Difference between revisions of "Elapidae" - New World Encyclopedia
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− | '''Elapidae''', whose members are known as '''elapids''', is a [[family]] of [[venomous snake]]s characterized by a single pair of hollow, permanently erect, relatively short fangs in the front of the mouth that channel venom into the prey. This proteroglyphic dentition, meaning "fixed front fangs," is a major distinguishing characteristic from the other major family of venomous snakes, Viperidae, whose venom delivery system involves two, long, hollow, venom-injecting fangs that | + | '''Elapidae''', whose members are known as '''elapids''', is a [[family]] of [[venomous snake]]s characterized by a single pair of hollow, permanently erect, relatively short fangs in the front of the mouth that channel venom into the prey. This proteroglyphic dentition, meaning "fixed front fangs," is a major distinguishing characteristic from the other major family of venomous snakes, Viperidae, whose venom delivery system involves two, long, hollow, venom-injecting fangs that fold back against the roof of the mouth when the mouth is closed (solenoglyphic dentition, or "movable front fangs"). |
Elapids are a diverse group of more than 300 species placed in about 60 [[genus|genera]] (Keogh 2004), including species that live in terrestrial, arboreal, and marine environments. They are found in tropical and subtropical regions around the world, including the Americas, Africa, Asia, Australia, and the [[Indian Ocean|Indian]] and [[Pacific Ocean|Pacific]] Oceans. Well-known members include [[cobra]]s, [[mamba]]s, [[coral snake]]s, death adders, and sea snakes. | Elapids are a diverse group of more than 300 species placed in about 60 [[genus|genera]] (Keogh 2004), including species that live in terrestrial, arboreal, and marine environments. They are found in tropical and subtropical regions around the world, including the Americas, Africa, Asia, Australia, and the [[Indian Ocean|Indian]] and [[Pacific Ocean|Pacific]] Oceans. Well-known members include [[cobra]]s, [[mamba]]s, [[coral snake]]s, death adders, and sea snakes. |
Revision as of 01:16, 28 July 2008
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Egyptian cobra, Naja haje
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Elapidae, whose members are known as elapids, is a family of venomous snakes characterized by a single pair of hollow, permanently erect, relatively short fangs in the front of the mouth that channel venom into the prey. This proteroglyphic dentition, meaning "fixed front fangs," is a major distinguishing characteristic from the other major family of venomous snakes, Viperidae, whose venom delivery system involves two, long, hollow, venom-injecting fangs that fold back against the roof of the mouth when the mouth is closed (solenoglyphic dentition, or "movable front fangs").
Elapids are a diverse group of more than 300 species placed in about 60 genera (Keogh 2004), including species that live in terrestrial, arboreal, and marine environments. They are found in tropical and subtropical regions around the world, including the Americas, Africa, Asia, Australia, and the Indian and Pacific Oceans. Well-known members include cobras, mambas, coral snakes, death adders, and sea snakes.
Description
They come in a wide range of sizes, from only 18 cm (Drysdalia) up to 6 m in length (Ophiophagus).
Outwardly, terrestrial elapids look similar to the 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: 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, Vermicella) in either humid or arid environments. Some species have very generalised diets but many taxa have narrow prey preferences and correlated morphological specialisations, e.g. for feeding on other snakes, elongate burrowing lizards, squamate eggs, mammals, birds, frogs, fish, etc.
Sea snakes, which are also elapids, 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 (Laticauda sp. ), are the least well-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.
All elapids have a pair of proteroglyphous fangs that are used to inject venom from glands located towards the rear of the upper jaws. The fangs are the first two teeth on each maxillary bone, which are enlarged and hollow, and usually only one is in place on each side at any time. The maxilla is intermediate in 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; in the longest-fanged elapids (e.g. Acanthophis, Oxyuranus) it is common for the fangs to pierce right through the intermandibular skin, which does not seem to endanger the snake. The fangs are usually below the front edge of the eye and are angled backwards; due to this construction, most elapids must actually bite in order to envenomate. This action is therefore not as quick as with the viperids, that can envenomate with only a quick, stabbing motion. Some elapids (Acanthophis, Oxyuranus, and especially Dendroaspis) have long fangs on quite mobile maxillae (the prefrontal and ectopterygoid contacts are nearly as close together as in viperids), and can therefore make very fast stabbing strikes like viperids. A few species are capable of spraying their venom from forward facing holes at the tips of their fangs as a means of defense. Elapids use their venom both to immobilize their prey and in self-defense.
