Lytechinus variegatus (variegated sea urchin) (36011003755)

Description:

Summary[edit] Description: Lytechinus variegatus (Lamarck, 1816) - variegated sea urchin (live captive, Greater Cleveland Aquarium, Cleveland, Ohio, USA). The echinoids are a group of echinoderms - they are starfish relatives. On modern Earth and in the fossil record, echinoids are exclusively marine. Two broad groups exist - the regular echinoids (sea urchins) and the irregular echinoids (heart urchins and sea biscuits and sand dollars). Sea urchins have subglobular to slightly flattened, radially symmetrical skeletons (tests) composed of calcite (CaCO3 - calcium carbonate). The sea urchin test is covered with spines - these readily detach after death. Sea urchins have a mouth with a pentaradial structure called an "Aristotle's lantern" that is used to graze on algae and other biofilms on hard substrates. Irregular echinoids have moderately flattened to significantly flattened, bilaterally symmetrically tests of calcite that are covered with small, short, almost hair-like spines. Most irregular echinoids are infaunal and deposit feeders. The live sea urchin shown above is Lytechinus variegatus, the variegated sea urchin, or short-spined sea urchin. It is in a touch pool tank in a public aquarium. All individuals of this species in the tank had covered themselves with one or more objects - in this case, two bivalve shells, a gastropod shell, and a small rock fragment. Studies suggest that the urchins may be shielding themselves from light (perhaps ultraviolet radiation) and/or the objects may promote orientation stability in shallow, high-energy water. Classification: Animalia, Echinodermata, Echinoidea, Temnopleuroida, Toxopneustidae More info. at: en.wikipedia.org/wiki/Lytechinus_variegatus. Date: 13 July 2017, 13:06. Source: Lytechinus variegatus (variegated sea urchin). Author: James St. John.