| Snakes | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Clade: | Ophidia |
| Suborder: | Serpentes Linnaeus, 1758 |
This is an overview of the suborder Serpentes, its two infraorders (subdivisions) and the families they contain. This is the group of reptiles commonly known as snakes.
There are two infraorders of living snakes: Alethinophidia and Scolecophidia. This separation is based primarily on morphological characteristics between family groups; however, more recently, the comparison of mitochondrial DNA has played its part.
As with most taxonomic classifications, there are many different interpretations of the evolutionary relationships. This had resulted in families being moved to different infraorders, the merging or splitting of infraorders and families. For instance, many sources classify Boidae and Pythonidae as the same family, or keep others, such as Elapidae and Hydrophiidae, separate for practical reasons despite their extremely close relationship.
| Alethinophidia 15 families | |||
| Family | Common Names | Example Species | Example Photo |
|---|---|---|---|
| Acrochordidae Bonaparte, 1831 | File snakes | Arafura file snake ( Acrochordus arafurae ) |  |
| Aniliidae Stejneger, 1907 | Coral pipe snakes | False coral snake ( Anilius scytale ) |  |
| Anomochilidae Cundall, Wallach and Rossman, 1993 | Dwarf pipe snakes | Leonard's pipe snake, ( Anomochilus leonardi ) | |
| Atractaspididae Günther, 1858 | Mole vipers | Western purple-glossed snake ( Amblyodipsas unicolor ) |  |
| Boidae Gray, 1825 | Boas | Amazon tree boa ( Corallus hortulanus ) |  |
| Bolyeridae Hoffstetter, 1946 | Round island boas | Round Island burrowing boa ( Bolyeria multocarinata ) | |
| Colubridae Oppel, 1811 | Colubrids | Grass snake ( Natrix natrix ) |  |
| Cylindrophiidae Fitzinger, 1843 | Asian pipe snakes | Red-tailed pipe snake ( Cylindrophis ruffus ) |  |
| Elapidae Boie, 1827 | Cobras, coral snakes, mambas, kraits, sea snakes, sea kraits, Australian elapids | King cobra ( Ophiophagus hannah ) |  |
| Loxocemidae Cope, 1861 | Mexican burrowing snakes | Mexican burrowing snake ( Loxocemus bicolor ) |  |
| Pythonidae Fitzinger, 1826 | Pythons | Indian python ( Python molurus ) |  |
| Tropidophiidae Brongersma, 1951 | Dwarf boas | Dusky dwarf boa ( Tropidophis melanurus ) | |
| Uropeltidae Müller, 1832 | Shield-tailed snakes, short-tailed snakes | Ocellated shield-tail ( Uropeltis ocellatus ) | |
| Viperidae Oppel, 1811 | Vipers, pitvipers, rattlesnakes | European asp ( Vipera aspis ) |  |
| Xenopeltidae Bonaparte, 1845 | Sunbeam snakes | Sunbeam snake ( Xenopeltis unicolor ) | |
| Scolecophidia 3 families | |||
| Family | Common Names | Example Species | Example Photo |
| Anomalepidae Taylor, 1939 | Dawn blind snakes | Dawn blind snake ( Liotyphlops beui ) | |
| Leptotyphlopidae Stejneger, 1892 | Slender blind snakes | Texas blind snake ( Leptotyphlops dulcis ) |  |
| Typhlopidae Merrem, 1820 | Blind snakes | Black blind snake ( Typhlops reticulatus ) | |
Lizards are a widespread group of squamate reptiles, with over 6,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic as it excludes the snakes and Amphisbaenia; 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.
Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes. 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 with their highly mobile jaws. To accommodate their narrow bodies, snakes' paired organs 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 evolved elongate bodies without limbs or with greatly reduced limbs about twenty-five times independently 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.
The Heteroptera are a group of about 40,000 species of insects in the order Hemiptera. They are sometimes called "true bugs", though that name more commonly refers to the Hemiptera as a whole. "Typical bugs" might be used as a more unequivocal alternative, since the heteropterans are most consistently and universally termed "bugs" among the Hemiptera. "Heteroptera" is Greek for "different wings": most species have forewings with both membranous and hardened portions ; members of the primitive sub-group Enicocephalomorpha have completely membranous wings.
