FAMILY HYDROPHIIDAE (SEA SNAKES)
The Sea Snakes are specifically adapted to a marine existence. They have vertically flattened tails, valvular nostrils, and other distinctive characteristics. These snakes are believed to have originated from the same stock as modern Elapids as they are also front fanged and in general highly venomous. Little research has been done to date on the toxicity of sea snake venoms, although most species are believed to be potentially
dangerous. No Sea Snakes are aggressive, and considering that large numbers of fishermen come into contact with sea snakes on a daily basis, bites are rare.
Sea Snakes are able to rapidly dive deeply and surface again without getting that human affliction called 'bends' caused by air bubbles forming in the bloodstream. With the exception of one species which is found throughout the Indian and Pacific oceans, Sea Snakes are restricted to South East Asia and Australia. About fifty species have currently been described, of which over 30 are recognised as coming from Australian waters. Most Australian varieties are only found in northern waters.
All except two species are live bearers, and those two species have been placed by some researchers in a separate family, (Laticaudidae), (As done earlier in this book).

The above was from the book Australian Reptiles and Frogs by Raymond Hoser and now available on a fantastic CD-Rom along with a vast amount of other information, papers and the like on reptiles, frogs and other wildlife.