Characteristics: The bodies of starfish are very different from those of most other animals. The European starfish has five identical arms radiating from a flat central area, and other starfish have as many as 50 arms. The central area contains the mouth (on the bottom), the anus (on top), and the main stomach organs in between. 

Bony plates in the starfish’s body give it support. All over the surface there are tiny pincers that snap shut to defend against creatures that try to settle on the starfish. Sensitive tube feet with suction pads line the bottom of each arm. These podia detect and trap prey. To move forward, the starfish repeatedly extends its tube feet and fixes each to a new spot.

Food and Feeding: Some starfish filter nutritious particles from the water, but most, including the European starfish, are predators. They eat sponges, corals, worms, mollusks, crustaceans, other starfish, and small fish. They use their tube feet to detect prey from chemical signals in the water and to ensnare their victims.

The European starfish is especially fond of bivalve mollusks such as mussels, oysters, and clams. These creatures seal their shells tight when attacked, but the starfish wraps its body around the prey and uses its tube feet to pull the two halves of the shell slightly open. It extends its stomach outward through its mouth and into the shell itself. The starfish releases digestive juices that break down the victim’s tissue. The resulting soupy mixture is absorbed into the extended stomach. A starfish usually moves only when feeding or if the seabed temperature changes.

Breeding: The male and female European starfish look similar. During the spring spawning season, they produce millions of sex cells and release them into the water through special pores. When a female releases sex cells, she triggers neighboring males and females to release theirs, and many of the cells intermingle. A fertilized egg hatches into a floating, bean shaped, symmetrical larva. It grows twelve arms and floats near the surface for several more weeks. Eventually its arms are replaced by three new arms. The larva inverts itself and, using its three arms and a suction foot, anchors itself to the seabed. A star shaped bud grows on the rear of the larva and eventually takes over. After a year it is a mature, but small, adult, measuring four inches across.

Naturewatch: European starfish are often found on mussel beds. Other European species include the cushion star, with stubby arms, and the sunstar, with 10 or more arms. The dry remains on beaches are the animal’s bony plates. The softer parts have usually decomposed or been eaten.

Key Facts:
Sizes:
Length: Up to 18 in. across
Arm length: Up to 10 in.

Breeding:
Sexual maturity: 1 year
Spawning season: Spring
No. of eggs: About 2.5 million eggs in each spawning
Larval stage: About 2 months

Lifestyle:
Habit: Occurs where prey is abundant. Creeps across seabed using tube feet
Diet: Mainly bivalve mollusks, especially oysters, mussels, and scallops

Related Species: There are about 1,600 species of starfish in 31 families, distributed throughout the oceans of the world. The family Asteriidae includes numerous species in North America.

Distribution: Found on the coasts of northern and western Europe and northwest Africa, from the lower shore to 650 feet below sea level.

Conservation: The European starfish is still common and widespread throughout its range, but some are collected, dried, and sold as decorative trinkets.

Features of the European Starfish:
Outer surface: Supports many tiny pincers that snap shut on intruding creatures to deter or even kill them.
Outer wall: Very flexible. Made mostly from muscle fiber and bony supports.
Sex cell organs: Occur in each arm and release sperm or eggs.
Fluid system: Muscular podia are filled with fluid and operate much like water pumps. As they become longer or shorter, the pressurized fluid inside moves accordingly.
Digestion: From the mouth (underneath) food enters the stomach. Organs in each arm make digestive juices and store food. Waste is expelled from the anus.
Spines: Cover the starfish’s upper surface.
Podia: Tube feet under each arm, tipped with suction pads. They enable the starfish to walk and to open its prey. They also absorb oxygen.

Did You Know: 
Adult starfish consume three times their weight in food every day. Young starfish may eat 10 times their body weight.
Crown of thorns starfish graze on living coral. They recently destroyed large sections of Australia’s Great Barrier Reef.
 

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