|King cobra (Ophiophagus hannah), the world's longest venomous snake|
F. Boie, 1827
|Subfamilies and genera[a]|
Elapidae (/ɪˈlæpɪdiː/, commonly known as elapids /ˈɛləpɪdz/; Ancient Greek: ἔλλοψ éllops "sea-fish") is a family of venomous snakes endemic to tropical and subtropical regions around the world, with terrestrial forms in Asia, Australia, Africa, and the Americas alongside marine forms in the Pacific and Indian Oceans. Members of this family have a wide range of sizes, from the smallest 18 cm (7.1 in) white-lipped snake to the longest 5.85 m (19.2 ft) king cobra, all of which, however, have fixed hollow fangs for venom injection to subdue prey and defend themselves. Most species have neurotoxins in their venom, while some may contain other toxic components with various proportions. This family includes 56 genera with some 360 species and some 170 subspecies.
Terrestrial elapids look similar to the Colubridae; almost all have long, 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.
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 (viviparity). This reduction in ventral scaling has greatly diminished their land mobility, but aids in swimming.
Members of this family have a wide range of sizes. Drysdalia species are small serpents typically 50 cm (20 in) and down to 18 cm (7.1 in) in length. Cobras, mambas, and taipans are mid- to large sized snakes which can reach 2 m (6 ft 7 in) or above. The king cobra is the world's longest venomous snake with a maximum length of 5.85 m (19.2 ft) and an average mass of 6 kg (13 lb).
Most elapids are terrestrial, while some are strongly arboreal (African Pseudohaje and Dendroaspis, Australian Hoplocephalus). Many species are more or less specialized burrowers (e.g. Ogmodon, Parapistocalamus, Simoselaps, Toxicocalamus, and Vermicella) in either humid or arid environments. Some species have very generalised diets (euryphagy), but many taxa have narrow prey preferences (stenophagy) and correlated morphological specializations, for example feeding almost exclusively on other serpents (especially the king cobra and kraits). Elapids may display a series of warning signs if provoked, either obviously or subtly. Cobras and mambas lift their inferior body parts, expand hoods, and hiss if threatened; kraits often curl up before hiding their heads down their bodies.
In general, sea snakes are able to respire through their skin; experiments with the yellow-bellied sea snake, Hydrophis 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. Their bodies are less compressed laterally, and they have thicker bodies and ventral scaling. Because of this, they are capable of some land movement. They spend much of their time on land, where they lay their eggs and digest prey.
All elapids have a pair of proteroglyphous fangs to inject venom from glands located towards the rear of the upper jaws. 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, taipan, mamba, and king cobra) 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 in their fangs for defense as exemplified by spitting cobras. Venom may cause intense pain if not blindness upon contact with eyes.
Terrestrial elapids are found worldwide in tropical and subtropical regions, mostly in the Southern Hemisphere. Most prefer humid tropical environments, and as such are not found in the Sahara or Middle East, although some can be found in Mexican and Australian deserts. Sea snakes occur mainly in the Indian Ocean and the southwest Pacific. They occupy coastal waters and shallows, and are common in coral reefs. However, the range of Hydrophis platurus extends across the Pacific to the coasts of Central and South America.
Venoms of species in the Elapidae are mainly neurotoxic for immobilizing prey and defense.The main group of toxins are PLA2 and Three finger toxins (3FTx). Other toxic components in some species comprise cardiotoxins and cytotoxins, which cause heart dysfunctions and cellular damage, respectively. Bites from all the members of this family are potentially fatal, some of which are even considered to be the world's most venomous snakes based upon their murine LD50 values, such as the taipans. Large species, mambas and cobras included, are dangerous for their capability of injecting high quantities of venom upon single envenomation and/or striking at a high position proximal to the victim's brain, which is vulnerable to neurotoxicity. Antivenom is promptly required to be administrated if bitten by any elapids. Venom of spitting cobras is more cytotoxic rather than neurotoxic. It damages local cells, especially those in eyes, which are purposely targeted by the snakes. The venom may cause intense pain if not blindness upon contact with eyes. It is not lethal on skin if no wound provides any chance for the toxins to make contact with the blood. Specific antivenoms are the only cure to treat elapidae bites. There are comercial monovalent and polyvalent antivenoms for Mambas, Cobras, Najas, and some other important elapids. Recently, experimental antivenoms based on recombinant toxins have a shown that is feasible to create antivenoms with a wide spectrum of coverage.
