Common Starfish (Asterias rubens)

Common Starfish overview

The common starfish is the most familiar sea star of northwest Europe, found in rock pools, on mussel beds and washed up on beaches. It normally has five tapering arms and is usually orange, though brown, pale and purplish individuals occur, with a line of short white spines down the middle of each arm. Hundreds of tube feet on its underside, worked by water pressure, let it creep along and grip prey. It is an important predator of mussels and can form dense swarms that strip a shellfish bed bare. Like other echinoderms it has no brain and no blood, circulating filtered seawater through its body instead.

How Long Do Common Starfish Live?

Common starfish typically live about 5–10 years in the wild, with 7–8 years often given as usual. Growth depends heavily on food supply: well-fed animals on mussel beds grow large quickly, while starved ones can actually shrink and survive for months. Gulls, crabs, other starfish and winter storms that strand them on beaches are the main causes of death.

How Much Does a Common Starfish Weigh?

An adult common starfish weighs roughly 50–400 g (2–14 oz), depending on its size and how recently it has fed. This is an approximate range, because weight varies enormously between a 10 cm animal and a 30 cm one and with the amount of seawater held in the body.

How Long Is a Common Starfish?

Common starfish usually measure 10–30 cm (4–12 in) from arm tip to arm tip. The largest recorded reached about 52 cm (20 in) across, but animals that big are rare and are found in deeper water. Those in rock pools and on the shore tend to be small.

What Do Common Starfish Eat?

Common starfish are carnivores that feed mostly on mussels and other bivalves. A starfish wraps its arms around the shell, pulls steadily with its tube feet until the valves part by a millimeter or so, then pushes its own stomach out through its mouth and into the gap to digest the animal inside its shell.

Diet type: carnivore. Mainly mussels, clams, oysters and other bivalves, which it pulls open with its tube feet, plus barnacles, sea snails, worms, small crustaceans and carrion.

Where Do Common Starfish Live?

Common starfish live on rocky shores, mussel and oyster beds, and sand or gravel bottoms in the northeast Atlantic, from low-tide rock pools down to about 200 m (650 ft) and occasionally deeper. They tolerate reduced salinity and extend into estuaries and the western Baltic Sea.

Are Common Starfish Endangered?

The common starfish has not been evaluated for the IUCN Red List and is abundant throughout its range. It is regarded as a pest by mussel and oyster farmers, who sometimes remove starfish from shellfish beds with special mops or dredges. Mass strandings of thousands after storms are natural events and do not indicate decline.

Not Evaluated

Common Starfish fun facts

• A common starfish can regrow a lost arm, and it will deliberately shed an arm that is seized by a predator.
• Each arm ends in a tiny red eyespot that senses light and dark, so a five-armed starfish has five simple eyes.
• A large female common starfish can release around 2.5 million eggs in a single spawning season.
• Starfish have no blood; a water vascular system pumps filtered seawater through the body and powers the tube feet hydraulically.
• Its larva looks nothing like a star: it is a transparent, bilaterally symmetrical swimmer that drifts in the plankton for about three months before settling.

Common Starfish FAQ

Related animals

All invertebrates