Identification Photos: Keeled Starfish, Asteropsis carinifera: The Keeled Starfish is characterized by a ridge of spines in the center of each arm, a flattened wide body and triangularly shaped arms. It also has fairly long spines along the edge of each arm (as pictured below).

The Keeled Starfish reaches a maximum of about 10 inches wide and is found around intertidal reefs to depths of 120 feet. It feeds on microfauna, bethic algae, seagrass, and other echinoderms. In Mexican waters, the Keeled Starfish is present throughout the Sea of Cortez but most abundant in the central gulf. It appears to be absent from along the Pacific side of Baja California and from along the coast of the Mexican mainland.

The Keeled Starfish is a common member of the Echinoderm phylum of marine animals and is a member of the Asteroidea Class and the Oreasteridae Family. The Echinoderms include brittle stars, sea cucumbers, sea lilies, starfish and urchins and are of great scientific interest because, via fossil records, they date to the Cambrian Age (over 500 million years ago) with species numbering 7,000 living and 13,000 extinct. The starfish or sea stars have a unique water-vascular system that uses hydraulic power to operate a multitude of tiny tube feet that are used in locomotion and food capture. Some feed via extending the stomach out through the mouth, surrounding the prey, secreting enzymes to digest the food, and then retracting the stomach when finished eating. They exist from intertidal zones to depths of 30,000 feet with 1,500 species known globally. The bodies are flattened, flexible and covered with colored skin.

Keeled Starfish, Asteropsis carinifera: “Caught” from shore midmorning in 74-degree water, in April 2002, in sand bottom adjacent to rocky structure, 10 yards from shore, utilizing a paw, 25 kilometers north of La Playita, San Jose del Cabo, Baja California Sur, Mexico, on the East Cape road. Size approximately 6 inches. Super model Lori Cisterna hired to illustrate size of species. Description and photo courtesy of John Snow.