Amphiuridae


Amphiuridae are a large family of brittle stars of the suborder Gnathophiurina. Some species are used to study echinoderm development and bioluminescence.

Characteristics

Amphiuridae are generally small brittlestars. Their jaws are always with two apical papillae at the tip, and one or more papillae on each side.

Systematics and phylogeny

Amphiuridae are the most diverse family of Ophiurida with over 200 species. The family contains the following genera:Acrocnida Gislén, 1926Ailsaria Fell, 1962Amphiacantha Matsumoto, 1917Amphichilus Matsumoto, 1917Amphichondrius Nielsen, 1932Amphicontus Hill, 1940Amphigyptis Nielsen, 1932Amphilimna Verrill, 1899Amphilycus Mortensen, 1933Amphinephthys Fell,1962AmphiocnidaAmphiodia Verrill, 1899Amphiomya H.L. Clark, 1939Amphioncus Clark, 1939Amphioplus Verrill, 1899Amphipholis Ljungman, 1966Amphistigma H.L. Clark, 1938Amphiura Forbes, 1842Ctenamphiura Verrill, 1899Diamphiodia Fell, 1962Dougalopus A. M. Clark, 1970Gymnodia Fell, 1962Icalia Fell, 1962Microphiopholis Turner, 1985Monamphiura Fell 1962Monopholis Fell, 1962Nannophiura Mortensen, 1933Nudamphiura Tommasi, 1965Nullamphiura Fell, 1962Nullopholis Fell, 1962Ophiocnida Lyman, 1865Ophiomonas Djakonov, 1952Ophionema Lütken, 1869Ophionephthys Lütken, 1869Ophiophragmus Lyman, 1865Ophiostigma Lütken, 1856Pandellia Fell, 1962Paracrocnida Mortensen, 1940Paramphichondrius Guille & Wolff, 1984Paramphiura Koehler, 1895Silax Fell, 1962Triodia A.M. Clark, 1970Unioplus Fell, 1962
In addition, two extinct genera are known:

Ecology

Amphiuridae are found in oceans worldwide from tropics to Arctic and Antarctic regions, with some species living in brackish water. They live mostly by burrowing in the seafloor or hiding under rocks. Most of them are herbivores feeding directly on algae, or detritus feeders, using their long arms to direct organic materials towards their mouths.
Though most amphiurid brittlestars broadcast their eggs and sperm into the sea, many species in this family are "brooders" and carry their young in bursae. One species, Amphiodia akosmos from the Monterey Peninsula of California, was found with up to 11 brooding embryos in one adult.