, amphibians and snails. Breeding occurs from May to August and 14–40 eggs are laid in July and August. This crocodilian has a large range and population; it is native to much of Latin America, and has been introduced to the United States, Cuba, and Puerto Rico. (Full article...)

The New Guinea crocodile (Crocodylus novaeguineae) is a small species of crocodile found on the island of New Guinea north of the mountain ridge that runs along the centre of the island. The population found south of the mountain ridge, formerly considered a genetically distinct population, is now considered a distinct species, Hall's New Guinea crocodile (C. halli). In the past it included the Philippine crocodile, C. n. mindorensis, as a subspecies, but today they are regarded as separate species. The habitat of the New Guinea crocodile is mostly freshwater swamps and lakes. It is most active at night when it feeds on fish and a range of other small animals. A female crocodile lays a clutch of eggs in a nest composed of vegetation and she lies up nearby to guard the nest. There is some degree of parental care for newly hatched juveniles. This crocodile was over-hunted for its valuable skin in the mid 20th century, but conservation measures have since been put in place, it is reared in ranches and the International Union for Conservation of Nature (IUCN) lists it as being of "Least Concern". (Full article...)

The freshwater crocodile (Crocodylus johnstoni), also known as the Australian freshwater crocodile, Johnstone's crocodile or the freshie, is a species of crocodile endemic to the northern regions of Australia. Unlike their much larger Australian relative, the saltwater crocodile, freshwater crocodiles are not known as man-eaters, although they bite in self-defence, and brief, nonfatal attacks have occurred, apparently the result of mistaken identity. (Full article...)

The Cuban crocodile (Crocodylus rhombifer) is a small-medium species of crocodile endemic to Cuba. Typical length is 2.1–2.3 m (6.9–7.5 ft) and typical weight 70–80 kg (150–180 lb). Large males can reach as much as 3.5 m (11 ft) in length and weigh more than 215 kg (474 lb). Despite its smaller size, it is a highly aggressive animal (one of the most territorial of all crocodilians), and potentially dangerous to humans.

The Cuban crocodile is of interest to biologists, for its unique physical and behavioral traits. Long- and strong-legged, it is the most terrestrial of extant crocodiles. Its preferred habitat comprises freshwater and brackish water environments, such as mangrove swamps, coastal lagoons, estuaries, marshes, floodplains, and river deltas. There, the adults feed on fish, turtles and small mammals, while the young eat invertebrates and smaller fish. Mating occurs between May and July. Captive animals have displayed cooperative hunting behavior, and can be taught tricks, suggesting intelligence. (Full article...)

Morelet's crocodile (Crocodylus moreletii), also known as the Mexican crocodile or Belize crocodile, is a modest-sized crocodilian found only in fresh waters of the Atlantic regions of Mexico, Belize and Guatemala. It usually grows to about 3 metres (10 ft) in length. It is a Least Concern species.
The species has a fossil record in Guatemala. (Full article...)

The Orinoco crocodile (Crocodylus intermedius) is a critically endangered crocodile. Its population is very small, and they can only be found in the Orinoco river basin in Venezuela and Colombia. Extensively hunted for their skins in the 19th and 20th centuries, it is one of the most endangered species of crocodiles. It is a very large species of crocodilian; males have been reported up to 6.8 m (22 ft 4 in) in the past, weighing over 900 kg (2,000 lb), but such sizes do not exist today, 5.2 m (17 ft 1 in) being a more widely accepted maximum size. A large male today may attain 4.2 m (13 ft 9 in) in length and can weigh up to 450 kg (1,000 lb), while females are substantially smaller with the largest likely to weigh around 225 kg (496 lb). Sexual dimorphism is not as profound as in other crocodilian species. The coloration is light even in adults.

The biology of the Orinoco crocodile is poorly documented in the wild, mostly due to its small population. It is thought to have a more piscivorous diet with an opportunistic nature, resulting in generalist predatory behaviour. The Orinoco crocodile is an apex predator, and will take the opportunity to prey on a variety of birds, mammals, and reptiles, including caimans on occasion. The prey base is mostly made up of large predatory fish, challenging the general view by locals complaining about crocodiles hunting local fish to very low numbers. Despite its large size, the Orinoco crocodile rarely poses a threat to humans, despite several reports. Reproduction takes place in the dry season when the water level is lower. Orinoco crocodiles are hole nesters, just like the related Nile, freshwater, and saltwater crocodiles, and they dig holes in the sand to lay their eggs. The females guard the nests and young for several years. (Full article...)

Crotalus helleri or Crotalus oreganus helleri, known as the Southern Pacific rattlesnake, black diamond rattlesnake, and by other names, is a pit viper species or subspecies found in southwestern California and south into Baja California, Mexico, that is known for its regional variety of dangerous venom types. It is sometimes considered a subspecies of Crotalus oreganus. (Full article...)

The snouted cobra (Naja annulifera), also called the banded Egyptian cobra, is a highly venomous species of cobra found in Southern Africa. (Full article...)

Deinagkistrodon is a monotypic genus created for the venomous pit viper species, Deinagkistrodon acutus, which is endemic to Southeast Asia. No subspecies are currently recognized. (Full article...)

Dasypeltis is a genus of colubrid snakes. It is one of only two taxonomic groups of snakes known to have adapted to feed exclusively on eggs (the other being the genus Elachistodon). Dasypeltis are non-venomous and found throughout the continent of Africa, primarily in forested or wooded habitats that are also home to numerous species of birds. (Full article...)

The greater black krait (Bungarus niger) or black krait, is a species of krait, a venomous snake in the genus Bungarus of the family Elapidae. The species is endemic to South Asia. (Full article...)

