Stylasterias

Lore & Background

The velcro star is a large starfish, growing to a maximum diameter of 100 cm, though usually smaller. Its central disc is small, and its five (occasionally six) arms are long and tapering. Rows of large spines run down the arms, each surrounded by a ring of 30-40 pedicellariae—tiny pincer-like structures. Between the spines are tufts of pale gills. The common name comes from the surface feeling sticky to the touch, caused by the pedicellariae gripping the skin; any attempt to push it off results in further pedicellariae becoming aroused. The colour is some shade of grey or black, or occasionally beige.

The velcro star occurs on the Pacific coast of North America, from Kodiak Island, Alaska, to Southern California, at depths to about 530 m. It is generally uncommon and mostly occurs in deep water at the head of fiords.

It feeds on invertebrates such as gastropod molluscs and chitons. When alert to movement in the water, the rings of pedicellariae are extended. If anything touches its aboral (upper) surface, the starfish snaps shut the pedicellariae in the vicinity, catching prey such as small fish. The victim is passed to the mouth by arm movements and tube feet. It can also defend itself against predators like the morning sun star (Solaster dawsoni) by coiling its arms around the attacker and inflicting thousands of nips with its pedicellariae, often causing the attacker to retreat.

Reader's Guide

Stylasterias is significant as a monotypic genus within the family Asteriidae, represented solely by Stylasterias forreri, the velcro star. Its most distinctive feature is the adhesive surface created by its pedicellariae, which gives it a unique defensive and predatory mechanism. The species is notable for its ability to catch small fish by snapping shut its pedicellariae upon contact, and for its defensive behavior against predators such as the morning sun star, where it coils its arms and delivers thousands of nips. The velcro star is generally uncommon and inhabits deep waters along the Pacific coast of North America, from Alaska to Southern California, often at the heads of fiords. Its large size—up to 100 cm in diameter—and its unusual stickiness make it a remarkable example of adaptation in starfish. The species' reliance on pedicellariae for both feeding and defense highlights the evolutionary specialization within the genus. Its occurrence in deep, fiord habitats contributes to its rarity and ecological niche.

Did You Know?

• The velcro star gets its name because its surface seems sticky to the touch, caused by pedicellariae gripping the skin.
• It can grow to a maximum diameter of 100 cm (39 in).
• It defends itself against the morning sun star by coiling its arms and inflicting thousands of nips with its pedicellariae.
• It is found at depths to about 530 m (1,740 ft) on the Pacific coast of North America.