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Clypeaster rosaceusLinnaeus, 1758Clypeaster rosaceus
Common Name: Fat sea biscuit

Turtle grass beds and sand fields bordering turtle grass beds.
Texas, South Carolina to Barbados, Caribbean, Panama.
Natural History Notes
The fat sea biscuit lives on the surface of the sand and frequently covers the upper surface of its test with fragments of turtle grass, shell, and rock. It uses oral surface accessory podia with terminal suckers to ingest dead turtle grass or dead algae. Feeding activity is nocturnal. A single individual is capable of grinding 5.5 kg /year of coarse sand to fine sand, and may play a major role in the production of fine sediment on reefs.
In Panama, C. rosaceus has an annual reproductive cycle; spawning occurs during the rainy season, at random with respect to the lunar cycle. The egg and larva contain a considerable amount of yolk. Metamorphosis occurs after 5-7 days at an average temperature of 27 degrees C.
0-285m, most common at shallow depths
The fat sea biscuit is relatively long (up to 200 mm) and elongate. It is dark brown, and inflated, with a strongly convex upper surface and a concave lower (oral) surface. The test is covered with short spines. It is not uncommon to come upon dead tests, as the naked test is thick and strong.
Other Literature
Lessios, H. A. 1991. Presence and Absense of Monthly Reproductive Rhythms Among Eight Caribbean Echinoids off the Coast of Panama. Journal of Experimental Marine Biology and Ecology. 153(1): 27-48

Levitan, D. R., Young, C. M. 1995. Reproductive success in large populations: Empirical measures and theoretical predictions of fertilization in the sea biscuit Clypeaster rosaceus. Journal of Experimental Marine Biology and Ecology. 190(2): 221-241

Reeves, M. N. and Brooks, W. R. 2001. Host selection, chemical detection, and protection of the symbiotic pinnotherid crabs Dissodactylus crinitichelis and Clypeasterophilus rugatus associated with echinoderms. Symbiosis. 30(4): 239-256.
In Bocas Del Toro
Reported ByHendler, G.; Marine Invertebrate Taxonomy Workshop, Bocas del Toro, August 2003
LocalityEspecially common at Mangrove Inn
ObservationsCommon in Bocas del Toro
Compiled by
Lexi Weintraub
Clypeaster rosaceus
Clypeaster rosaceus
Collin, R., M.C. Diaz, J. Norenburg, R.M. Rocha, J.A. Sanchez, A. Schulz, M.L. Schwartz and A. Valdes. 2005. Photographic identification guide to some common marine invertebrates of Bocas Del Toro, Panama. Caribbean Journal of Science 41: 638-707.

Handler, G., Miller, J. E., Pawson, D. L. and P. M. Kier.1995. Sea Stars, Sea Urchins, and Allies. Smithsonian Institution. Pages:229-230.
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