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What are they?
Lampreys and hagfish can be termed as the living fossils, not because they
might not have changed, but because they are the most ancient of all fish. They
come under the least fond class of fish - the jawless ones. They together (
30 species of lampreys and 15 of hagfish ) form less than 1 per cent of all
known fish species of today. Lampreys are adaptable and live in both fresh and
salt water. Hagfish live only in the salt water, and is found in the seas.
How do they live?
Lampreys and hagfish have one feature in common - slimy slippery bodies that are scale less and in the shape of an eel - a slithering thin body, somewhat like a snake. But these fish are not in the eel family. Eel's are teleosts.
Lampreys and hagfish are like cartilaginous fish - they have a skeleton of cartilage. But they do not come under cartilaginous fish as they are jawless. To make up for this deficiency a lamprey's mouth has a round sucker ( or a sucking organ ) and a toothed tongue. They use their tongue to cut into the flesh of a victim and using the mouth, the blood. Hagfish, on the other hand, possess a slit-like mouth with teeth.They are scavengers and feed on dead fish.
From where did they evolve and when?
From where is not accurately known, but they evolved in early times ( when fish originally evolved ).
