Elapidae
Elapidae is a family of venomous snakes characterized by hollow, permanently erect, relatively short fangs in the front of the mouth that channel venom into their prey. Elapids are 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 the family have a wide range of sizes, from the white-lipped snake to the king cobra. Most species have neurotoxins in their venom, while some may contain other toxic components in various proportions. The family includes 56 genera with some 360 species and some 170 subspecies.
Description
Appearance
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 include short and fat, rough-scaled, very broad-headed, cat-eyed, live-bearing, sluggish ambush predators with partly fragmented head shields.Sea snakes, 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, and they give birth to live young. The 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 and down to in length. Cobras, mambas, and taipans are mid- to large sized snakes which can reach or above. The king cobra is the world's longest venomous snake with a maximum length of and an average mass of.
Behavior
Most elapids are terrestrial, while some are strongly arboreal. Many species are more or less specialized burrowers in either humid or arid environments. Some species have very generalised diets, but many taxa have narrow prey preferences and correlated morphological specializations, for example feeding almost exclusively on other serpents. 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 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.
Dentition
All elapids have a pair of proteroglyphous fangs to inject venom from glands located towards the rear of the upper jaw. 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 and viperids. 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 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.Distribution
Terrestrial elapids are found worldwide in tropical and subtropical regions, mostly in the Southern Hemisphere. Most prefer humid tropical environments, and so 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 south-west 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.Venom
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. 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 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 commercial 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.Taxonomy
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, Micrurinae, Acanthophiinae, and the Laticaudinae. 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. regard it as a sister taxon to Atractaspis, which should have been assigned to the Atractaspidinae.
| Genus | Taxon author | Species | Subspecies* | Common name | Geographic range |
| Acanthophis | Daudin, 1803 | 7 | 0 | death adders | Australia, New Guinea, Indonesia |
| Aipysurus | Lacépède, 1804 | 7 | 1 | olive sea snakes | Timor Sea, South China Sea, Gulf of Thailand, and coasts of 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, Namibia, southern Angola, Botswana, Zimbabwe, Mozambique |
| Aspidomorphus | Fitzinger, 1843 | 3 | 3 | collared adders | New Guinea |
| Austrelaps | Worrell, 1963 | 3 | 0 | copperheads | Australia |
| 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, Myanmar, Nepal, Vietnam, Afghanistan, Pakistan, Sri Lanka, Bangladesh, Cambodia, Indonesia, Peninsular Malaysia, Singapore, Taiwan, Thailand |
| Cacophis | Günther, 1863 | 4 | 0 | rainforest crowned snakes | Australia |
| 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, 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 |
| Echiopsis | Fitzinger, 1843 | 1 | 0 | bardick | Southern Australia |
| Elapognathus | Boulenger, 1896 | 2 | 0 | southwestern grass snakes | Western Australia |
| Elapsoidea | Bocage, 1866 | 10 | 7 | African or venomous garter snakes | Sub-Saharan Africa |
| Emydocephalus | Krefft, 1869 | 3 | 0 | turtlehead sea snakes | The coasts of Timor, New Caledonia, 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, south to the Seychelles and Madagascar, Southeast Asian Sea, Australia, 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 |
| Hemibungarus | W. Peters, 1862 | 3 | 0 | Barred coral snakes | Philippines |
| Homoroselaps | Jan, 1858 | 2 | 0 | harlequin snakes | South Africa |
| Hoplocephalus | Wagler, 1830 | 3 | 0 | broad-headed snakes | Eastern Australia |
| 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. |
| Incongruelaps | 1 | 0 | Riversleigh, Australia | ||
| 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, Mexico |
| Micrurus | Wagler, 1824 | 80 | 54 | coral snakes | Southern North America, South America |
| Naja | Laurenti, 1768 | 36 | 3 | cobras | Africa, Asia |
| Neelaps | 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 |
| Parasuta | Worrell, 1961 | 6 | 0 | Australia | |
| Paroplocephalus | Keogh, Scott, and Scanlon, 2000 | 1 | 0 | Lake Cronin snake | Western Australia |
| Pseudechis | Wagler, 1830 | 7 | 0 | black snakes | 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 | 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 | 7 | 7 | Asia | |
| Suta | Worrell, 1961 | 4 | 0 | hooded snakes | Australia |
| Thalassophis | P. Schmidt, 1852 | 1 | 0 | anomalous sea snake | South Chinese Sea, Indian Ocean |
| Toxicocalamus | Boulenger, 1896 | 11 | 0 | New Guinea forest snakes | New Guinea |
| 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