Sea Biscuit, Clypeaster Sp.

Sea Biscuit, Clypeaster Sp. Size: 6.0 cm (2.4 inches) x 4.5 cm (1.8 inches) x 4.2 cm (1.7 inches). Collection courtesy of Bob Hillis, Ivins, UT, made in coastal waters of the greater Los Cabos area of Baja California Sur.

Sea Biscuit, Clypeaster Sp. Collected from within Zihuantanejo Bay, Guerrero, March 2020. Photographs courtesy of Ron Woheau, Zihuantanejo. Size: 4.8 cm (1.9 inches) x 4.2 cm (1.6 inches) x 3.4 cm (1.3 inches).

Sea Biscuit, Clypeaster Sp. Collected from within Zihuantanejo Bay, Guerrero, March 2022. Photographs courtesy of Ron Woheau, Zihuantanejo. Size: 4.8 cm (1.9 inches) x 4.2 cm (1.6 inches) x 3.4 cm (1.3 inches).

Sea Biscuits are very similar to Sand Dollars with inflated shells, and both are related to Sea Urchins. The exterior of living animals are covered with small, bristle-like spines. The name Clypeaster means Flowered Round Shield. This refers to the shape of the animal and to the 5 “petaled” flower shape on top of the animal. At the center of this flower is the madreporite. The madreporite is part of the animal’s water vascular system and supports respiration, feeding, and locomotion. Sea Biscuits live in soft sediments and feed by filtering plankton and detritus from the surface of the sediment. There are reports that there are four Sea Biscuits in residence in Mexican waters of the Pacific – Clypeaster europacificus, Clypeaster ochrus, Clypeaster rotundus and Clypeaster speciosus. Of these only Clypeaster europacificus has photographs available on the internet and it can be eliminated as an option as its test is significantly different.

There are reports that there are four Sea Biscuits in residence in Mexican waters of the Pacific – Clypeaster europacificus, Clypeaster ochrus, Clypeaster rotundus and Clypeaster speciosus. Of these only Clypeaster europacificus has photographs available on the internet and it can be eliminated as an option as its test is significantly different.