Elapidae (, commonly known as elapids ; grc, ἔλλοψ ''éllops'' "sea-fish") is a
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
of
snake
Snakes are elongated, Limbless vertebrate, limbless, carnivore, carnivorous reptiles of the suborder Serpentes . Like all other Squamata, squamates, snakes are ectothermic, amniote vertebrates covered in overlapping Scale (zoology), scales. Ma ...
s characterized by their permanently erect fangs at the front of the mouth. Most elapids are
venomous
Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...
, with the exception of the genus
Emydocephalus
''Emydocephalus'' is a genus of sea snakes, also known as turtle-headed sea snakes, in the family Elapidae. Unlike most sea snakes, all species of ''Emydocephalus'', have an absence of teeth on their dentary and palatine bones, and lack venom, m ...
. Many members of this family exhibit a
threat display
Deimatic behaviour or startle display means any pattern of bluffing behaviour in an animal that lacks strong defences, such as suddenly displaying conspicuous eyespots, to scare off or momentarily distract a predator, thus giving the prey anima ...
of rearing upwards while spreading out a neck flap. Elapids are endemic to
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
and
subtropical
The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...
regions around the world, with terrestrial forms in
Asia
Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
,
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
,
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
, and the
Americas
The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World.
Along with th ...
and marine forms in the
Pacific
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
and
Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...
s. Members of the family have a wide range of sizes, from the
white-lipped snake
The white-lipped snake (''Drysdalia coronoides'') is a small species of venomous snake in the family Elapidae. The species is endemic to south-eastern mainland Australia and Tasmania.
Description
It is the smallest of three species of snake f ...
to the
king cobra. Most species have
neurotoxic
Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specificall ...
venom which is channeled by their hollow fangs, and some may contain other toxic components in various proportions. The family includes 55
genera
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
with some 360
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
and over 170 subspecies.
Description
Terrestrial
Terrestrial refers to things related to land or the planet Earth.
Terrestrial may also refer to:
* Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...
elapids look similar to the
Colubridae
Colubridae (, commonly known as colubrids , from la, coluber, 'snake') is a family of snakes. With 249 genera, it is the largest snake family. The earliest species of the family date back to the Oligocene epoch. Colubrid snakes are found on ever ...
; 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
Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and ...
. Exceptions to all these generalizations occur: e.g. the death adders (''
Acanthophis
''Acanthophis'' is a genus of elapid snakes. Commonly called ''death adders'', they are native to Australia, New Guinea and nearby islands, and are among the most venomous snakes in the world. Despite their common name, they are not adder ...
'') which have similarities to the
viper
The Viperidae (vipers) are a family of snakes found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, and various other isolated islands. They are venomous and have long (relative to non-vipers), hinged fangs tha ...
s: short and fat bodies, rough-scaled, very broad-headed, cat-eyed, live-bearing, sluggish ambush predators with partly fragmented head shields.
Sea snakes (the
Hydrophiinae
Hydrophiinae is a subfamily of venomous snakes in the family Elapidae. It contains most sea snakes and many genera of venomous land snakes found in Australasia, such as the taipans (''Oxyuranus''), tiger snakes (''Notechis''), brown 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
In snakes, the ventral scales or gastrosteges are the enlarged and transversely elongated scales that extend down the underside of the body from the neck to the anal scale. When counting them, the first is the anteriormost ventral scale that conta ...
are much reduced in size, their nostrils are located dorsally (no
internasal scales
In snakes, the internasal scales are those on top of the head between the scales that surround the nostrils. Wright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: Comstock Publishing Associates. (7t ...
), and they give birth to live young (
viviparity
Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the m ...
). The reduction in ventral scaling has greatly diminished their terrestrial mobility, but aids in swimming.
Members of this family have a wide range of sizes. ''
Drysdalia
''Drysdalia'' is a genus of snakes, commonly known as crowned snakes, belonging to the family Elapidae. The three species in this genus are venomous snakes, but not considered deadly.
Geographic range
Species of the genus ''Drysdalia'' are end ...
'' species are small serpents typically and down to in length.
Cobras,
mamba
Mambas are fast moving highly venomous snakes of the genus ''Dendroaspis'' (which literally means "tree asp") in the family Elapidae. Four extant species are recognised currently; three of those four species are essentially arboreal and green ...
s, and
taipan
Taipans are snakes of the genus ''Oxyuranus'' in the elapid family. They are large, fast-moving, highly venomous, and endemic to Australia and New Guinea. Three species are recognised, one of which, the coastal taipan, has two subspecies. Taipan ...
s 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 .
Dentition
![Ophiophagus hannah skull](https://upload.wikimedia.org/wikipedia/commons/8/87/Ophiophagus_hannah_skull.jpg)
All elapids have a pair of
proteroglyphous
A snake skeleton consists primarily of the skull, vertebrae, and ribs, with only vestigial remnants of the limbs.
