Elapidae

Elapidae
Cobras are part of the Elapidae family
Scientific classification
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Reptilia Order: Squamata Suborder: Serpentes Family: Elapidae F. Boie, 1827 Subfamily: Elapinae Hydrophiinae Laticaudinae

Elapidae (Greek ἔλλοψ éllops, "sea-fish") is a major family of venomous snakes found in tropical and subtropical regions around the world, terrestrially in Asia, Australia, Africa, North America and South America and aquatically in the Pacific and Indian Oceans. Elapid snakes exist in a wide range of sizes, from 18 cm species of Drysdalia to the 5.6 m (18 ft) Ophiophagus hannah (King cobra), and are characterized by hollow, fixed fangs through which they inject venom. Currently, 61 genera that include 325 species are recognized.

Taxonomy

In the past, many subfamilies were recognized, or have been suggested for the Elapidae, including the Elapinae, Hydrophiinae (sea snakes), Micrurinae (coral snakes), Acanthophiinae (Australian elapids) and the Laticaudinae (sea kraits). Currently, none are universally recognized. There is now good molecular evidence via karyotyping and protein electrophoretic analysis, immunological distance, DNA sequence analysis etc. for reciprocal monophyly of two groups: the African, Asian and New World Elapinae, and Australasian and marine Hydrophiinae. Thus, the Australian terrestrial elapids are 'hydrophiines', though not sea snakes, while it is believed that Laticauda and the 'true sea snakes' evolved separately from among the Australasian land-snakes. Asian cobras, coral snakes, and American coral snakes also appear to be monophyletic, while African cobras do not.

The type genus for the Elapidae was originally Elaps, but that group was moved to another family. In contrast to what usually happens in botany, the Elapidae family was not renamed. In the meantime, Elaps was renamed Homoroselaps and moved back to the Elapidae. However, Nagy et al. 2005 regard it as a sister taxon to Atractaspis which should therefore have been assigned to the Atractaspididae.

Description

In an examination of morphological characters, concluded that elapids fall into two groups: the palatine draggers and palatine erectors. "Palatine draggers" include Australasian terrestrial elapids (except Parapistocalamus) and hydrophiine sea snakes. In these species, the palatine acts as an anterior extension of the pterygoid, remaining horizontal even when the maxilla is erected. The "palatine erectors" include terrestrial African, Asian, and American elapids, the marine Laticauda, and Parapistocalamus. In these species, the palatine is erected along with the maxilla during protraction of the palate (McDowell, 1970). McDowell’s hypothesis was used in the snake classification of Smith et al. (1977), who divided Elapidae sensu lato into Elapidae sensu stricto and Hydrophiidae for the palatine erectors and draggers, respectively.

All elapids have a pair of proteroglyphous fangs that are used to inject venom from glands located towards the rear of the upper jaws. In outward appearance terrestrial elapids look similar to the family Colubridae: almost all have long and slender bodies with smooth scales, a head that is covered with large shields and not always distinct from the neck, and eyes with round pupils. In addition, their behavior is usually quite active and most are oviparous. There are exceptions to all these generalizations, for example, the death adders (Acanthophis) include short and fat, rough-scaled, very broad-headed, cat-eyed, live-bearing, sluggish ambush predators with partly fragmented head shields.

Some elapids are strongly arboreal (African Pseudohaje and Dendroaspis, Australian Hoplocephalus), while many others are more or less specialised burrowers (e.g. Ogmodon, Parapistocalamus, Simoselaps, Toxicocalamus, Vermicella) in either humid or arid environments. Some species have very generalised diets, but many taxa have narrow prey preferences (stenophagy) and correlated morphological specialisations, e.g. for feeding on other snakes, elongate burrowing lizards, squamate eggs, mammals, birds, frogs, fish and others.

