Tuatara
Tuatara (tōˌətärˈə) [key] or tuatera –tāˈrə, lizardlike reptile, Sphenodon punctatus, last survivor of the reptilian order Rhynchocephalia, which flourished in the early Mesozoic era before the rise of the dinosaurs. Also called sphenodon, it is found on islands off the New Zealand coast and in Karori Wildlife Sanctuary, Wellington, New Zealand. The olive colored, yellow-speckled tuatara reaches a length of 2 ft (60 cm) or more. It is very lizardlike in external form, with a crest of spines down its neck and back. However, its internal anatomy, its scales, and the attachment of its teeth are quite different from those of lizards, and its body chemistry allows it to function at temperatures close to freezing. Like certain lizards, it possesses a vestigial third eye (pineal eye) on top of its head, but this organ is probably not sensitive to light. Tuataras usually inhabit the breeding burrows of certain small petrels. They feed on small animals, especially insects, and reproduce by laying eggs. Captive tuataras mature in about 20 years, and it appears that their life span may exceed a century by several decades.
Tuataras lived on the mainland of New Zealand before the arrival of the Maoris but either were exterminated by hunting or died out as a result of the altered environment. Their survival on the offshore islands was threatened by the introduction of sheep, which altered the vegetation by grazing; however, they are now under strict government protection, and their numbers are increasing. In 2005 tuataras were reintroduced on the mainland at the Karori Wildlife Sanctuary.
Tuataras are classified in the phylum Chordata, subphylum Vertebrata, class Reptilia, order Rhynchocephalia.
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Tuataras lived on the mainland of New Zealand before the arrival of the Maoris but either were exterminated by hunting or died out as a result of the altered environment. Their survival on the offshore islands was threatened by the introduction of sheep, which altered the vegetation by grazing; however, they are now under strict government protection, and their numbers are increasing. In 2005 tuataras were reintroduced on the mainland at the Karori Wildlife Sanctuary.
Tuataras are classified in the phylum Chordata, subphylum Vertebrata, class Reptilia, order Rhynchocephalia.
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Lizards
izard, a reptile of the order Squamata, which also includes the snake. Lizards form the suborder Sauria, and there are over 3,000 lizard species distributed throughout the world (except for the polar regions), with the greatest number found in warm climates. They range in size from gecko species under 3/4 in. (2 cm) long to the 10-ft (3-m) Komodo dragon (seemonitor) of SE Asia.
Lizards typically have four legs with five toes on each foot, although a few, such as the worm lizard and the so-called glass snake, are limbless, retaining only internal vestiges of legs. Lizards are also distinguished from snakes by having ear openings, movable eyelids, and less flexible jaws. As in snakes, there is a chemosensory organ opening in the roof of the mouth. The tongue, which may be short and wide, slender and forked, or highly extendible, conveys particles from the environment to this organ. The skin of the lizard is scaly and in most species is molted in irregular patches. Members of several lizard families, notably the chameleons, undergo color changes under the influence of environmental and emotional stimuli.
Many lizards are arboreal, and many terrestrial species are well adapted for climbing. They are often fast runners, some achieving speeds of over 15 mi (24 km) per hr. Some are adapted for burrowing. Most can swim and a few lead a semiaquatic existence, among them the single marine species, an iguana of the Galapagos Islands. Gliding forms, the flying dragons, are found in the forests of SE Asia. The gila monster and the related beaded lizard of the North American deserts are the only known poisonous lizards; some other lizards, such as the lace monitor of Australia, produce a nonfatal venom. Despite folklore, the bite of the gecko is not poisonous. Members of most species are carnivorous, feeding especially on insects, but some are herbivorous or omnivorous.
Fertilization is internal in lizards; males have paired copulatory organs, characteristic of the order. In most species females lay eggs, which they bury in the ground, but in some the eggs are incubated in the oviducts and hatched as they are laid. In both types the young have a special temporary tooth for rupturing the shell. In a few species there is true viviparity, or live birth, with the young nourished by a simple placenta.
