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↓Yellow-bellied sea snake ( ) on a beach in Costa RicaKingdom:Phylum:Class:Order:Suborder:Family:Subfamily:, 1926Range of sea snakes shown in lime green, except the widespread, pelagicSea snakes, or coral reef snakes, are a subfamily of, the Hydrophiinae, that inhabit environments for most or all of their lives. Most are extensively adapted to a fully aquatic life and are unable to move on land, except for the genus, which has limited land movement.
They are found in warm coastal waters from the to the and are closely related to venomous terrestrial snakes in Australia.All sea snakes have paddle-like tails and many have laterally compressed bodies that give them an -like appearance. Unlike fish, they do not have and must surface regularly to breathe. Along with, they are among the most completely aquatic of all air-breathing. Among this group are species with some of the most potent venoms of all snakes. Some have gentle dispositions and bite only when provoked, but others are much more aggressive.
Currently, 17 are described as sea snakes, comprising 69. Contents.Description The majority of adult sea snakes species grow to between 120 and 150 cm (3.9 and 4.9 ft) in length, with the largest, reaching a maximum of 3 m (9.8 ft). Their eyes are relatively small with a round pupil and most have nostrils located dorsally.
The skulls do not differ significantly from those of terrestrial elapids, although their dentition is relatively primitive with short fangs and (with the exception of ) as many as 18 smaller teeth behind them on the maxilla. Yellow-lipped sea krait,Most sea snakes are completely aquatic and have adapted to sea environments in many ways, the most characteristic of which is a paddle-like tail that has improved their swimming ability. To a varying degree, the bodies of many species are laterally compressed, especially in the species.
This has often caused the to become reduced in size, even difficult to distinguish from the adjoining scales. Their lack of ventral scales means they have become virtually helpless on land, but as they live out their entire lifecycles at sea, they have no need to leave the water.The only that has retained the enlarged ventral scales is the sea kraits, with only five species. These snakes are considered to be more primitive, as they still spend much of their time on land, where their ventral scales afford them the necessary grip. Laticauda species are also the only sea snakes with, i.e., their nostrils are not located dorsally.Since a snake's tongue can fulfill its olfactory function more easily under water, its action is short compared to that of terrestrial snake species. Only the forked tips protrude from the mouth through a divided notch in the middle of the.
The nostrils have valves consisting of a specialized spongy tissue to exclude water, and the windpipe can be drawn up to where the short nasal passage opens into the roof of the mouth. This is an important adaptation for an animal that must surface to breathe, but may have its head partially submerged when doing so.
The lung has become very large and extends almost the entire length of the body, although the rear portion is thought to have developed to aid buoyancy rather than to exchange gases. The extended lung possibly also serves to store air for dives.Most species of the sea snakes are able to respire through the top of their skin. This is unusual for reptiles, because their skin is thick and scaly, but experiments with the black-and-yellow sea snake, (a species), have shown this species can satisfy about 25% of its oxygen requirements in this manner, which allows for prolonged dives. Sea Snake From Caspian Sea - Photographed in North of IranLike other land animals that have adapted to life in a marine environment, sea snakes ingest considerably more salt than their terrestrial relatives through their diets, and when seawater is inadvertently swallowed.
This meant they had to evolve a more effective means of regulating the salt concentration of their blood. In sea snakes, the posterior sublingual glands, located under and around the tongue sheath, evolved to allow them to expel salt with their tongue action.Scalation among sea snakes is highly variable.
As opposed to terrestrial snake species that have imbricate scales to protect against abrasion, the scales of most pelagic sea snakes do not overlap. Reef-dwelling species, such as, do have imbricate scales to protect against the sharp coral. The scales themselves may be smooth, spiny, or granular, the latter often looking like warts. Pelamis has body scales that are 'peg-like', while those on its tail are juxtaposed hexagonal plates. Sensory abilities , (tongue-flicking), and are important senses for terrestrial snakes, but these become distorted in water. The poor visibility, chemical dilution, and limitation of ground-borne vibrations under water suggest that sea snakes and sea kraits may have unique sensory abilities to compensate for the relative lack of other sensory cues.Very little is known about sea snake vision.
A study of of spine-bellied, and horned, sea snakes found three classes of all from. Despite the absence of rod cells in sea snake eyes, Simeos et al. Found from ( rh1) were still being suggesting that in sea snakes some cones may be transmuted rods. However, behavioural observations indicate that vision has a limited role for catching prey and mate selection, but sound (i.e. ) and may be important. One study identified small sensory organs on the head of similar to the mechanoreceptors in and aquatic snake that are used to sense the movement of fish prey. Westhoff et al.
Recorded to underwater in Lapemis curtus, which are sensitive enough to detect movement in prey, but were not as sensitive as systems. Similarly, vision appears to be of limited importance for finding mates. Shine experimented with applying skin secretions to snake-like objects to see if male turtle-headed sea snakes, are attracted to female pheromones. Shine found that although vision may be useful over short distances (. Olive sea snake,On land, their movements become very erratic. They crawl awkwardly in these situations and can become quite aggressive, striking wildly at anything that moves, although they are unable to coil and strike in the manner of terrestrial snakes.Sea snakes appear to be active both day and night. In the morning, and sometimes late in the afternoon, they can be seen at the surface basking in the sunlight, and they dive when disturbed.