Sea snakes (Hydrophiinae, sometimes considered to be a separate family) have adapted to a marine way of life in different ways and to various degrees. All have evolved paddle-like tails for swimming and the ability to excrete salt. Most also have laterally compressed bodies, ventral scales are much reduced in size, their nostrils are located dorsally (no internasal scales) and give birth to live young (ovoviviparous). In general, they have the ability to respire through their skin; experiments with the yellow-bellied sea snake, Pelamis platurus, have shown that this species can satisfy about 20% of its oxygen requirements in this manner, allowing for prolonged dives. The sea kraits (Laticaudinae), are the sea snakes least adapted to an aquatic life. They spend much of their time on land, where they lay their eggs. They have wide ventral scales, the tail is not as well-developed for swimming, and their nostrils are separated by internasal scales.

Geographic distribution

On land, these snakes are found worldwide in tropical and subtropical regions, except in Europe. They occur in Africa, Asia, Oceania (Australia), the Middle East, North America and South America. Sea snakes occur mainly in the Indian Ocean and the southwest Pacific Ocean. However, the range of one species, Pelamis platura, extends across the Pacific to the coasts of Central and South America.

Venom

All elapids are venomous snakes which are potentially deadly. Their venom is mainly neurotoxic, although many of them also possess several other toxins, including cardiotoxin and cytotoxin. Some large-sized elapids, such as the Asiatic king cobra, African black mamba, and Australasian coastal taipan, can inject a high quantity of venom during envenomation. Elapids use their venom both to immobilize their prey and in self defense. The most venomous snake in the world is Belcher's sea snake, but on land the Inland taipan is considered to be the most venomous with a subcutaneous LD₅₀ of 0.025 mg/kg.