The greatest number of species in the United States is found in the South and West. The majority are members of the iguana family, including the collared lizards, swifts, utas, horned lizards (popularly known as horned toads), and the so-called American chameleon, or anole. These are day-active lizards commonly seen basking on rocks. Most are valuable destroyers of insects.
Lizards are classified in the phylum Chordata, subphylum Vertebrata, class Reptilia, order Squamata, suborder Sauria.
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Lizards typically have four legs with five toes on each foot, although a few, such as the worm lizard and the so-called glass snake, are limbless, retaining only internal vestiges of legs. Lizards are also distinguished from snakes by having ear openings, movable eyelids, and less flexible jaws. As in snakes, there is a chemosensory organ opening in the roof of the mouth. The tongue, which may be short and wide, slender and forked, or highly extendible, conveys particles from the environment to this organ. The skin of the lizard is scaly and in most species is molted in irregular patches. Members of several lizard families, notably the chameleons, undergo color changes under the influence of environmental and emotional stimuli.
Many lizards are arboreal, and many terrestrial species are well adapted for climbing. They are often fast runners, some achieving speeds of over 15 mi (24 km) per hr. Some are adapted for burrowing. Most can swim and a few lead a semiaquatic existence, among them the single marine species, an iguana of the Galapagos Islands. Gliding forms, the flying dragons, are found in the forests of SE Asia. The gila monster and the related beaded lizard of the North American deserts are the only known poisonous lizards; some other lizards, such as the lace monitor of Australia, produce a nonfatal venom. Despite folklore, the bite of the gecko is not poisonous. Members of most species are carnivorous, feeding especially on insects, but some are herbivorous or omnivorous.
Fertilization is internal in lizards; males have paired copulatory organs, characteristic of the order. In most species females lay eggs, which they bury in the ground, but in some the eggs are incubated in the oviducts and hatched as they are laid. In both types the young have a special temporary tooth for rupturing the shell. In a few species there is true viviparity, or live birth, with the young nourished by a simple placenta.
The greatest number of species in the United States is found in the South and West. The majority are members of the iguana family, including the collared lizards, swifts, utas, horned lizards (popularly known as horned toads), and the so-called American chameleon, or anole. These are day-active lizards commonly seen basking on rocks. Most are valuable destroyers of insects.
Lizards are classified in the phylum Chordata, subphylum Vertebrata, class Reptilia, order Squamata, suborder Sauria.
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Snakes
Snake, common name for an elongated, limbless reptile of the order Squamata, which also includes the xlizards. Most snakes live on the ground, but some are burrowers, arboreal, or aquatic; one group is exclusively marine. In temperate climates they hibernate. They are generally solitary in their habits, although they may congregate in places offering food or shelter, and large numbers may hibernate together. Snakes range in length from about 4 in. (10 cm) to over 30 ft (9 m). Most are protectively colored.
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Turtles
Turtle, a reptile of the order Chelonia, with strong, beaked, toothless jaws and, usually, an armorlike shell. The shell normally consists of bony plates overlaid with horny shields. The upper portion, or carapace, covers the turtle's back and sides, and the lower portion, or plastron, covers the belly; the two parts are joined at the sides. Exceptions are the rare plateless turtles of New Guinea and the marine leatherback turtle, which is encased in a thick, ossified skin resembling a carapace. When startled, most turtles withdraw their heads straight back into their shells, the neck folding into an S-shaped curve. However, in the side-necked turtles of the Southern Hemisphere, the head moves sideways and tucks next to the shoulder.Turtles are found throughout most of the temperate and tropical world and in the open ocean; of the 270 known species, 42% are rare or threatened with extinction. Many turtles and their eggs are valued as food. Edible species include several marine turtles, the green turtle (traditional ingredient of turtle soup), the diamondback terrapin, and the soft-shelled turtles. Catching females when they lay eggs on land has contributed to a serious decline in many species, since it can take 10 to 30 years for some turtles to reach sexual maturity.
