Added 24 September 2003. Last updated 30 January 2014: updated introductory text and added link to Anomalepididae.

A Rough Guide to

THE SNAKE FAMILIES

What follows is a rough guide to the various families of the snakes around the world. This is technically known as the taxonomic classification of snakes. Apart from the interest value, it may help you when trying to ascertain care requirements for a particular species.

Snakes, lizards and amphisbaenians together form the Order Squamates. Snakes form the sub-order Serpentes, while lizards and amphisbaenians form the sub-orders Sauria and Amphisbaenia respectively.

The families of the snakes are grouped into three super-families, or ancestral lines: Typhlopoidea (also known as Scolecophidia), Henophidia (also known as Boidea), and Xenophidia (also known as Colubroidea or Caenophidia).

Finally it should be noted that snake taxonomy is in a state of constant revision at the moment, with families, orders, etc being shunted around every few years. Although the classification that follows is broadly correct (I have borrowed largely from Chris Mattison's Snakes of the World, 1989, but amended in the light of the classifications found at the JCVI/TIGR Reptile Database), you should be aware that it may change or that there are alternative models. Lest this sound too vague and woolly to be worth reading, I should add that the family descriptions at least are fairly accurate.

The term Old World is used here according to standard usage to include Europe, Africa, Asia and Australia. The term New World denotes the Americas.

The italicised name in brackets is the proper Latin scientific name.

Those families marked * are rather obscure. They may not be rare within their home range, but they are hardly ever seen in captivity and little is known of their natural history.

Note, January 2014: in the past ten years classification as a whole, and that of snakes, has undergone some major revisions. Therefore this page will hopefully soon be revised to take these changes into account. However, the basic grouping accounts to family/subfamily level (eg pythons, boas, blindsnakes, etc) are roughly sound.

Typhlopoidea line

*Anomalepidae (Dawn/Early Blind Snakes: 16 species in 4 genera)

These thread-like snakes are found only in tropical South America. They lack the vestigial pelvic girdle found in the other two families in their superfamily and have teeth on both upper and lower jaws.

Anomalepidae

*Typhlopidae (Blind Snakes: >220 species in 6 genera)

Small thread-like snakes (usually less than 1ft/30cm long, with the largest at 3ft) with glossy scales, a vestigial pelvic girdle and teeth on the upper jaw only. Their eyes are covered by scales, hence the common name. They also lack a left lung and left oviduct. Most are a brown colour. These snakes are more widely distributed than those of the other two families in the Typhlopoidea, being found in tropical parts of every continent in both Old and New World. They seem to prefer places where light is excluded (ie below the surface or inside structures such as rotten logs or termite mounds), but otherwise are fairly variable in habitat, from dry to moist areas. The blunt heads and blunt tails would appear to be an adaptation to a burrowing lifestyle. Most if not all species feed on the larvae and adults of termites and ants. There is still much to be learned about these snakes, but at least some are oviparous while Rhampotyphlops brahmini, the Flowerpot Snake, is considered to be parthogenetic.

*Leptotyphlopidae (Slender Blind Snakes/Worm Snakes: 93 species in 2 genera)

Considered to be the most primitive snakes, and also among the smallest, with the largest reaching 16"/40cm. Leptotyphlopids have a pelvic girdle, vestigial hind limbs and a single lung and oviduct. The eyes are small and the scales polished. Most are a darkish colour, with a few having an indistinct pattern. Their way of life is fossorial (burrowing), and the snakes are often associated with termite or ant nests. They are distributed across the tropical parts of America, all of Africa and western Asia.

Henophidia line

*Aniliidae (Pipe Snakes: 1 species)

The Aniliidae formerly included the Anomochilidae (Dwarf Pipe Snakes) and Cylindrophiidae (Asian Pipe Snakes), and the three families do share certain characteristics such as vestigial hind limbs and enlarged ventral plates as well as similarities in the skull structure, including a limited flexibility. The single species, Anilius scytale, is only found in northern South America. It is about 3ft long.

*Anomochilidae (Dwarf Pipe Snakes/False Blind Snakes: 2 species)

A single genus of two snakes from SE Asia formerly considered to be part of the same group as the Cylindrophiidae, which they superficially resemble.

Boidae (Boas and Pythons: ? species)

Boas and pythons need little introduction, although much commonly held thought about them (especially regarding size and danger) is actually myth or at best exaggeration. In common with the pipe snakes these also have vestigial hind limbs and enlarged ventral plates, but the Boidae also have much greater skull flexibility: the largest members of the family can kill and swallow deer and similar-sized mammals.

See also A Quick Guide to Boas: A Quick Guide to Pythons

*Bolyeridae (Round Island Boas: 2 species)

Until recently these were considered members of the Boidae, but differed in lacking pelvic girdle or vestigial limbs: subsequently they were reclassified. There are only two monotypic genera (ie one species each). Both are fully protected, and in any case their diet of lizards would probably be difficult for most keepers to provide.

Cylindrophiidae (Asian Pipe Snakes: 8 species)

A single genus of burrowing, ovoviviparous snakes, the largest of which reaches about 1m/3ft. They inhabit SE Asia. All have black and white checkered bellies: some also display aposematic coloration.