Craspedocephalus gramineus, known as the bamboo pit viper, Indian green pit viper, or common green pit viper, is a venomous pit viper species found in the southern and north eastern parts of India. No subspecies are currently recognized. (Full article...)

The eastern racer, or North American racer (Coluber constrictor), is a species of nonvenomous snake in the family Colubridae. The species is endemic to North America and Central America. Eleven subspecies, including the nominotypical subspecies, are recognized, which as a group are commonly referred to as the eastern racers. The species is monotypic in the genus Coluber. (Full article...)

The Persian ratsnake (Zamenis persicus) is a species of medium-sized nonvenomous snake in the family Colubridae. The species is endemic to Western Asia. (Full article...)

The rubber boa (Charina bottae) is a species of snake in the family Boidae and is native to western North America. It is sometimes known as the coastal rubber boa or the northern rubber boa and is not to be confused with the southern rubber boa (Charina umbratica). (Full article...)

There is a genus of snake named black-headed snake: (Full article...)

Coelognathus flavolineatus, the black copper rat snake or yellow striped snake, is a species of colubrid snake found in Southeast Asia. This species was previously recognized in the genus Elaphe. (Full article...)

The tiger snake (Notechis scutatus) is a large and highly venomous snake of southern Australia, including its coastal islands and Tasmania. These snakes are often observed and locally well known by their banding, black and yellow like a tiger, although the species can be highly variable in coloration and patterning. All populations are classified within the genus Notechis (Elapidae). Their diverse characteristics have been classified either as distinct species or by subspecies and regional variation. (Full article...)

Vipera aspis is a viper species found in southwestern Europe.
Its common names include asp, asp viper, European asp, and aspic viper, among others. Like all other vipers, it is venomous. Bites from this species can be more severe than from the European adder, V. berus; not only can they be very painful, but approximately 4% of all untreated bites are fatal. The specific epithet, aspis, is a Greek word that means "viper." Five subspecies are currently recognized, including the nominate subspecies described here. (Full article...)

Rhinophis saffragamus, the large shieldtail snake, is a species of snake in the family Uropeltidae, which is endemic to the island of Sri Lanka. No subspecies are currently recognized. (Full article...)

Trimeresurus albolabris, the white-lipped pit viper or white-lipped tree viper, is a venomous pit viper species endemic to Southeast Asia. (Full article...)

Protobothrops cornutus, commonly known as the horned pit viper or Fan-Si-Pan horned pitviper, is a venomous pit viper species found in northern and central Vietnam and in southern China (Guangdong). No subspecies are currently recognized. (Full article...)

The speckled kingsnake (Lampropeltis holbrooki) is a nonvenomous species of kingsnake. It is endemic to the United States. (Full article...)

Fox snake or foxsnake is the common name given to some North American rat snakes of the genus Pantherophis. It is generally agreed that there are two such species, but three candidate species names have arisen for them:

• Pantherophis gloydi (eastern fox snake), originally described by Conant in 1940, merged with P. vulpinus in 2011
• Pantherophis vulpinus (foxsnake or western fox snake or eastern fox snake), originally described by Baird and Girard in 1853
• Pantherophis ramspotti (western fox snake), originally described by Crother, White, Savage, Eckstut, Graham and Gardner in 2011

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The Japanese keelback (Hebius vibakari) is a species of colubrid snake, which is endemic to Asia. (Full article...)

The Aesculapian snake /ˌɛskjəˈleɪpiən/ (now Zamenis longissimus, previously Elaphe longissima), is a species of nonvenomous snake native to Europe, a member of the Colubrinae subfamily of the family Colubridae. Growing up to 2 metres (6.6 ft) in length, it is among the largest European snakes, similar in size to the four-lined snake (Elaphe quatuorlineata) and the Montpellier snake (Malpolon monspessulanus). The Aesculapian snake has been of cultural and historical significance for its role in ancient Greek, Roman and Illyrian mythology and derived symbolism. (Full article...)

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The gray-banded kingsnake (Lampropeltis alterna), sometimes referred to as the alterna or the Davis Mountain king snake, is a species of nonvenomous snake in the family Colubridae. The species is endemic to the southwestern United States and adjacent Mexico. Some sources list two distinct subspecies of Lampropeltis alterna, as L. a. alterna and L. a. blairi differentiated by patterning and locale, but research has shown them to be color morphs of the same species. (Full article...)

Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes (/sɜːrˈpɛntiːz/). Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more joints than their lizard ancestors, enabling them to swallow prey much larger than their heads (cranial kinesis). To accommodate their narrow bodies, snakes' paired organs (such as kidneys) appear one in front of the other instead of side by side, and most have only one functional lung. Some species retain a pelvic girdle with a pair of vestigial claws on either side of the cloaca. Lizards have independently evolved elongate bodies without limbs or with greatly reduced limbs at least twenty-five times via convergent evolution, leading to many lineages of legless lizards. These resemble snakes, but several common groups of legless lizards have eyelids and external ears, which snakes lack, although this rule is not universal (see Amphisbaenia, Dibamidae, and Pygopodidae). (Full article...)

The Mexican lance-headed rattlesnake or lance-headed rattlesnake (Crotalus polystictus) is a venomous pit viper species found in central Mexico. No subspecies is currently recognized. (Full article...)

Tropidolaemus wagleri, more commonly known as Wagler's pit viper, is a species of venomous snake, a pit viper in the subfamily Crotalinae of the family Viperidae. The species is endemic to Southeast Asia. There are no subspecies that are recognized as being valid. It is sometimes referred to as the temple viper because of its abundance around the Temple of the Azure Cloud in Malaysia. (Full article...)