There are probably more sea snakes in the world than any other kind of snake. Sea snake is the common name for certain marine members of a family of snakes that inhabit the waters from the Indian to the Pacific oceans. They are highly venomous; in fact, some are many times more toxic than any known land snake, with venom from 10 to 40 times more potent than that of the cobra.
Most sea snakes are not large, ranging from about 1 ½ - 3 feet (0.5 to 1 meter) in length. They are air breathers but they have valves over their nostrils that close underwater. They can hold their breath for long periods while hunting and even sleeping, as long as 8 hours, but must eventually come to the surface for a quick breath of air. The paddle-like tail of sea snakes is wide and compressed and makes an effective swimming tool. They have modified lungs to help them maintain buoyancy and to remain underwater.
Eels are often mistaken for sea snakes; in fact, some eels resemble sea snakes so much they are called "snake eels." But eels are not venomous and have no fangs. And sea snakes differ from eels in that they have scales and no gill slits.
Persistent myths about sea snakes include the mistaken idea that they can't bite very effectively. The truth is that their short fangs are adequate to penetrate the skin, and they can open their small mouths wide enough to bite a table top. Even a small snake can bite a man's thigh.
The bite of the sea snake is painless. However, within a half hour the victim will experience stiffness, muscle aches, spasm of the jaw and pain in the affected limb. The powerful neurotoxins can also cause blurred vision, drowsiness and respiratory paralysis. Treatment is possible with sea snake antivenin or tiger snake antivenin.
Luckily, sea snakes are shy and avoid contact with people. Even if they inflict a bite, they will usually use a small amount of venom, which they normally use for immobilizing prey rather than killing it. As with other snakes, you should exercise caution when sea snakes are around. In most instances, if you leave them alone, they'll leave you alone.