Cushion Star

Overview

The Cushion Star (Asterina gibbosa) is a small, distinctive starfish often found in shallow coastal waters and rock pools. It is well-adapted to life in the intertidal zone, where it frequently hides under rocks or within crevices to avoid light and desiccation.

Appearance

This species has a characteristic pentagonal, cushion-like shape with five very short, blunt arms. Its upper surface is rough, covered in groups of short, stiff spines. The coloration is highly variable, ranging from shades of green, gray, and brown to orange or yellow, often appearing mottled to help it blend into its surroundings. Adults typically reach a diameter of 5 to 7 cm.

Distribution & Habitat

Asterina gibbosa is native to the northeastern Atlantic Ocean, including the English Channel and the British Isles, as well as the Mediterranean Sea. It thrives in various environments, including rocky shores, seagrass meadows, and sheltered coastal lagoons. While it can be found at greater depths, it is most commonly encountered in shallow, damp habitats like rock pools.

Biology & Behavior

This starfish is primarily nocturnal, spending daylight hours sheltered under boulders or in dark crevices. It is a slow-moving creature, often remaining stationary for long periods. It is notably hardy, capable of tolerating variations in both salinity and temperature.

Feeding

As an opportunistic feeder, the Cushion Star consumes a variety of organic matter, including diatoms, algae, sponges, and small animals like barnacles or bivalves. It feeds by extending its stomach over its food source to secrete digestive enzymes.

Reproduction

Reproduction is sexual, involving external fertilization. The species can be gonochoric (separate sexes) or hermaphroditic, with some individuals exhibiting protandry, where male gonads develop first. Eggs are typically attached to hard substrates or algae, where they develop directly into juvenile starfish.