Rocky Shore Animals

California mussel

Layers of interwoven mussel shells look lifeless when exposed to air, but under water they come alive. The shells open slightly and tiny hairs, or cilia, beat rhythmically to draw in water carrying tiny particles of food. Where waves pound the rocks, mussels out-compete other animals and plants for space. But mussels can't take over completely—other predators, such as lobsters, crabs and sea stars eat them in areas where waves don’t pound as hard. Algae, barnacles and others use the cleared living space.

Bat star

Bat stars come in a wide variety of solid and mottled colors, including red, orange, yellow, brown, green and purple. They have webbing between their short, triangular arms, which gives them a batlike look. Normally, bat stars have five arms, but they occasionally have as many as nine arms.

Monkeyface-eel

Long and eel-like, monkeyface-eels sport a bluntly rounded snout, large fleshy lips and two black lines that radiate from behind their eyes. A dorsal fin runs along the eel’s back. A lumpy ridge appears on adult monkeyface-eels’ heads. Their color ranges from uniform light brown to dark green—some specimens have orange spots on their bodies and orange-colored fin tips.

Acorn barnacle

Acorn barnacles, related to shrimp, hide their identity in snail-like shells. But they begin life as free swimming larvae. When the time comes to settle, the larvae “glue” their heads to hard surfaces, such as pilings, wharfs, ships, rocks or other hard-shelled animals.

Giant green anemone

This green plantlike creature is actually an animal with algae plants living inside it. In this symbiotic relationship, the algae gain protection from snails and other grazers and don't have to compete for living space, while the anemones gain extra nourishment from the algae in their guts. Contrary to popular opinion, this anemone’s green color is produced by the animal itself, not the algae that it eats.