Different types of turtle are variously adapted to living on land, in freshwater, or in the ocean, but all turtles breathe by means of lungs (though some freshwater turtles also can absorb oxygen from the water through their skin or other means), and all lay eggs on land. The land-living species, especially those of the family Testudinidae, are commonly called tortoises. The name terrapin is generally applied to large freshwater or brackish water species, especially those used for food. Turtle species are either herbivorous or carnivorous but rarely both. They range in length from a few inches to over 6 ft (2 m), most being between 5 in. and 15 in. (13–38 cm) long. Many specimens have survived more than 50 years in captivity; one giant tortoise is known to have lived for 176 years, and another is believed to have lived about 250 years. Even larger giant turtles, some 8 ft (2.5 m) in length, lived c.3,000 years ago in the Pacific on Efate island, Vanuatu, dying out after the arrival of humans there. The largest known fossil turtle, Archelon ischyros, a sea turtle that lived during the late Cretaceous, was 15 ft (4.5 m) long.
Turtles existed 200 million years ago, at the time of the earliest dinosaurs; these early land-dwelling turtles could not retract their necks. By 120 million years ago some turtles had adapted to an aquatic life, although a 220-million-year-old ancestor of turtles that had only a bony breastplate may have been aquatic. Many of the living families of turtles existed in the Cretaceous period and have undergone very little change since then. On the basis of morphological (body structure) evidence, turtles were thought to be the oldest surviving group of reptiles. However, molecular studies comparing genes in different reptile groups indicate that turtles, along with crocodiles, are the most modern of reptiles.
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Different types of turtle are variously adapted to living on land, in freshwater, or in the ocean, but all turtles breathe by means of lungs (though some freshwater turtles also can absorb oxygen from the water through their skin or other means), and all lay eggs on land. The land-living species, especially those of the family Testudinidae, are commonly called tortoises. The name terrapin is generally applied to large freshwater or brackish water species, especially those used for food. Turtle species are either herbivorous or carnivorous but rarely both. They range in length from a few inches to over 6 ft (2 m), most being between 5 in. and 15 in. (13–38 cm) long. Many specimens have survived more than 50 years in captivity; one giant tortoise is known to have lived for 176 years, and another is believed to have lived about 250 years. Even larger giant turtles, some 8 ft (2.5 m) in length, lived c.3,000 years ago in the Pacific on Efate island, Vanuatu, dying out after the arrival of humans there. The largest known fossil turtle, Archelon ischyros, a sea turtle that lived during the late Cretaceous, was 15 ft (4.5 m) long.
Turtles existed 200 million years ago, at the time of the earliest dinosaurs; these early land-dwelling turtles could not retract their necks. By 120 million years ago some turtles had adapted to an aquatic life, although a 220-million-year-old ancestor of turtles that had only a bony breastplate may have been aquatic. Many of the living families of turtles existed in the Cretaceous period and have undergone very little change since then. On the basis of morphological (body structure) evidence, turtles were thought to be the oldest surviving group of reptiles. However, molecular studies comparing genes in different reptile groups indicate that turtles, along with crocodiles, are the most modern of reptiles.
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Crocodile
Crocodile, large, carnivorous reptile of the order Crocodilia, found in tropical and subtropical regions. Crocodiles live in swamps or on river banks and catch their prey in the water. They have flattened bodies and tails, short legs, and powerful jaws. The eyes, ears, and nostrils are located near the top of the head and are exposed when the crocodile floats on the surface of the water. The ears and nostrils have valves that close when the animal is submerged.
Most crocodiles are more aggressive than the related alligators. The two forms are distinguished by the long lower fourth tooth: in crocodiles, but not in alligators, this tooth protrudes on the side of the head when the mouth is closed. Also, the snouts of most crocodiles are narrower than those of alligators.
Small crocodiles feed on fish and small aquatic animals; larger ones also catch land mammals and birds that approach the water. Members of some large species sometimes attack and eat humans. The female crocodile deposits her eggs, usually about 20 in number, in a nest of rotting vegetation or in a shallow pit on the river bank, and digs them up when she hears them hatching.
