Sea snake
From Freepedia
Sea snakes of several different species belong to a group related to the cobras but aquatic rather than land dwelling. They are only moderately large, rarely exceeding 6 feet long, often with peculiarly small heads for their body. The body is compressed as an adaptation for swimming and the snakes are so thoroughly aquatic that they are either clumsy or helpless when brought ashore. Only genus Laticauda has the typical broad ventral scales of snakes, and it is often considered the least advanced of the sea snakes. Nevertheless, similar to cetaceans, their lungs still require them to surface occasionally to breathe.
Sea snakes are venomous. They have short hollow fangs near the front of the upper jaw, and the poison acts on the nervous system like that of the unrelated cobras. Unlike land snakes, however, sea snakes don't have an inclination to bite, and as such are not harmful unless abused. Sea snakes have a less efficient venom injection apparatus as compared to vipers or cobras. Anti-venom is not available commercially.
Sea snakes are confined to the tropical oceans, chiefly the Indian ocean and the western Pacific ocean. The yellow-bellied sea snake, Pelamydrus platurus, extends to the eastern Pacific. The olive sea snake, Aipysurus laevis, tends to live in reefs.
Sea kraits are a type of sea snake. Sea snakes are divided into two subfamilies, laticaudinae and hydrophiinae, with the former of the two distinguished from other sea snakes by the fact they are amphibious (lives on land and water), versus aquatic (never leaving the water). Sea kraits are ovoviviparous, returning to land to lay their eggs, versus other viviparous species that bear their young in the water (subfamily hydrophiinae, aquatic sea snakes). Amphibious sea kraits, members of subfamily laticaudinae, have specialized ventral scales for crawling on land. Unlike eels, sea snakes are reptiles and have scales. This one is about 18 inches (46 cm) in length.
All 50 or so species of sea snakes are venomous, and some are known to have venom ten times as strong as rattlesnake venom, making them among the most potentially dangerous of all animals. Fortunately for divers, they have short fangs and are usually quite docile; this one scarcely paid attention to my stalking, even as I placed my camera lens only about an inch from its head to get some photographs. It returned to the surface almost exactly every 15 minutes from a depth of about 35 feet, breaking the surface for only a split second to take a breath of air. On the bottom, it slowly crawled along, poking its head under coral crevices and under debris, foraging for small fish or perhaps eel prey. Most sea snakes feed this way, though at least one species, Pelamis platurus, is pelagic. A sea snake's paddle-shaped tail is useful for swimming, but otherwise these reptiles look very much like their land cousins, even down to the forked tongue it uses during its search.
Most cases of people being bitten by sea snakes involve fishermen bitten when sorting through a catch from a net. The venom is composed of powerful neurotoxins (affect nervous system) and sometimes myotoxins (affect skeletal muscles), with a fatal dose being about 1.5 milligrams. Most sea snakes can produce 10-15 mg of venom.
Identification: Laticauda colubrina (subfamily unknown) Common name: Banded Sea Krait or Yellow-lipped Sea Krait
Systematics
Literature
- Rasmussen AR (1997): Systematics of sea snakes; a critical review, Symp. Zool. Soc. London 70, 15-30
- Smith MA (1996): Monograph of the sea snakes (Hydrophiidae), British Museum of Natural History, London
- Voris HK (1977): A phylogeny of the sea snakes (Hydrophiidae), Fieldiana Zool. 70, 79-169
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