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

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of marine invertebrate in the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

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 an ...

. 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 describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Thi ...

(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 Octocorallia, along with Hexacorallia, is one of the two extant classes of Anthozoa. It comprises over 3,000 species of marine and brackish animals consisting of colonial polyps with 8-fold symmetry, commonly referred informally as "soft cora ...

or gorgonians.

Biology

''Ophiothrix suensoni'' is a

detritivore Detritivores (also known as detrivores, detritophages, detritus feeders or detritus eaters) are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). There are many kinds of invertebrates, ...

and

suspension feeder Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a spec ...

. 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 that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

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 Dioecy ( ; ; adj. dioecious, ) is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is ...

. 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 Echinoderms of Brazil Echinoderms of the Atlantic Ocean Echinoderms described in 1856