In most species the average adult length is between 6 and 10 ft (1.8–3 m). The largest crocodile (the saltwater crocodile) is often 14 ft (4.3 m) long and may exceed 20 ft (6 m) in length. The Nile, American, and Orinoco crocodiles are commonly 12 ft (3.7 m) long, and specimens up to 23 ft (7 m) long have been reported for the last two species. The extinctSarcosuchus imperator, which lived during the Cretaceous period, may have approached 40 ft (12 m) in length. The smallest crocodile (the Congo dwarf crocodile) averages 31/2 ft (105 cm) long.
With the exception of the two African dwarf crocodiles ( Osteolaemus ) and the so-called false gavial ( Tomistoma ) of Asia, crocodiles are classified in the genus Crocodylus, with about a dozen species. The Nile crocodile ( C. niloticus ) is found in fresh- and saltwater throughout S and central Africa. In early historic times it ranged N to the Nile delta and the Mediterranean coast. It sometimes attacks humans, as does the saltwater crocodile ( C. porosus ), found on islands and in straits from SE Asia to Australia and Melanesia. The marsh crocodile, or mugger ( C. palustris ), is a freshwater species of India and Sri Lanka, regarded as sacred in some regions. The American crocodile ( C. acutus ) is found in fresh- and saltwater in S Florida, the West Indies, Central America, and NW South America. It does not attack humans without provocation. The Orinoco crocodile ( C. intermedius ) is a freshwater species of the Orinoco basin of Colombia and Venezuela. Two smaller species are found in limited areas of Central America and Cuba.
Crocodiles are classified in the phylum Chordata, subphylum Vertebrata, class Reptilia, order Crocodilia, family Crocodilidae.
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Most crocodiles are more aggressive than the related alligators. The two forms are distinguished by the long lower fourth tooth: in crocodiles, but not in alligators, this tooth protrudes on the side of the head when the mouth is closed. Also, the snouts of most crocodiles are narrower than those of alligators.
Small crocodiles feed on fish and small aquatic animals; larger ones also catch land mammals and birds that approach the water. Members of some large species sometimes attack and eat humans. The female crocodile deposits her eggs, usually about 20 in number, in a nest of rotting vegetation or in a shallow pit on the river bank, and digs them up when she hears them hatching.
In most species the average adult length is between 6 and 10 ft (1.8–3 m). The largest crocodile (the saltwater crocodile) is often 14 ft (4.3 m) long and may exceed 20 ft (6 m) in length. The Nile, American, and Orinoco crocodiles are commonly 12 ft (3.7 m) long, and specimens up to 23 ft (7 m) long have been reported for the last two species. The extinctSarcosuchus imperator, which lived during the Cretaceous period, may have approached 40 ft (12 m) in length. The smallest crocodile (the Congo dwarf crocodile) averages 31/2 ft (105 cm) long.
With the exception of the two African dwarf crocodiles ( Osteolaemus ) and the so-called false gavial ( Tomistoma ) of Asia, crocodiles are classified in the genus Crocodylus, with about a dozen species. The Nile crocodile ( C. niloticus ) is found in fresh- and saltwater throughout S and central Africa. In early historic times it ranged N to the Nile delta and the Mediterranean coast. It sometimes attacks humans, as does the saltwater crocodile ( C. porosus ), found on islands and in straits from SE Asia to Australia and Melanesia. The marsh crocodile, or mugger ( C. palustris ), is a freshwater species of India and Sri Lanka, regarded as sacred in some regions. The American crocodile ( C. acutus ) is found in fresh- and saltwater in S Florida, the West Indies, Central America, and NW South America. It does not attack humans without provocation. The Orinoco crocodile ( C. intermedius ) is a freshwater species of the Orinoco basin of Colombia and Venezuela. Two smaller species are found in limited areas of Central America and Cuba.
Crocodiles are classified in the phylum Chordata, subphylum Vertebrata, class Reptilia, order Crocodilia, family Crocodilidae.
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Aves
any warm-blooded vertebrate of the class Aves, having a body covered with feathers, forelimbs modified into wings, scaly legs, a beak, and no teeth, and bearing young in a hard-shelled egg.
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