Common Starfish

Lore & Background

The common starfish is native to the northeastern Atlantic Ocean and its range extends from Norway and Sweden, through the North Sea, round the coasts of Britain, France, Spain and Portugal and southwards along the coasts of Africa to Senegal. It is largely absent from the Mediterranean Sea. It is also known from the western Atlantic where it occurs between Labrador and Florida and the Gulf of Mexico. It is capable of surviving in brackish water.

In Their Own Story

The Local Coasts exhibit at Living Coasts recreated the underside of a classic English pier, providing a habitat for native marine species including starfish. Visitors could observe these echinoderms alongside other local wildlife such as seahorses, starfish, and edible crabs. The exhibit was part of a larger facility that included a Discovery Zone (opened March 2008) with interactive penguin computer game stations called Penguin Academy, and a Mangroves exhibit (opened July 2009) featuring large aquarium tanks with over 20 species including three types of sting ray. Living Coasts also offered special programs including keeper-for-a-day experiences, penguin feeds, and for certified SCUBA divers, a 45-minute swim with the penguins.

Reader's Guide

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. The oral (lower) surfaces of the arms have rows of small tube feet, used in locomotion and feeding. The starfish is usually orange or brick red on the aboral surface and paler on the oral surface but can also be purple or pale brown. Individuals from deep water are usually paler. It grows to a maximum diameter of about 52 centimetres (20 in) but a more normal size is 10 to 30 cm (4 to 12 in). The common starfish feeds on a variety of benthic organisms including bivalve molluscs, polychaete worms, barnacles, gastropod molluscs, other echinoderms and carrion. 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. The common starfish is dioecious. In the spring, the females release their eggs into the sea. A moderate sized starfish is estimated to be able to produce 2.5 million eggs. The males shed their sperm and fertilisation takes place in the water column. The larvae are planktonic and drift for about 87 days before settling on the seabed and undergoing metamorphosis into juveniles. Common starfish are believed to live for about seven to eight years. When well fed, the juveniles can increase their radius at the rate of slightly more than 10 mm (0.4 in) per month during the summer and autumn and slightly less than 5 millimetres (0.20 in) per month in the winter. An adult common starfish can survive starvation for several months although it loses weight in the process. One specimen shrank from a radius of 6 centimetres (2.4 in) to a radius of 3.8 centimetres (1.5 in) after starvation for five months. The ciliate protozoan Orchitophrya stellarum is sometimes a parasite of the common starfish. It normally lives on the outer surface of the starfish feeding on sloughed-off epidermal tissue. It appears to become parasitic when the host starfish has ripe gonads and is a male. It enters the starfish through the gonopores. The common starf

Did You Know?

• The common starfish can detect the odour of prey species such as the common mussel (Mytilus edulis) and crawl towards it.
• It can also detect the odour of the predatory common sunstar (Crossaster papposus), which eats other starfish, and take evasive action.
• Mass strandings of common starfish have occurred, such as in January 2013 near Cleethorpes Pier on the east coast of England, and during Storm Frank on 31 December 2015 along the coast of Portsmouth, Hampshire.