Here's why:
* Gills: Sharks breathe underwater using gills. Gills extract oxygen from the water and release carbon dioxide. They cannot breathe air.
* Body structure: Their streamlined bodies and fins are designed for swimming, not walking on land.
* Skin: Their skin is covered in scales that are adapted for life in the water.
* Reproduction: Sharks reproduce by laying eggs or giving birth to live young, both of which need water to survive.
There are no known species of sharks that can live permanently on land.