Skull
The skull of a snake is a very complex structure, with numerous joints to allow the snake to swallow prey far larger than ...
fangs to inject
venom
Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...
from glands located towards the rear of the upper jaw (except for the genus
Emydocephalus
''Emydocephalus'' is a genus of sea snakes, also known as turtle-headed sea snakes, in the family Elapidae. Unlike most sea snakes, all species of ''Emydocephalus'', have an absence of teeth on their dentary and palatine bones, and lack venom, m ...
, in which fangs as present a vestigal feature but without venom production, as they have specialized toward a
fish egg
An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...
diet). The fangs, which are enlarged and hollow, are the first two teeth on each
maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...
ry 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
The Viperidae (vipers) are a family of snakes found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, and various other isolated islands. They are venomous and have long (relative to non-vipers), hinged fangs t ...
(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 cobra
A spitting cobra is any of several species of cobras that can defensively spray a toxic secretion - functioning as both a venom (that can be injected via a wound) and a toxungen (that can be sprayed on the target surface) - from their fangs in ...
s.
Behavior
Most elapids are
terrestrial
Terrestrial refers to things related to land or the planet Earth.
Terrestrial may also refer to:
* Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...
, while some are strongly arboreal (African ''
Pseudohaje
''Pseudohaje'' is a genus of Venomous snake, venomous African Elapidae, elapid snakes, commonly called tree cobras or forest cobras because of their arboreal lifestyle. Their ability to produce a hood is limited to a slight flattening of the ne ...
'' and ''
Dendroaspis
Mambas are fast moving highly venomous snakes of the genus ''Dendroaspis'' (which literally means "tree asp") in the family Elapidae. Four extant species are recognised currently; three of those four species are essentially arboreal and green ...
'', Australian ''
Hoplocephalus''). Many species are more or less specialized burrowers (e.g. ''
Ogmodon
The Fiji snake (''Ogmodon vitianus''), also known as the Fiji cobra or Bolo snake, is a species of snake in the family Elapidae. It is monotypic within the genus ''Ogmodon''. It is endemic to Fiji, found only on the island of Viti Levu
Viti Le ...
'', ''
Parapistocalamus'', ''
Simoselaps
''Simoselaps'', or Australian coral snakes, is a genus composed of 12 species of venomous elapid snakes.
Geographic range
Species of the genus ''Simoselaps'' are found throughout Australia.
Description
Australian coral snakes are small snakes. ...
'', ''
Toxicocalamus
''Toxicocalamus'' is a genus of snakes in the family Elapidae. The genus is endemic to New Guinea.
Description
Most species of ''Toxicocalamus'' are relatively small, the largest specimen known being the holotype of the recently described ''To ...
'', 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
''Bungarus'' is a genus of venomous elapid snakes, the kraits ("krait" is pronounced , rhyming with "kite"), found in South and Southeast Asia. The genus ''Bungarus'' has 16 species.
Distribution
Kraits are found in tropical Asia, from near Ir ...
). 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
The yellow-bellied sea snake (''Hydrophis platurus'') is a venomous species of snake from the subfamily Hydrophiinae (the sea snakes) found in tropical oceanic waters around the world except for the Atlantic Ocean. For many years, it was place ...
'', 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.
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
Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specificall ...
for immobilizing prey and defense. The main group of toxins are
PLA2
The enzyme phospholipase A2 (EC 3.1.1.4, PLA2, systematic name phosphatidylcholine 2-acylhydrolase) catalyse the cleavage of fatty acids in position 2 of phospholipids, hydrolyzing the bond between the second fatty acid “tail” and the glycer ...
and
Three-finger toxin
Three-finger toxins (abbreviated 3FTx) are a protein superfamily of small toxin proteins found in the venom of snakes. Three-finger toxins are in turn members of a larger superfamily of three-finger protein domains which includes non-toxic prote ...
s (3FTx). Other toxic components in some species comprise
cardiotoxins and
cytotoxins
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa'').
Cell physiology
Treating cell ...
, which cause heart dysfunctions and cellular damage, respectively. Cobra venom also contains
hemotoxin
Hemotoxins, haemotoxins or hematotoxins are toxins that destroy red blood cells, disrupt blood clotting, and/or cause organ degeneration and generalized tissue damage. The term ''hemotoxin'' is to some degree a misnomer since toxins that damage ...
s which clot or solidify blood. All members are venomous to varying extents, and some are considered among the world's most venomous snakes based upon their
murine
The Old World rats and mice, part of the subfamily Murinae in the family Muridae, comprise at least 519 species. Members of this subfamily are called murines. In terms of species richness, this subfamily is larger than all mammal families excep ...
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
Envenomation is the process by which venom is injected by the bite or sting of a venomous animal.
Many kinds of animals, including mammals (e.g., the northern short-tailed shrew, ''Blarina brevicauda''), reptiles (e.g., the king cobra), spider ...
and/or striking at a high position proximal to the victim's
brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...
