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By Anders Nielsen, Ph.d.
Genetically, sea snakes and cobras are rather similar. However, sea snakes are aquatic, unlike their remote terrestrial relatives. When transported ashore, sea snakes are rather uncomfortable, stressing how well adapted they are to the aquatic environment.
It seldom exceeds six feet, and its head is relatively small compared to other species. Its head is flattened to offer as little hydraulic resistance as possible when in its aquatic environment. Sea snakes are divided into two subfamilies, the Laticaudinae and Hydrophiinae.
Members of the former group are amphibious. They are called sea kraits and true sea snakes respectively.
Sea snakes primarily feed on fish, and apparently there is a difference in diet between males and females. A study1 showed that male sea snakes had a more varied diet than female sea snakes. Empirically, the study showed that male sea snakes had an average of 16 different species in their stomachs while females had only six on average.
Sea snakes are confined to relatively temperate aquatic environments like those found in the Tropical Ocean, the Indian Ocean, and the western parts of the Pacific Ocean. One can encounter them in a few places in the Eastern Pacific too. Some sea snake species prefer to live in reefs, while other prefer to live close to vegetation near the shore. As they cannot stay submerged for extended periods, they usually forage close to or at the surface.
Hydrophiids (the true sea snakes) give live birth to juvenile snakes while submerged. The gestation period ranges from 4-11 months. Parental care is absent in these species, and juvenile snakes are left to forage individually following birth.
Venom from Sea snake is generally more toxic to humans than venom from terrestrial snakes. However, sea snake fangs are only 1 inch long, and sea snakes are relatively inefficient at penetrating human skin in contrast to their terrestrial relatives. Sea snakes are more inclined to bite humans if threatened than terrestrial snakes, but luckily antivenin against all sea snake bites is available.
1Su Y, Fong SC, Tu MC "Food habits of the sea snake, Laticauda semifasciata" Zoological Studies 44 (3). pp. 403-408 (2005)
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