Amphiuridae

Amphiuridae, also known as long-armed burrowing brittle stars, form a large family within the suborder Gnathophiurina. This group is the most diverse in the order Ophiurida, containing over 200 species. Some members, such as Amphipholis kochii and Amphioplus abditus, are used to study how echinoderms develop, while the dwarf brittle star Amphipholis squamata is a model for research on bioluminescence.

These brittle stars are generally small. Their jaws always have two apical papillae at the tip, with one or more additional papillae on each side.

Amphiurids live in oceans worldwide, from the tropics to the Arctic and Antarctic, and a few species tolerate brackish water. They mostly burrow into the seafloor or hide beneath rocks. Most feed on algae or detritus, using their long arms to move organic matter toward their mouths.

While many amphiurids release eggs and sperm into the water, numerous species in this family brood their young inside bursae. For instance, one adult of Amphiodia akosmos from California’s Monterey Peninsula was found carrying up to 11 embryos (Hendler and Bundrick, 2001). Two extinct genera are also known: †Deckersamphiura (Jagt, 2000) and †Xanthamphiura (Hess, 1970).