Although the name sea serpent
has come to mean almost invariably a mythical sea monster
, there are true sea snakes
of several different species belonging to a group related to cobrass
. They are only moderately large. 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.
Sea snakes are poisonous. They have short grooved fangs near the front of the upper jaw, and the poison acts on the nervous system like that of the related cobras.
Sea snakes are confined to the tropical oceans, chiefly the Indian ocean and the western Pacific ocean. A single species, Pelamydrus platurus, extends to the eastern Pacific.