Spiny Sea Star

Spiny Sea Star, Amphiaster insignis

Spiny Sea Star, Amphiaster insignis. Pictured star’s wingspan: 12.5 cm (4.9 inches). Exceedingly rare. Identification courtesy of Dr. Chris Mah, Smithsonian Institute, Washington, D.C.

The Spiny Sea Star, Amphiaster insignis (Verrill, 1868) is a member of the Asterodiscididae Family of Asterodiscid Sea Stars, that is also known as the Red Spiny Sea Star and in Mexico as estrella espinosa. There is just one global member of the Amphiaster Genus, this species, which is found in Mexican waters of the Pacific Ocean.

Spiny Sea Stars have a wide central disc and 5 triangular arms. The dorsal or aboral surface and the marginal surfaces of the disc and arms are covered with numerous, sharp, conical spines. They range in color from reddish brown to reddish-orange or black. Spiny Sea Stars reach a maximum of 17.4 cm (6.9 inches) in diameter.

The Spiny Sea Star is found over mud and sand substrate from the intertidal zone to depths up to 128 m (420 feet). They feed on algae, echinoderms, and other small invertebrates. The Spiny Sea Star is rare, seldom seen by humans, and very little is known about their behavioral patterns.

The Spiny Sea Star is a resident of Mexican waters of the Pacific Ocean but they have a limited distribution being found from Magdalena Bay, Baja California Sur, southward along the coast of the mainland to Guatemala including throughout the Sea of Cortez.