Diet

• Astropyga pulvinata is a grazing sea urchin that feeds primarily on algae and other organic material growing on the seafloor. Like other diadematid urchins, it uses its Aristotle’s lantern to scrape food from hard surfaces and can also consume detrital material.

Range

• The Cushion Sea Urchin is an eastern Pacific species ranging along the Pacific coast of Mexico from Baja California southward through Central America to Peru. It has been reported from Guerrero, including the Zihuatanejo area.

• It is well documented in Zihuatanejo Bay, where individuals have been photographed underwater at depths typical of the local rocky habitat.

Habitat

• Astropyga pulvinata is a benthic species found on rocky, sandy and fine-sediment bottoms and around rocky or coral reef habitats. It generally occurs in subtidal water, with published depth ranges extending from shallow water to at least several tens of metres.

• Around Zihuatanejo, it is associated particularly with rocky seafloor and reef habitat. It can occur on relatively open substrates where its long spines provide protection from predators.

• Its long, delicate-looking spines are nevertheless an effective defence. The animal can orient the spines towards approaching objects, making contact potentially painful.

Description

• The Cushion Sea Urchin has a somewhat flattened, rounded test that may reach approximately 12–15 cm in diameter, with extremely long, slender spines that can approach the diameter of the test.

• Its colour can vary from dark brown or reddish-brown to violet or nearly black. The most distinctive feature is the pattern of five pale, triangular areas on the upper surface, bordered by rows of brilliant blue to blue-violet iridescent spots.

• The spines may be white, purple or banded with white, turquoise or yellowish colours. Juveniles can have particularly conspicuously banded spines, while adults may have largely white or more uniformly coloured spines.