Hagfishes: Myxini

Hagfishes live in large groups on the ocean floor. They defend themselves by producing slime. Their reproductive patterns are unknown. Fertilization (FUR-teh-lih-zay-shun), or the joining of sperm and eggs to begin development, is probably external, or outside the body. Male reproductive cells are called sperm and female's are called eggs. The fishes release eggs and sperm into the water, and eggs that come into contact with sperm are fertilized. Each clutch, or group of eggs, contains twenty to thirty yolky eggs that are 0.8–1 inch (2–2.5 centimeters) long. The eggs are enclosed in a tough shell with threads at each end, which anchor the eggs in the mud.