About Ophiocomella alexandri (Lyman, 1860)
This species of brittle star, Ophiocomella alexandri, is pentaradially symmetric, with five arms attached to a central rounded disk. The upper surface of the central disk is covered in small bumps, and the disk can reach up to 25.2 millimetres (0.99 in) across; it holds the animal's mouth, digestive system, and gonads. When fully extended, the arms bring the total diameter of the brittle star to up to 450 millimetres (18 in). The arms are very flexible, and as the common name implies, they are quite spiny, with five to seven long spines on each lateral plate. The animal is dark brown overall, with lighter bands on the upper sides of its arms. These lighter areas are gray with subtle yellow tones. The species' coloration changes on a daily cycle; both this daily change and the banded pattern may act as camouflage to hide the brittle star from predatory fish. Males and females of this species look identical to one another. Ophiocomella alexandri is a benthic brittle star that lives on the seabed, ranging from the intertidal zone down to a depth of 70 meters (230 feet). It favors rocky seabeds and coral reef habitats. This species is found in the eastern Pacific Ocean, ranging from southern California to Colombia, including the Gulf of California and the Galapagos Islands.