, which is vulnerable to neurotoxicity.
Antivenom
Antivenom, also known as antivenin, venom antiserum, and antivenom immunoglobulin, is a specific treatment for envenomation. It is composed of antibodies and used to treat certain venomous bites and stings. Antivenoms are recommended only if th ...
is promptly required to be administrated if bitten by any elapids. Specific antivenoms are the only cure to treat elapidae bites. There are commercial monovalent and polyvalent antivenoms for cobras, mambas, and some other important elapids. Recently, experimental antivenoms based on recombinant toxins have shown that is feasible to create antivenoms with a wide spectrum of coverage.
Venom of spitting cobras is more cytotoxic rather than neurotoxic. It damages local cells, especially those in eyes, which are deliberately targeted by the snakes. The venom may cause intense pain on contact with the eye and may lead to blindness. It is not lethal on skin if no wound provides any chance for the toxins to enter the
bloodstream
The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
.
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 (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 monophyly of two groups: African, Asian, and New World Elapinae versus Australasian and marine
Hydrophiinae
Hydrophiinae is a subfamily of venomous snakes in the family Elapidae. It contains most sea snakes and many genera of venomous land snakes found in Australasia, such as the taipans (''Oxyuranus''), tiger snakes (''Notechis''), brown snakes (' ...
. The Australian terrestrial elapids are technically 'hydrophiines', although they are not sea snakes. It is believed that the ''
Laticauda
Sea kraits are a genus of venomous elapid sea snakes (subfamily: Laticaudinae), ''Laticauda''. They are semiaquatic, and retain the wide ventral scales typical of terrestrial snakes for moving on land, but also have paddle-shaped tails for swimmi ...
'' 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
In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name.
Zoological nomenclature
According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal f ...
for the Elapidae was originally ''Elaps'', but the group was moved to another family. In contrast to what is typical of
botany
Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek w ...
, the family Elapidae was not renamed. In the meantime, ''Elaps'' was renamed ''
Homoroselaps
''Homoroselaps'' is a genus of venomous snakes of the family Atractaspididae..
Species
* ''Homoroselaps dorsalis'' (Smith, 1849)
* ''Homoroselaps lacteus
''Homoroselaps lacteus'', also known as the spotted harlequin snake, is a species of a ...
'' 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.
''* Not including the nominate subspecies''
Conservation
With the dangers the taxa presents given their venomous nature it is very difficult for activists and conservationists alike to get species on protection lists such as the IUCN red-list and CITES Apenndix lists. Some of the protected species are:
* Vulnerable:
** ''
Ophiophagus hannah'' (King cobra)
** ''
Austrelaps labialis'' (Pygmy copperhead)
** ''
Denisonia maculate'' (Ornamental snake)
** ''
Echiopsis atriceps'' (Lake Cronin snake)
** ''
E. curta'' (Bardick)
** ''
Furina dunmalli
Dunmall's snake (''Furina dunmalli'') is a species of venomous snake in the family Elapidae. The species is endemic to Australia.
Etymology
The specific name, ''dunmalli'', is in honor of William "Bill" Dunmall, who collected the type specimen. ...
'' (Dunmall's snake)
** ''
Hoplocephalus bungaroides
The broad-headed snake (''Hoplocephalus bungaroides'') is a species of venomous snake in the family Elapidae. The species is restricted to the Sydney Basin in New South Wales, Australia. It is one of three snakes in the genus '' Hoplocephalus'' ...
'' (Broad-headed snake)
** ''
Ogmodon vitianus'' (Fiji snake)
* Lower Risk/Near threatened:
** ''
Elapognathus minor
The short-nosed snake (''Elapognathus minor'') is a species of venomous snake in the family Elapidae. The species is endemic to Australia. Short-nosed snakes are endemic to swamplands and coastlands in the southwest of Western Australia, where the ...
'' (Short-nosed snake)
** ''
Simoselaps calonotus
''Neelaps calonotos'', also known commonly as the black-striped burrowing snake, the black-striped snake, and the western black-striped snake, is a species of venomous burrowing snake endemic to Australia. The specific epithet ''calonotos'' ...
'' (Black-striped snake)
This however doesn't touch the number of elapidae that are under threat, for instance 9 % of elapid sea snakes are threatened with another 6 % near-threatened.
[ Eifes, C.T. & Livingstone 2013.] A rather large road block that stands in the way of more species being put under protection is lack of knowledge of the taxa; many known species have little research done on their behaviors or actual population as they live in very remote areas or live in habitats that are so vast its nearly impossible to conduct population studies, like the sea snakes.
See also
*
List of snake genera, overview of all snake families and genera
Explanatory notes
References
Further reading
*
External links
{{Authority control
Venomous snakes
Snake families
Taxa named by Friedrich Boie
Endemic fauna of Saudi Arabia