What are brittle stars?
Brittle stars belong to Phylum Echinodermata and Subclass Ophiuroidea which has about 2,100 known species. This makes Ophiuroidea the largest group of echinoderms. About 300 brittle star species are found in shallow tropical waters. Features: Brittle stars are related to sea stars but belong to a different class and have somewhat different features and habits. Like other echinoderms, brittle stars are symmetrical along five axes, have spiny skin and tube feet. An armful: A brittle star is almost all arms. Its central disk is usually only a few centimeters wide while its thin, flexible arms can be very long. The arms are made up of large, well developed ossicles (plates made mostly of calcium carbonate). The ossicles are connected together like a vertebrate with ball-and-socket joints. A brittle star lengthens its arms by adding ossicles where the arm joins the central disk. Sometimes confused with bristleworms. Here’s more on how to tell them apart. Feather stars may also appear simila
