Brittle stars belong to Class Ophiuroidea (Phylum Echinodermata) and have radial symmetry, with five elongate, skinny arms extending from their central disc, or body.
The lava rocks at Axial Seamount are typically covered with many members of the brittle star species Spinophiura jolliveti. Lacking a common name, we refer to this very abundant species as the Spinophiura Brittle Star. This species has the classic brittle star features described above. All organs are in this main body disk, and the mouth is comprised of 5 toothed jaws on the underside of the disk. The flexible arms are used for locomotion. They move fairly rapidly, because they do not depend on tube feet as does their sister group the sea stars. Instead, brittle stars use their arms to quickly propel themselves along the seafloor. This species’ arms reach up to 60 cm.
(Contributed by Jesse Turner, University of Washington, VISIONS 14, Leg 1)
Stöhr, S., O'Hara, T.D., & Thuy, B. 2012. Global diversity of brittle stars (Echinodermata: Ophiuroidea). PLoS ONE 7 (3): e31940. http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031940
Stöhr, S. & Segonzac, M. 2006. Two new genera and species of ophiuroid (Echinodermata) from hydrothermal vents in the East Pacific. Species Diversity 11 (1): 7-32.
This brittle star is extremely common at the base of Axial Seamount. It may also be a Spinophiura jolliveti, but images do not allow for a clear identification at this time. Their central disc is somewhat purple in color, and has been observed to expand into a cone (see video) when the organisms are stressed and combative!
This species (center) may be different from the much more common Spinophiura jolliveti, as its central disc has a different appearance. Brittle Star identification to the species level is often not possible using photography alone.