The common starfish is usually orange or brownish in color, and sometimes violet; specimens found in deeper waters are pale.

The common starfish normally has five arms, broad at their base and gradually tapering to a point at their tips, which are often turned up slightly.

There is a line of short white spines running along the centre of the aboral (upper) surface of the arms with low, soft mounds called papulae on either side.

When feeding on a mollusc such as a mussel, it attaches its tube feet to each shell valve and exerts force to separate them slightly.

Even a gap of just 1 mm (0.04 in) is sufficient for the starfish to insert a fold of its stomach, secrete enzymes and start digesting the mollusc body.

It can also detect the odour of the predatory common sunstar (Crossaster papposus), which eats other starfish, and take evasive action.

[11] In January 2013, large numbers of common starfish were washed up near Cleethorpes Pier on the east coast of England along with many razor shells.

The cause of this mass stranding was unknown but bad weather and storms out at sea coupled with higher than usual tides may have been to blame.

This is not a unique phenomenon and other mass strandings have occurred in Britain and elsewhere at such places as near Sandwich in Kent in 2008,[13] and near Brighton ten days later.

[14] A similar occurrence occurred on the shore of the White Sea where vast numbers of starfish came ashore on a nine-mile stretch of beach in 2004.