Amphiuridae (commonly called long-armed burrowing brittle stars or burrowing brittle stars) are a large family of brittle stars of the suborder Gnathophiurina. Some species are used to study echinoderm development (e.g. Amphipholis kochii and Amphioplus abditus) and bioluminescence (the dwarf brittle star, Amphipholis squamata).

Characteristics

Amphiuridae are generally small brittlestars. Their jaws are always with two apical papillaee 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, 1926

• Ailsaria Fell, 1962

• Amphiacantha Matsumoto, 1917

• Amphichilus Matsumoto, 1917

• Amphichondrius Nielsen, 1932

• Amphicontus Hill, 1940

• Amphigyptis Nielsen, 1932

• Amphilimna Verrill, 1899

• Amphilycus Mortensen, 1933

• Amphinephthys Fell,1962

• Amphiocnida

• Amphiodia Verrill, 1899

• Amphiomya H.L. Clark, 1939

• Amphioncus Clark, 1939

• Amphioplus Verrill, 1899

• Amphipholis Ljungman, 1966

• Amphistigma H.L. Clark, 1938

• Amphiura Forbes, 1842

• Ctenamphiura Verrill, 1899

• Diamphiodia Fell, 1962

• Dougalopus A. M. Clark, 1970

• Gymnodia Fell, 1962

• Icalia Fell, 1962

• Microphiopholis Turner, 1985

• Monamphiura Fell 1962

• Monopholis Fell, 1962

• Nannophiura Mortensen, 1933

• Nudamphiura Tommasi, 1965

• Nullamphiura Fell, 1962

• Nullopholis Fell, 1962

• Ophiocnida Lyman, 1865

• Ophiomonas Djakonov, 1952

• Ophionema Lütken, 1869

• Ophionephthys Lütken, 1869

• Ophiophragmus Lyman, 1865

• Ophiostigma Lütken, 1856

• Pandellia Fell, 1962

• Paracrocnida Mortensen, 1940

• Paramphichondrius Guille & Wolff, 1984

• Paramphiura Koehler, 1895

• Silax Fell, 1962

• Triodia A.M. Clark, 1970

• Unioplus Fell, 1962

In addition, two extinct genera are known:

• † Deckersamphiura Jagt, 2000

• † Xanthamphiura Hess 1970

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 (Hendler and Bundrick, 2001).

References