''Ophiothrix suensoni'', Suenson's brittle star or the sponge brittle star, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of marine invertebrate in the order

Ophiurida The Ophiurida are an order of echinoderms within the class Ophiuroidea. It includes the vast majority of living brittle stars. Characteristics Ophiurida have bursae for respiration and excretion, and dorsal and ventral arm shields are present a ...

. It is found in the Caribbean Sea and Gulf of Mexico. It is included in the subgenus ''Acanthophiothrix'' making its full scientific name ''Ophiothrix (Acanthophiothrix) suensoni''.

Description

''Ophiothrix suensoni'' has a small central disc which is clearly demarcated from the five long thin arms. The arms can be up to long and the disc in diameter. The

aboral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

(upper) surface of the disc is covered with scales which are ornamented with long spines. The arms are cylindrical in cross section and the surface of the lateral scales bear long, sharp, transparent spines. There is a purple, deep red or black stripe running the length of the aboral surface of each arm. The colour of this brittle star is variable, being pale mauve, pink, yellow or red, and often the arms are a different hue from the disc.

Distribution and habitat

''Ophiothrix suensoni'' is a common species throughout the Caribbean Sea and Gulf of Mexico from Bermuda and Florida south to Venezuela and Brazil. It is found at depths ranging from . It is always associated with sponges such as the red tree sponge (''

Haliclona compressa ''Amphimedon compressa'', the erect rope sponge, red tree sponge, red tubular sponge, or red sponge is a demosponge found in southern Florida, the Caribbean Sea, and the Bahamas. It can be deep red, orange, brown, or black. Taxonomy The erect r ...

''), soft corals or gorgonians.

Biology

''Ophiothrix suensoni'' is a detritivore and suspension feeder. It hides during the day and emerges at night to feed. It climbs to a high point on its host sponge or sea rod and extends some of its arms to catch

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

and suspended particles floating past. It also feeds on the organic film that is found on the surface of its host. ''Ophiothrix suensoni'' is dioecious. Breeding takes place all year round but peaks in the late summer and autumn. The males have larger gonads than the females perhaps in order to increase the concentration of sperm in the vicinity of females as they do not synchronize their spawning.

References

{{Taxonbar, from=Q2960637 Ophiotrichidae Animals described in 1856