See Cylindrophidae

Uropeltidae (Shield-Tail Snakes: 45+ species)

A small group of snakes found in southern India and Sri Lanka. All are burrowers showing adaptations to this way of life, with pointed head, flexible neck, reduced eyes and polished scales. Their unique feature is however the single large scale at the end of the tail, usually rough and often bearing spines. The largest snake in this genus is about 1m/3ft long, but most are much smaller. They are rarely if ever seen in the pet trade.

Xenopeltidae (Sunbeam Snakes: 2 species)

An externally "typical"-looking snake but one which has proved impossible to class with either the colubrids or any other family, and which therefore exists in its own grouping. X. unicolor is found in SE Asia and adjacent areas and is somewhat glossy purple in appearance. It is occasionally offered in the pet trade. The other species, X. hainensis, is found in China and Taiwan.

See Xenopeltidae

Xenophidia

Acrochordidae (File or Wart Snakes: 3 species)

A small family of two genera of Asian aquatic snakes, sharing some characteristics with the Colubridae, but distinguished by their skin, which is loose and hangs in folds on their body. The scales are granular, uniquely among snakes. These snakes are valued chiefly for their hide ("karung") and are rarely seen in captivity since they do not adapt well.

See also Acrochordidae (File Snakes) page

Atractaspidae (Mole Vipers: ? species)

This group was formerly considered a subfamily of the Colubridae or as part of the Viperidae, and may still be regarded as either by some authorities. They differ from both however in the nature of their dentition and jaw. Basically they have few if any teeth other than fangs at the front of the upper jaw, which in most cases can be unfolded: unlike the true vipers, however, they simply move the lower jaw out of the way. Apart from being small (up to2-3ft), cylindrical and with short blunt tails and small eyes, the different groups are otherwise variable in ecology and anatomy. Most are not dangerous to man. Apart from a few species in the Middle East, all are found in Africa. There are 11 genera.

Colubridae (Colubrids or Typical Snakes: over 2000 species)

This constitutes by far the largest group of snakes, hence its common name of "typical snakes". The family is so vast, in fact, that it is divided into a large number of subfamilies. The vast majority are non-venomous, but some are "back-fanged" and a few of these can be dangerous to man. Recent research has indicated that venom may in fact be more widespread among the colubrids than was previously expected (Fry and Wüster), although it is stressed that this does not appear to apply to the commonly kept colubrids. In fact although many colubrids (eg Elaphe, Lampropeltis, Pituophis and Thamnophis) are usually good candidates for captivity, other lesser-known colubrids are not, for one reason or another (eg habitat or diet). Fortunately for those who are interested in them, the choice of suitable snakes is still quite large.

A broad introduction to the Colubridae : Colubridae listing by genus.

Elapidae (Cobras, Kraits, Mambas, Coral Snakes and Australian “adders”: ? species)

This family contains some of the most famous snakes in the world, as well as the most poisonous. Representative species are found in the tropical and subtropical parts of both Old and New Worlds, and most of Australia's venomous snakes are elapids. It is believed that the elapids evolved from the colubrids. Most do not grow exceptionally large, with the exception of the King Cobra (Ophiophagus hannah) which can reach a staggering 18ft, possibly because it preys entirely on other snakes. Elapids differ from the viper family principally in that their fangs are immovable, whereas those of vipers can be folded back in the mouth when not in use.

See also Elapids page.

Hydrophiidae (Sea Snakes: ? species)

The sea snakes are often considered to be a subfamily of the Elapidae, although they have their own physiological adaptations for an aquatic lifestyle. Nearly all are found in coastal waters in the Indopacific region, with none in the Atlantic, although Pelamis platurus (Yellow-Bellied Sea Snake) does reach the west coast of the Americas, having a staggeringly wide range that reaches as far west as the Persian Gulf and southern Africa. There are two subfamilies: the Laticaudinae, whose 5 species can move on land and which lay eggs on land, and the Hydrophiinae, all other sea snakes, which are helpless on land and which are ovoviparous. All are venomous, but not all are fatally toxic, and most (but not all) are fairly peaceful creatures.

See also Hydrophiidae (Sea Snakes) page.

*Viperidae (Vipers, Pit Vipers and non-Australian Adders: ? species)

Some authorities consider these to be the most advanced of all snakes, since they have such refinements as folding fangs and (in some species) heat-sensitive pits to facilitate hunting at night. Furthermore, most give birth to live young (either ovoviviparously or viviparously), which has allowed them to colonise mountains and deserts more than the other families. This group includes such well-known snakes as rattlesnakes, adders and Gaboon and Rhinoceros vipers.

See also Viperidae (Vipers) page.

Bibliography

Snakes of the World, Chris Mattison, Blandford, 1986/1992, London. A good book with the only reservation being that applied to Dieter Schmidt's, ie some of the taxonomy/classification is now out of date.

Reptiles and Amphibians of Australia, 6th edition, Harold Cogger, Reed New Holland, Australia, 2000.

"Herps 101: The Advanced Snakes", Jerry G Walls, Reptile & Amphibian Hobbyist 5:3. Useful article giving an overview of the families of the Xenophidia.

Links

The Reptile Database's current phylogeny of snakes, giving bibliographic sources.


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