They have been reported swimming at depths over 90 m (300 ft), and can remain submerged for as long as a few hours, possibly depending on temperature and degree of activity.Sea snakes have been sighted in huge numbers. For example, in 1932, a steamer in the, off the coast of, reported sighting 'millions' of, a relative of Pelamis; these reportedly formed a line of snakes 3 m (9.8 ft) wide and 100 km (62 mi) long. The cause of this phenomenon is unknown, although it likely has to do with reproduction.
They can sometimes be seen swimming in schools of several dozen, and many dead specimens have been found on beaches after typhoons. Ecology They feed on small fish and occasionally young octopus. They are often associated with the ( Platylepas ophiophila), which attaches to their skin. Reproduction Except for a single genus, all sea snakes are; the young are born alive in the water where they live their entire lives.
In some species, the young are quite large, up to half as long as the mother. The one exception is the genus Laticauda, which is; its five species all lay their eggs on land. Venom Like their relatives in the family Elapidae, the majority of the sea snakes are highly venomous; however, when bites occur, venom injection is rare, so envenomation symptoms usually seem nonexistent or trivial. For example, has a venom more potent than any terrestrial snake species in based on, but despite its abundance in the waters off its western coast, few human fatalities have been reported. The death of a trawler fisherman in Australian waters during 2018 was reported to be the region's first sea snake fatality since a pearl diver was killed in 1935.Bites in which envenomation does occur are usually painless and may not even be noticed when contact is made.
Teeth may remain in the wound. Usually, little or no swelling occurs, and rarely are any nearby affected. The most important symptoms are (rapid breakdown of skeletal muscle tissue) and paralysis.
Early symptoms include headache, a thick-feeling tongue, thirst, sweating, and vomiting. The venom is very slow acting and symptoms that happen from little as 30 minutes to several hours after the bite include generalized aching, stiffness, and tenderness of muscles all over the body. Passive stretching of the muscles is also painful, and, which is similar to, is common. This is followed later on by symptoms typical of other envenomations, a progressive flaccid paralysis, starting with and paralysis of voluntary muscles. Paralysis of muscles involved in swallowing and respiration can be fatal.
Taxonomy CladogramHydrophiinaesea kraitsLaticaudasea snakesEmydocephalusAipysurusHydrelapsHydrophisCladogram showing the basic evolutionary relationships among sea snakes, sea kraits and other venomous terrestrial snakes. Sea kraits are more closely related to the Asiatic elapids such as cobras, in contrast sea snakes form a monophyletic group that are more closely related to Australian elapids.Sea snakes were at first regarded as a unified and separate family, the Hydrophiidae, that later came to comprise two subfamilies: the Hydrophiinae, or true/aquatic sea snakes (now 16 genera with 57 species), and the more primitive Laticaudinae, or sea kraits (one genus, Laticauda, with five species). Eventually, as just how closely related the sea snakes are to the elapids became clear, the taxonomic situation became less well-defined. Some taxonomists responded by moving the sea snakes to the Elapidae, thereby creating the subfamilies Elapinae, Hydrophiinae, and Laticaudinae, although the latter may be omitted if Laticauda is included in the Hydrophiinae. No one has yet been able to convincingly work out the relationships between the various elapid subgroups, and the situation is still unclear. Therefore, others opted to either continue to work with the older traditional arrangements, if only for practical reasons, or to lump all of the genera together in the Elapidae, with no taxonomic subdivisions, to reflect the work that remains to be done. At best, sea snakes make difficult captives.
Ditmars (1933) described them as nervous and delicate captives that usually refuse to eat, preferring only to hide in the darkest corner of the tank. Over 50 years later, Mehrtens (1987) wrote, although they were rarely displayed in Western zoological parks, some species were regularly on display in Japanese aquariums. Available food supply limits the number of species that can be kept in captivity, since some have diets that are too specialized. Also, some species appear intolerant of handling, or even being removed from the water.
Regarding their requirements in captivity, the species need to be able to exit the water somewhere at about 29 °C, along with a submerged shelter. Species that have done relatively well in captivity include the ringed sea snake, which feeds on and in particular. Has done especially well in captivity, accepting small fish, including.
However, care has to be taken to house them in round or oval tanks, or in rectangular tanks with corners that are well-rounded, to prevent the snakes from damaging their snouts by swimming into the sides. Conservation status Most sea snakes are not on the protection lists, however, one species, is classified as vulnerable. Several species of are listed with conservation status of greater concern, the Timor species is known to be endangered, and two others found in seas north of Australia, the leaf-scaled and short-nosed, are classified as according to the Red List of Threatened Species. See also.References.
Graham JB, Lowell WR, Rubinoff I, Motta J. Surface and subsurface swimming of the sea snake Pelamis platurus. At the Journal of Experimental Biology.
Accessed 7 August 2007. Rasmussen AR. Systematics of sea snakes; a critical review. London 70, 15-30. Smith MA.
Monograph of the sea snakes (Hydrophiidae). British Museum of Natural History, London. Voris HK. A phylogeny of the sea snakes (Hydrophiidae).
Fieldiana Zool. 70, 79-169. Whitaker R. Common Indian Snakes: A Field Guide. Macmillan India Limited.External links has information related to. at. Accessed 6 August 2007.
Indian Snakes A Field Guide
first hand account of scuba divers interacting with sea snakes at the Indonesian volcano Gunung Api, June 2009. Alexis Gillham, Townsville Bulletin, 8 November 2010. Accessed 8 November 2010.