Genera

Genus	Taxon author	Species	Sub-species*	Common name	Geographic range
Acalyptophis	Boulenger, 1869	1	0	spiny-headed seasnake	Gulf of Thailand, South China Sea, the Strait of Taiwan, and the coasts of Guangdong, Indonesia, Philippines, New Guinea, New Caledonia, Australia (Northern Territory, Queensland, Western Australia)
Acanthophis	Daudin, 1803	7	0	death adders	Australia, New Guinea, Indonesia (Seram and Tanimbar)
Aipysurus	Lacépède, 1804	7	1	olive sea snakes	Timor Sea, South China Sea, Gulf of Thailand, and coasts of Australia (Northern Territory, Queensland, Western Australia), New Caledonia, Loyalty Islands, southern New Guinea, Indonesia, western Malaysia and Vietnam
Aspidelaps	Fitzinger, 1843	2	4	shieldnose cobras	South Africa (Cape Province, Transvaal), Namibia, southern Angola, Botswana, Zimbabwe, Mozambique
Aspidomorphus	Fitzinger, 1843	3	3	collared adders	New Guinea.
Astrotia	Fischer, 1855	1	0	Stokes' sea snake	Coastal areas from west India and Sri Lanka through Gulf of Thailand to China Sea, west Malaysia, Indonesia east to New Guinea, north and east coasts of Australia, Philippines
Austrelaps	Worrell, 1963	3	0	copperheads	Australia (South Australia, New South Wales, Victoria, Tasmania)
Boulengerina	Dollo, 1886	2	1	water cobras	Cameroon, Gabon, Democratic Republic of the Congo, Congo, Central African Republic, Tanzania, Equatorial Guinea, Rwanda, Burundi, Zambia
Bungarus	Daudin, 1803	12	4	kraits	India (incl. Andaman Island), Myanmar, Nepal, Vietnam, Afghanistan, Pakistan, Sri Lanka, Bangladesh, Cambodia, Indonesia (Java, Sumatra, Bali, Sulawesi), Peninsular Malaysia, Singapore, Taiwan, Thailand
Cacophis	Günther, 1863	4	0	rainforest crowned snakes	Australia (New South Wales, Queensland)
Calliophis	Gray, 1834	8	11	Oriental coral snakes	India, Bangladesh, Sri Lanka, Nepal, Indonesia, Cambodia, Malaysia, Singapore, Thailand, Burma, Brunei, Philippines, Vietnam, Laos, southern China, Japan (Ryukyu Islands), Taiwan
Demansia	[Gray, 1842	9	2	whipsnakes	New Guinea, continental Australia
Dendroaspis	Schlegel, 1848	4	1	mambas	Kenya, Tanzania, Mozambique, Malawi, Zimbabwe, South Africa, Ghana, Togo, Benin, Nigeria, Cameroon, Guinea, Gabon, Principe (Gulf of Guinea), Central African Republic, Democratic Republic of the Congo, Congo, Uganda, Rwanda, Burundi, Equatorial Guinea, Angola, Sudan, Botswana, Burkina Faso, Eritrea, Senegal, Mali, Ethiopia, Ivory Coast, Namibia, Somalia, Swaziland, Zambia, Gambia, Guinea Bissau, Liberia, Ivory Coast, Sierra Leone
Denisonia	Krefft, 1869	2	0	ornamental snakes	Central Queensland and central northern New South Wales, Australia
Drysdalia	Worrell, 1961	3	0	southeastern grass snakes	Southern Australia (Western Australia, South Australia, Victoria, Tasmania, New South Wales)
Echiopsis	Fitzinger, 1843	1	0	bardick	Southern Australia (Western Australia, South Australia, Victoria, New South Wales)
Edichnopsis	Young, 2009	2	0	Sebastian cobra (separate species)	India, Sri Lanka, Nepal, Bhutan, South east China (including Tibet and Hong Kong), Northern Burma, Laos and Vietnam. Also found in Southern Cambodia
Elapognathus	Boulenger, 1896	2	0	southwestern grass snakes	Western Australia
Elapsoidea	Bocage, 1866	10	7	African or venomous garter snakes (not related to North American garter snakes, which are nonvenomous)	Senegal, South Africa, Mozambique, Namibia, Botswana, Zimbabwe, Swaziland, Gambia, Angola, Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Ghana, Ivory Coast, Malawi, Mali, Mauritania, Niger, Nigeria, Uganda, Senegal, Sudan, Tanzania, Togo, Democratic Republic of the Congo, Congo, Zambia, Kenya, north Burundi, Rwanda, Ethiopia, Uganda, Somalia
Emydocephalus	Krefft, 1869	2	0	turtlehead sea snakes	The coasts of Timor (Indonesian sea), New Caledonia, Australia (Northern Territory, Queensland, Western Australia), and in the Southeast Asian Sea along the coasts of China, Taiwan, Japan, and the Ryukyu Island
Enhydrina	Gray, 1849	2	0	beaked sea snakes	In the Persian Gulf (Oman, United Arab Emirates, etc.), south to the Seychelles and Madagascar, SE Asian Sea (Pakistan, India, Bangladesh, Myanmar, Thailand, Vietnam), Australia (North Territory, Queensland), New Guinea and Papua New Guinea
