Elapidae

Elapidae
Egyptian cobra, Naja haje
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Vertebrata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Infraorder:	Alethinophidia
Family:	Elapidae F. Boie, 1827
Subfamily:	Elapinae Hydrophiinae Laticaudinae

The Elapidae (Greek ἔλλοψ éllops, "sea-fish") are a 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 exhibit a wide range of sizes, from 18-cm species of Drysdalia to the 5.6-m king cobra. All elapids are characterized by hollow, fixed fangs through which they inject venom. Currently, 325 species in 61 genera are recognized; 58 genera and 251 species are in the Old World, against a minor diversity of three genera and 74 species in the New World.

Description

All elapids have a pair of proteroglyphous fangs used to inject venom from glands located towards the rear of the upper jaws. In outward appearance, terrestrial elapids look similar to the Colubridae: almost all have long and slender bodies with smooth scales, a head 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. Exceptions to all these generalizations occur: e.g. 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, and Vermicella) in either humid or arid environments. Some species have very generalised diets (euryophagy), but many taxa have narrow prey preferences (stenophagy) and correlated morphological specialisations, e.g. for feeding on other snakes, elongated burrowing lizards, squamate eggs, mammals, birds, frogs, fish, etc.

Sea snakes (the 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, their ventral scales are much reduced in size, their nostrils are located dorsally (no internasal scales), and they 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 (Laticauda spp.) are the sea snakes least adapted to aquatic life. They spend much of their time on land, where they lay their eggs. They have wide ventral scales, their tails are not as well-developed for swimming, and their nostrils are separated by internasal scales.

Dentition

The fangs, which are enlarged and hollow, are the first two teeth on each maxillary bone. Usually only one fang is in place on each side at any time. The maxilla is intermediate in both length and mobility between typical colubrids (long, less mobile) and viperids (very short, highly mobile). When the mouth is closed, the fangs fit into grooved slots in the buccal floor and usually below the front edge of the eye and are angled backwards; some elapids (Acanthophis, Oxyuranus, Dendroaspis, and Ophiophagus) have long fangs on quite mobile maxillae and can make fast strikes.

A few species are capable of spraying their venom from forward-facing holes at the tips of their fangs using pressure, and this can act as a means of defense.

Distribution

On land, these snakes are found worldwide in tropical and subtropical regions, except in Europe. Sea snakes occur mainly in the Indian Ocean and the southwest Pacific. However, the range of one species, Pelamis platura, extends across the Pacific to the coasts of Central and South America.

Venom

Many elapids are potentially deadly venomous snakes. Their venom is mainly neurotoxic, although many of them also possess several other types of toxins, including cardiotoxins and cytotoxins. This family has some members considered to be the world's most venomous land snakes based on the murine LD₅₀ of their venom, such as the inland taipan. Additionally, some large-sized elapids, such as the Asiatic king cobra, African black mamba, forest cobra, and Australasian coastal taipan, can inject a large quantity of venom during envenomation.

Elapids use their venom both to immobilize their prey and in self-defense.

Genera

Genus	Taxon author	Species	Subspecies*	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, the 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, the Philippines
Austrelaps	Worrell, 1963	3	0	copperheads	Australia (South Australia, New South Wales, Victoria, Tasmania)
Boulengerina	Dollo, 1886	2	1	water cobras	Cameroon, Gabon, the Democratic Republic of the Congo, Congo, the 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, the 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)
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, the 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 Islands
Enhydrina	Gray, 1849	2	0	beaked sea snakes	In the Persian Gulf (Oman, United Arab Emirates, etc.), south to the Seychelles and Madagascar, Southeast 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	A.M.C. Duméril, 1853	5	0	pale-naped snakes	Mainland Australia, southern New Guinea, Aru Islands
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	W. 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 Indo-Australian 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	W. Peters, 1864	1	0	bola	Fiji
Ophiophagus	Günther, 1864	1	0	king cobra	Bangladesh, Myanmar, Cambodia, China, India, Andaman Islands, Indonesia, Laos, Thailand, Vietnam, western Malaysia, the Philippines, Sri Lanka
Oxyuranus	Kinghorn, 1923	3	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, and 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	tree 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	F. 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
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	11	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

Taxonomy

The table above lists all of the elapid genera and no subfamilies. 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. Good molecular evidence via karyotyping, protein electrophoretic analysis, immunological distance, DNA sequence analysis, and so on, suggests reciprocal monophyly of two groups:

• African, Asian, and New World Elapinae
• Australasian and marine Hydrophiinae

Thus, the Australian terrestrial elapids are technically 'hydrophiines', although they are not sea snakes. It is believed that the Laticauda and the 'true sea snakes' evolved separately from 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 the group was moved to another family. In contrast to what is typical of 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 shouldhave been assigned to the Atractaspididae.

See also

• Elapidae by common name
• Elapidae by taxonomic synonyms
• List of snakes, overview of all snake families and genera