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

Elapidae (Greek ἔλλοψ éllops, "sea-fish") ^[1] is 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 exist in a wide range of sizes, from 18-cm species of Drysdalia to the 5.6-m king cobra, and are characterized by hollow, fixed fangs through which they inject venom. Currently, 325 species in 61 genera are recognized.^[2]

Description[link]

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 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, 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, etc.

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, 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, the tail is not as well-developed for swimming, and their nostrils are separated by internasal scales.

Dentition[link]

The fangs, which are enlarged and hollow, are the first two teeth on each maxillary bone, and 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, 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.

Geographic range[link]

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.^[3]

Venom[link]

All elapids are venomous snakes which are potentially deadly. Their venom is mainly neurotoxic, although many also possess several other toxins, including cardiotoxin and cytotoxin. Some large-sized elapids, such as the Asiatic king cobra, African black mamba, Egyptian cobra 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[link]

* Not including the nominate subspecies

Taxonomy[link]

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. Now, good molecular evidence via karyotyping and protein electrophoretic analysis, immunological distance, DNA sequence analysis etc. exists 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.^[7]

^[8]

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.

See also[link]

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

References[link]

Wikimedia Commons has media related to: Elapidae