Sea snakes are not fish, they belong to reptiles and are reptiles. Although sea snakes, like fish, live in water, they are quite different. First of all, the way they breathe is different from the respiratory organs. Fish breathe with gills, and they filter oxygen in water with gills to achieve the purpose of ventilation. Sea snakes breathe through their nose and mouth, so they can't stay in the water for a long time, and need to swim to the water regularly to breathe. Secondly, their activities are different. Fish activities are controlled by fins and tails, while sea snakes move by crawling. They have different activities.

Sea snakes are reptiles, because they live in water, so they are called sea snakes. There are many differences between them and snakes on land. They like to inhabit shallow water. Generally, the depth of water where they live will not exceed 100 meters. Different kinds of sea snakes like to live in different water quality. Some sea snakes like to live in clear water, while others like to live in turbid water.

Most land snakes are non-toxic, but most sea snakes are poisonous because they have anterior groove teeth, which makes them more toxic. Their venom is a great threat to humans and other animals, and if bitten, it may lead to death.