California mussel
Mytilus californianus
- On view
- Rocky Shore
- Animal type
- Invertebrates
- Ecosystem
- Rocky shore
- Relatives
- Clams and other bivalves; Phylum: Mollusca
- Diet
- Fine organic detritus and living plankton filtered from sea water
- Range
- Alaska to Baja California
- Size
- Up to 5 inches (12.7 cm)
Meet the California mussel
When exposed to air, mussels become fortresses, protecting themselves against the elements. Under water, they become active. Their shells open slightly and tiny hairs, or cilia, beat rhythmically to draw in water that carries tiny particles of food. Where waves pound the rocks, mussels compete against barnacles and other animals and plants for space.
Natural history
The California mussel attaches to rocks (and other mussels) by fibers called byssal threads. These threads are produced in liquid form by the byssal gland. The liquid runs down a groove formed by the foot. When the foot pulls back, exposing the liquid to seawater, the liquid solidifies into a thread.
Conservation
Though it may look rugged, the rocky shore habitat is fragile. Rocky shore creatures are at risk from coastal development and pollution (including waste oil and agricultural runoff). And some tide pools are in danger of being “loved to death” by visitors. Tread lightly as you explore tide pools to avoid crushing plants and animals, and never take creatures from their habitat.
Cool facts
- To collect enough food to survive, a mussel filters two to three quarts (about two to three liters) of water an hour!
- A California mussel grows to full size in about three years.
- Mussels can grow in very large groups, sometimes numbering a million or more.
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