Sea
snakes are extremely well adapted for life in the ocean. In fact, most
species of sea snake are so well adapted that they never come back onto
land. Their bodies have evolved to become laterally compressed, and
their paddle-like tail helps with movement through the water. They must
surface for air, but their lung is huge and extends almost the entire
length of the body, and is used for both re
spiration
and buoyancy. Most species also have the ability to respire through the
top of their skin, allowing for better oxygen exchange and longer
dives. Special glands allow the snake to expel excess salt through
tongue movement. Sea snakes are also ovoviviparous, meaning they give
birth to live young in the water, with the exception of one genus
(Laticauda) which is oviparous and lays its eggs on land. Sea snakes are
also one of the most venomous animals on the planet, but there is
little to fear from them. They are normally docile animals and shy away
from beaches and divers, although they may bite when provoked,
especially during breeding season.
But not all sea snakes are docile. Enhydrina schistosa, the beaked sea snake, is much more aggressive than its cousins and also happens to be one of the most venomous sea snakes. It lives in Australia and the Indo-Pacific region, and occurs in estuaries and shallow reefs, where they commonly encounter fishing nets and swimmers. Their habitat and aggressive nature makes them deadly, with more recorded attacks than any other sea snake. However, they normally mind their own business and hunt their favorite food, the spiny catfish and blowfish, which they catch using their wide mouth, beaked snout, and venom.
The beaked snout has been an easy way to recognize and catalog E. schistosa, and has been used for many years, but genetic testing has completely changed the way we think of these animals. Turns out, the beaked sea snake is actually two species... one that lives along the coast of Australia, and one that occurs around Indonesia. It's easy to assume that two sea snakes that look identical and behave the same way would be related, or at least sub-species, but genetic testing has shown that these two species are not even remotely related! The Asian beaked sea snake is more closely related with other Asian sea snakes, while the Australia beaked sea snake, now known as Enhydrina zweifeli, occurs on a completely different branch of the tree. Genetic testing also suggests that the two species of sea snake are reclassified under the genus Hydrophis, as they are both deeply embedded in this group. Hydrophis makes up the majority of sea snakes in the Australian and Indo-Pacific area.
This is a perfect example of convergent evolution, where two unrelated species evolve to suit a similar niche. Both species prefer to eat the same prey (blowfish and other spiny fish), where the beaked nose would have been preferred. There are slight differences between the two, such as the number of stripes, that have become more apparent since the discovery. This goes to show that the tree of life is always changing according to new discoveries, and biology is never set in stone.
http://
http://scienceblogs.com/
Image credit: dna-barcoding.blogspot.com
But not all sea snakes are docile. Enhydrina schistosa, the beaked sea snake, is much more aggressive than its cousins and also happens to be one of the most venomous sea snakes. It lives in Australia and the Indo-Pacific region, and occurs in estuaries and shallow reefs, where they commonly encounter fishing nets and swimmers. Their habitat and aggressive nature makes them deadly, with more recorded attacks than any other sea snake. However, they normally mind their own business and hunt their favorite food, the spiny catfish and blowfish, which they catch using their wide mouth, beaked snout, and venom.
The beaked snout has been an easy way to recognize and catalog E. schistosa, and has been used for many years, but genetic testing has completely changed the way we think of these animals. Turns out, the beaked sea snake is actually two species... one that lives along the coast of Australia, and one that occurs around Indonesia. It's easy to assume that two sea snakes that look identical and behave the same way would be related, or at least sub-species, but genetic testing has shown that these two species are not even remotely related! The Asian beaked sea snake is more closely related with other Asian sea snakes, while the Australia beaked sea snake, now known as Enhydrina zweifeli, occurs on a completely different branch of the tree. Genetic testing also suggests that the two species of sea snake are reclassified under the genus Hydrophis, as they are both deeply embedded in this group. Hydrophis makes up the majority of sea snakes in the Australian and Indo-Pacific area.
This is a perfect example of convergent evolution, where two unrelated species evolve to suit a similar niche. Both species prefer to eat the same prey (blowfish and other spiny fish), where the beaked nose would have been preferred. There are slight differences between the two, such as the number of stripes, that have become more apparent since the discovery. This goes to show that the tree of life is always changing according to new discoveries, and biology is never set in stone.
http://
http://scienceblogs.com/
Image credit: dna-barcoding.blogspot.com
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