Ephalophis	M.A. Smith, 1931	1	0	Grey's mudsnake	Northwestern Australia
Furina	Duméril, 1853	3	0	pale-naped snakes	Mainland Australia
Glyphodon	Günther, 1858	2	0	brown-headed snakes	Australia (Queensland), New Guinea
Hemachatus	Fleming, 1822	1	0	spitting cobra	South Africa, Zimbabwe, Lesotho, Swaziland
Hemiaspis	Fitzinger, 1861	2	0	swamp snakes	Eastern Australia (New South Wales, Queensland)
Hemibungarus	Peters, 1862	1	2	Asian coral snakes	Taiwan, Japan (Ryukyu Islands)
Homoroselaps	Jan, 1858	2	0	harlequin snakes	South Africa
Hoplocephalus	[Wagler, 1830	3	0	broad-headed snakes	Eastern Australia (New South Wales, Queensland)
Hydrelaps	Boulenger, 1896	1	0	Port Darwin mudsnake	Northern Australia, southern New Guinea
Hydrophis	Latreille In Sonnini & Latreille, 1801	34	3	sea snakes	Indoaustralian and Southeast Asian waters.
Kerilia	[Gray, 1849	1	0	Jerdon's sea snake	Southeast Asian waters
Kolpophis	M.A. Smith, 1926	1	0	bighead sea snake	Indian Ocean
Lapemis	Gray, 1835	1	1	Shaw's sea snake	Persian Gulf to Indian Ocean, South China Sea, Indo-Australian archipelago and the western Pacific
Laticauda	Laurenti, 1768	5	0	sea kraits	Southeast Asian and Indoaustralian waters
Leptomicrurus	K.P. Schmidt, 1937	4	2	blackback coral snake	Northern South America
Loveridgelaps	McDowell, 1970	1	0	Solomons small-eyed snake	Solomon Islands
Micropechis	Boulenger, 1896	1	0	New Guinea small-eyed snake	New Guinea
Micruroides	K.P. Schmidt, 1928	1	2	Western coral snakes	USA (Arizona, southwestern New Mexico), Mexico (Sonora, Sinaloa)
Micrurus	Wagler, 1824	69	54	coral snakes	Southern North America, South America
Naja	[Laurenti, 1768	23	3	cobras	Africa, Asia
Notechis	Boulenger, 1896	2	0	tiger snakes	Southern Australia, including many offshore islands
Ogmodon	Peters, 1864	1	0	bola	Fiji
Ophiophagus	Günther, 1864	1	0	king cobra	Bangladesh, Myanmar, Cambodia, China, India, Andaman Islands, Indonesia, Laos, Thailand, Vietnam, west Malaysia, Philippines
Oxyuranus	Kinghorn, 1923	2	2	taipans	Australia, New Guinea
Parahydrophis	Burger & Natsuno, 1974	1	0	Northern mangrove sea snake	Northern Australia, southern New Guinea
Paranaja	Loveridge, 1944	1	2	many-banded snakes	West/central Democratic Republic of the Congo, Congo, Cameroon
Parapistocalamus	Roux, 1934	1	0	Hediger's snake	Bougainville Island, Solomons
Paroplocephalus	Keogh, Scott & Scanlon, 2000	1	0	Lake Cronin snake	Western Australia
Pelamis	Daudin, 1803	1	0	yellow-bellied sea snake	Indian and Pacific Oceans
Praescutata viperina	Wall, 1921	1	0	viperine sea snake	Persian Gulf, Indian Ocean, South Chinese Sea northeast to coastal region of Fujian and Strait of Taiwan
Pseudechis	Wagler, 1830	7	0	black snakes (and king brown)	Australia
Pseudohaje	Günther, 1858	2	0	forest cobras	Angola, Burundi, Cameroon, Central African Republic, Democratic Republic of the Congo, Congo, Gabon, Ghana, Kenya, Nigeria, Rwanda, Uganda, Sierra Leone, Liberia, Ivory Coast, Togo, Nigeria
Pseudonaja	Günther, 1858	8	2	venomous brown snakes (and dugites)	Australia
Rhinoplocephalus	Müller, 1885	6	0	Australian small-eyed snakes	Southern and eastern Australia, southern New Guinea
Salomonelaps	McDowell, 1970	1	0	Solomons coral snake	Solomon Islands
Simoselaps	Jan, 1859	13	3	Australian coral snakes	Mainland Australia
Sinomicrurus (Calliophis) macclellandi	Slowinski et al., 2001	5	4	MacClelland’s (Asian) coral snake	India, Myanmar, Vietnam, China, Taiwan, Japan
Suta	Worrell, 1961	10	2	hooded snakes (and curl snake)	Australia
Thalassophis	P. Schmidt, 1852	1	0	anomalous sea snake	South Chinese Sea (Malaysia, Gulf of Thailand), Indian Ocean (Sumatra, Java, Borneo)
Toxicocalamus	Boulenger, 1896	9	0	New Guinea forest snakes	New Guinea (and nearby islands)
Tropidechis	Günther, 1863	2	0	rough-scaled snake	Eastern Australia
Vermicella	[Gray In Günther, 1858	5	0	bandy-bandies	Australia
Walterinnesia	Lataste, 1887	2	0	black desert cobra	Egypt, Israel, Lebanon, Syria, Jordan, Iraq, Iran, Kuwait, Saudi Arabia, Turkey

* Not including the nominate subspecies