The nostrils of sea snakes face upwards and have valves to open and close. After inhaling air, they can close their nostrils and dive underwater for up to 10 minutes. The surface of the body is covered with scales, and beneath the scales is a thick skin that prevents the infiltration of seawater and the loss of body fluids. The salt glands under the tongue have the function of expelling excess salt that enters the body with food.

The small sea snake is half a meter long, and the large sea snake can reach 3 meters or so. Sea snakes live along the coast, especially in brackish estuaries, where they feed on fish. There is no pain when biting by a sea snake, and there is an incubation period for the onset of its toxicity. There are no obvious symptoms of poisoning within 30 minutes or even 3 hours after being bitten by a sea snake. However, this is very dangerous and can easily make people paralyzed. People who are bitten can die within hours to days.