The Mygalomorphae, or mygalomorphs, are an infraorder of spiders, and comprise one of three major groups of living spiders with over 3000 species, found on all continents except Antarctica. Many members are known as trapdoor spiders due to them forming trapdoors over their burrows. Other prominent groups include Australian funnel web spiders, and tarantulas, with the latter accounting for around one third of all mygalomorphs.
Squamata is the largest order of reptiles, comprising lizards, snakes, and amphisbaenians, which are collectively known as squamates or scaled reptiles. With over 10,900 species, it is also the second-largest order of extant (living) vertebrates, after the perciform fish. Members of the order are distinguished by their skins, which bear horny scales or shields. They also possess movable quadrate bones, making possible movement of the upper jaw relative to the neurocranium. This is particularly visible in snakes, which are able to open their mouths very wide to accommodate comparatively large prey. Squamata is the most variably sized order of reptiles, ranging from the 16 mm (0.63 in) dwarf gecko to the 6.5 m (21 ft) Reticulated python and the now-extinct mosasaurs, which reached lengths over 14 m (46 ft).
Amphisbaenia 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 the snakes 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. They are not found east of the Caspian Sea. Most species are less than 6 inches (150 mm) long.
The Anomochilidae, or anomochilids, are a monotypic family of snakes, created for the genus Anomochilus, which currently contains three species. It is commonly called dwarf pipe snake.
Acanthophis is a genus of elapid snakes. Commonly called death adders, they are native to Australia, New Guinea and nearby islands, and are among the most venomous snakes in the world. Despite their common name, they are not adders at all and belong to the Elapidae family. The name of the genus derives from the Ancient Greek akanthos/ἄκανθος ('spine') and ophis/ὄφις ('snake'), referring to the spine on the death adder's tail.
Dinosaur classification began in 1842 when Sir Richard Owen placed Iguanodon, Megalosaurus, and Hylaeosaurus in "a distinct tribe or suborder of Saurian Reptiles, for which I would propose the name of Dinosauria." In 1887 and 1888 Harry Seeley divided dinosaurs into the two orders Saurischia and Ornithischia, based on their hip structure. These divisions have proved remarkably enduring, even through several seismic changes in the taxonomy of dinosaurs.
The Uropeltidae, also known commonly as the shieldtails or the shield-tailed snakes, are a family of primitive, nonvenomous, burrowing snakes native to peninsular India and Sri Lanka. The name is derived from the Greek words ura ('tail') and pelte ('shield'), indicating the presence of the large keratinous shield at the tip of the tail. Seven or eight genera are recognized, depending on whether Teretrurus rhodogaster is treated in its own genus or as part of Brachyophidium. The family comprises over 50 species. These snakes are not well known in terms of their diversity, biology, and natural history.
Toxicofera is a proposed clade of scaled reptiles (squamates) that includes the Serpentes (snakes), Anguimorpha and Iguania. Toxicofera contains about 4,600 species, of extant Squamata. It encompasses all venomous reptile species, as well as numerous related non-venomous species. There is little morphological evidence to support this grouping, however it has been recovered by all molecular analyses as of 2012.
Xenotyphlops is a genus of snakes, the only genus of the family Xenotyphlopidae, comprising two species found only in Madagascar. These snakes are also known as the Malagasy Blind Snake.
The Scolecophidia, commonly known as blind snakes or thread snakes, are an infraorder of snakes. They range in length from 10 to 100 centimetres. All are fossorial. Five families and 39 genera are recognized. The Scolecophidia infraorder is most likely paraphyletic.
The Alethinophidia are an infraorder of snakes that includes all snakes other than blind snakes and thread snakes. Snakes have long been grouped into families within Alethinophidia based on their morphology, especially that of their teeth. More modern phylogenetic hypotheses using genetic data support the recognition of 19 extant families, although the taxonomy of alethinophidian snakes has long been debated, and ultimately the decision whether to assign a particular clade to a particular Linnaean rank is arbitrary.
The Colubroides are a clade in the suborder Serpentes (snakes). It contains over 85% of all the extant species of snakes. The largest family is Colubridae, but it also includes at least six other families, at least four of which were once classified as "Colubridae" before molecular phylogenetics helped in understanding their relationships. It has been found to be monophyletic.