The table below lists out 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. Molecular evidence via techniques like karyotyping, protein electrophoretic analyses, immunological distance and DNA sequencing, suggests reciprocal monopholoy of two groups: African, Asian, and New World Elapinae versus Australasian and marine Hydrophiinae. 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 family Elapidae 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 have been assigned to the Atractaspidinae.
|Acanthophis||Daudin, 1803||7||0||death adders||Australia, New Guinea, Indonesia (Seram Island 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|
|Antaioserpens||Wells & Wellington, 1985||2||0||burrowing snakes||Australia|
|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|
|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|
|Brachyurophis||Günther, 1863||7||0||shovel-nosed snakes||Australia|
|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|
|Cryptophis||Worrell, 1961||5||0||Australia and Papua New Guinea|
|Demansia||Gray, 1842||9||2||whipsnakes||New Guinea, continental Australia|
|Dendroaspis||Schlegel, 1848||4||1||mambas||Sub-Saharan Africa|
|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 harmless to humans)||Sub-Saharan Africa|
|Emydocephalus||Krefft, 1869||3||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||rinkhals/ring-necked spitting cobra||South Africa, Zimbabwe, Lesotho, Swaziland|
|Hemiaspis||Fitzinger, 1861||2||0||swamp snakes||Eastern Australia (New South Wales, Queensland)|
|Hemibungarus||W. Peters, 1862||3||0||Barred coral snakes||Philippines (Luzon, Panay, Negros, Cebu, Polillo is.)|
|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.|
|Laticauda||Laurenti, 1768||5||0||sea kraits||Southeast Asian and Indo-Australian waters|
|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||United States (Arizona, southwestern New Mexico), Mexico (Sonora, Sinaloa)|
|Micrurus||Wagler, 1824||80||54||coral snakes||Southern North America, South America|
|Naja||Laurenti, 1768||23||3||cobras||Africa, Asia|
|Neelaps||(Duméril, Bibron & Duméril, 1854)||1||0||Australia|
|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|
|Oxyuranus||Kinghorn, 1923||3||2||taipans||Australia, New Guinea|
|Parahydrophis||Burger & Natsuno, 1974||1||0||Northern mangrove sea snake||Northern Australia, southern New Guinea|
|Parapistocalamus||Roux, 1934||1||0||Hediger's snake||Bougainville Island, Solomons|
|Paroplocephalus||Keogh, Scott, and Scanlon, 2000||1||0||Lake Cronin snake||Western Australia|
|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||1||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||Slowinski, Boundy, & Lawson, 2001||5||7||Asia|
|Suta||Worrell, 1961||4||0||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||6||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
- List of snake genera, overview of all snake families and genera
- The elapids in the past were considered to have two subfamilies–the Elapinae made of terrestrial species and Hydrophiinae made of the marine species. In 1997, Slowinski, Knight and Rooney found in their phylogenetic analysis using amino acid sequences from venom proteins, that the Australasian terrestrial species nested within Hydrophiinae. This led to removing the Australasian terrestrial species and placing them in the Hydrophiinae. This has been support in subsequent recent genomic analyses, though these same studies also found the subfamily Elapinae to be paraphyletic in respect to the Hydrophiinae. These studies have found coral snakes, cobras and mambas, kraits, and African gartersnakes forming successive outgroups to Hydrophiinae. Since there are available clade names for these groups (with the exception of Elapsoidea), it is ideal to bring back the subfamilies Calliophiinae, Micrurinae, Najinae, and Bungarinae.
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