The larva are blind and toothless, and feed by filtering. The larva remain in the hole for about four years. They develop into adults after this. The lampreys often feed on the blood of other fish. Since lampreys are cold blooded, they have low metabolic needs.
Lampreys live in salt and fresh water, and reproduce in fresh water.
The lamprey is like a long slimy tube, with a notochord made of cartilage, and a jawless mouth with a large amount of teeth. Lampreys live in most of the world's seas and fresh water streams. A lamprey living in a certain climate has adapted to the climate it lives in. The ecological niche of the sea lamprey is salt water for living, and fresh water for breeding. Most breed in October.