Up to 2m
With streamlined, boat-shaped bodies and flattened, paddle-like tails, sea snakes are well adapted to marine life and helpless on land. To prevent water entering lungs, valves close the nostrils while submerged. This is typically for about 30 minutes, although some can remain underwater for up to 2 hours. A special gland under the tongue concentrates and excretes excess salt.
Diet and habitat
Sea snakes prefer the warmer, shallower parts of the Indian and west Pacific Oceans and are found in a variety of habitats from mangroves, estuaries and reefs to the open ocean. They eat fish and some will also feed on fish eggs, molluscs and crustaceans. Sea snakes are often seen from the Denham jetty in Shark Bay.
Female sea snakes give birth to live young at sea. Sea kraits are another group of snakes that live in the sea but lay eggs on land.
At least 22 species of sea snake have been recorded in Western Australia. The three most common in Shark Bay are the olive-headed sea snake (Hydrophis major), elegant sea snake (H. elegans); and Shark Bay sea snake (Aipysurus pooleorum), which is unique to the region. Less common is the turtle-headed sea snake (Emydocephalus annulatus).
While many WA sea snakes are common, Shark Bay also hosts the critically endangered leaf-scaled sea snake (Aipysurus foliosquama) and short-nosed sea snake (A. apraefrontalis).