Creature Feature Encyclopedia: Cephaloda

Chambered Nautilus Nautilus pompilius Size: to 8" diameter (20 cm)

The Chambered Nautilus has existed for 450 million years. It got its name from the numerous compartments in its shell, which enable it to move vertically through 1,000 feet of ocean. To rise, the nautilus fills the chambers with gas; to sink, it absorbs the gas back into its body, filling the shell with water. To move horizontally, the nautilus contracts its body, allowing water to enter its shell. Then by expanding its body, it pushes the water out through a tube called a siphon. This jet-like movement thrusts the nautilus through the water. Like a "living submarine," the nautilus spends its days deep in the ocean, and feeds near the surface at night.

~A Swim through the Sea © 1994