Venom
All elapids are venomous and many are potentially deadly. The venoms are mostly neurotoxic and are considered more dangerous than the mainly proteolytic viper venoms. Members include the black mamba (Dendroaspis polylepis), a species many regard as the world's most dangerous snake, the inland taipan (Oxyuranus microlepidotus), which is the most venomous land snake, and Hydrophis belcheri, a sea snake and the most toxic venom of all snakes.
Genera
Currently, 61 genera that include 231 species are recognized.[1]
Genus[1] | Authority[1] | Species[1] | Subsp.*[1] | Common name | Geographic range[2] |
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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 (North Territory, Queensland, West 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 | 0 | New Guinea. | |
Astrotia | Fischer, 1855 | 1 | 0 | Stoke's 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). |
Elapognathus | Boulenger, 1896 | 2 | 0 | Southwestern grass snakes | Western Australia. |
Elapsoidea | Bocage, 1866 | 10 | 7 | African or Venomous Garter snakes (unrelated to North American non-venomous Garter Snakes) | 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 (North Territory, Queensland, West 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 | North-western 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.[3] |
Kerilia | Gray, 1849 | 1 | 0 | Jerdon's sea snake | Southeast Asian waters.[3] |
Kolpophis | M.A. Smith, 1926 | 1 | 0 | Bighead sea snake | Indian Ocean.[3] |
Lapemis | Gray, 1835 | 1 | 1 | Shaw's sea snake | Persian Gulf to Indian Ocean, South China Sea, Indo-Australian archipelago and the western Pacific.[3] |
Laticauda | Laurenti, 1768 | 5 | 0 | Sea kraits | Southeast Asian and Indoaustralian waters. |
Leptomicrurus | 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 | Schmidt, 1928 | 1 | 2 | Western coral snakes | USA (Arizona, SW New Mexico), Mexico (Sonora, Sinaloa). |
Micrurus | Wagler, 1824 | 69 | 54 | Coral snakes | southern North America, South America. |
Naja | Laurenti, 1768 | 20 | 5 | 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 and Scanlon, 2000 | 1 | 0 | Lake Cronin snake | Western Australia. |
Pelamis | Daudin, 1803 | 1 | 0 | Yellow-bellied sea snake | Indian and Pacific Oceans. |
Praescutata | Wall, 1921 | 1 | 0 | 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 | Slowinski et al., 2001 | 5 | 4 | 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 | 1 | 0 | Black desert cobra | Egypt, Israel, Lebanon, Syria, Jordan, Iraq, Iran, Kuwait, Saudi Arabia. |
* Not including the nominate subspecies (typical form).
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. There is now good molecular evidence 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.[4]
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.
ReferencesISBN links support NWE through referral fees
- ↑ 1.0 1.1 1.2 1.3 1.4 Elapidae (TSN 174348). Integrated Taxonomic Information System. Accessed on 27 November 2006.
- ↑ Template:NRDB family
- ↑ 3.0 3.1 3.2 3.3 The Hydrophiidae at Cyberlizard's home pages. Accessed [12 August] [2007].
- ↑ Slowinski, J. B. and Keogh J. S. (April 2000). Phylogenetic Relationships of Elapid Snakes Based on Cytochrome b mtDNA Sequences. Molecular Phylogenetics and Evolution 15 (1): 157–164.
- Integrated Taxonomic Information System (ITIS). 2004. Elapidae F. Boie, 1827 ITIS Taxonomic Serial No.: 174348. Retrieved July 26, 2008.
- McDiarmid, R. W., J. A. Campbell, and T. Touré. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, Vol. 1. Herpetologists' League. ISBN 1893777014.
- Keogh, J. S. 2004. Elapidae. In B. Grzimek, D. G. Kleiman, V. Geist, and M. C. McDade, eds., Grzimek's Animal Life Encyclopedia. Detroit: Thomson-Gale. ISBN 0787657883.
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