Everything about The Elapidae totally explained
The
Elapidae, or elapids, are a
family of
venomous snakes found in tropical and subtropical regions around the world, including the
Indian Ocean and the
Pacific. They are characterized by possessing a set of hollow, fixed fangs through which they inject venom, and come in a wide range of sizes, from only 18 cm (
Drysdalia) up to 6 m in length (
Ophiophagus). Currently, 61
genera that include 231
species are recognized.
Description
Outwardly,
terrestrial elapids look similar to the
colubridae: almost all have long and slender bodies with smooth scales, a head that's 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: for example 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 (for example
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, for example 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've 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 also lay their eggs (
oviparous). They having wide ventral scales, the tail isn't as well-developed for swimming, and their nostrils are separated by internasal scales. See also
Sea snake.
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 (for example
Acanthophis,
Oxyuranus) it's common for the fangs to pierce right through the intermandibular skin, which doesn't 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 fierce snake (
Oxyuranus microlepidotus), which is the most venomous land snake, and
Hydrophis belcheri, a sea snake and the most toxic venom of all snakes.
Genera
Further Information
Get more info on 'Elapidae'.
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