Fish Notes Class Agnatha Jawless Fish General Fish

Fish Notes Class: Agnatha Jawless Fish

General Fish Information • Fish make up half of all vertebrates on Earth. • 15, 300 marine species • 9, 000 freshwater species • They first appeared more than 500 million years • ago. 3 groups of fish 1. Jawless – Class Agnatha 2. Cartilaginous – Class Chondrichthyes 3. Bony – Class Osteichthyes • Fish – The term “fish” refers to a single individual or more than one of the same species. • Fishes – the term “fishes” refers to more than one species of fish.

3 Main Body Parts • 1. Fins – movement

3 Main Body Parts 2. Scales • protection. • Many species secrete a protein-like “slime” that contains natural antibiotics to protect them from disease. • On many bony fish species you can count the rings on the scales to determine age.

3 Main Body Parts 3. Gills • Oxygen exchange. • in through the mouth • out through the gills • Oxygen passes out of water into bloodstream by diffusion.

Jawless Fish – Class Agnatha 1. Lamprey: • Parasites • Primarily freshwater fish – • • • breed in rivers and lakes and some move to saltwater as adults. Sucker-like mouth with hornlike teeth Attach to fish and suck up tissues and body fluids of host. Lampreys have an anticoagulant in the saliva that keeps the blood of the victim fluid. Lamprey Mouth

Jawless Fish – Class Agnatha • Hagfish • * no eyes, jaws, scales or paired fins • * worm-like body • * 4 -6 short tentacles around the mouth • * toothed tongue • * scavengers or parasites of slow moving fish • * produce enormous amounts of slime – 5 gal/min • * The slime is a defense mechanism. – slime cocoon • * Uses a knot to get rid of slime - also sneezes Hagfish slime