Thursday 26 June 2014

A new species of Brittle Star from the coast of northern Peru.

Brittle Stars (Ophiuroidea) are five-limbed Echinoderms superficially resembling Starfish (Asteroidea). Like Starfish they posses (usually) five limbs arranged around a central disk which houses the mouth and anus, but the limbs of Brittle Stars are clearly differentiated from the central disk and are articulated and used in movement, while those of a Starfish are nearly immobile, effectively forming rigid extensions of the central disk, and movement is achieved using tube feet on the underside of the animal.

In a paper published in the journal ZooKeys on 2 December 2013, Tania Pineda-Enríquez and Francisco Solís-Marín of the Laboratorio de Sistemática y Ecología de Equinodermos at the Instituto de Ciencias del Mar y Limnología at the Universidad Nacional Autónoma de México, Yuri Hooker of the Laboratorio de Biología Marina at the Universidad Peruana Caytano Heredia and Alfredo Laguarda-Figueras, also of the Laboratorio de Sistemática y Ecología de Equinodermos, describe a new species of Brittle Star from the coast of northern Peru.

The new species is placed in the genus Ophioderma and given the specific name peruana, meaning ‘from Peru’. It has a central disk reaching 42 mm in diameter on the largest specimens, and arms exceeding 120 mm in length. The central disk is covered in granular scales. The arms have larger scales, however these scales fragment into smaller, irregular portions, the underside of the arms are covered in conical, flattened, blunt-tipped spines.

Ophioderma peruana in life. Pineda-Enríquez et al. (2013).

Ophioderma peruana was found in the intertidal zone on Lobos de Afuera Island in Lambayeque, at a depth of 9 m off Quebrada Verde in El Ñuro and at a depth of 14 m on Hooker Reef off Punta Sal. 

Ophioderma peruana (C) aboral disc and basal portion of the arms (D) oral disc and basal portion of the arms (E) jaws (F) oral portion of the disc and pair of genital slits. Pineda-Enríquez et al. (2013).

Ophioderma peruana (A) basal portion of the arms with fragmented dorsal arm plates (B) dorsal arm plates fragmented in several pieces (C) ventral arm plates and tentacle scales (D) lateral view of the arm spines. Pineda-Enríquez et al. (2013).

See also…

Starfish (Asteroidea) are benthic marine Echinoderms found across the globe. They have a simple bodyplan, with a central disk that has the mouth on the underside, surrounded by (usually) five arms, each with a double row of tube feet underneath. The upper surface of the Starfish is covered by an articulated armoured exoskeleton made up of thousands of...

Sea Cucumbers (Holothuroidea) are a class of Echinoderms that have become elongated and worm-like, effectively becoming secondarily bilaterally symmetrical. Like all Echinoderms they have a calcareous exoskeleton, but this is greatly reduced, typically only occurring as ossicles within the epidermis. The muscle structure of Sea Cucumbers is instead supported by a layer of modified collegen that can be stiffened...

Crinoids are stalked Echinoderms, related to Starfish and Sea Urchins, but with a very different morphology. They are attached to by either by a stalk with a holdfast cemented to some hard substrate, of by a flexible stalk able to wrap itself around some object, typically a Coral or a Sponge. Above this grows an animal with a cup-like central body known as the calyx, surrounded by five branching arms, covered in long, flexible, tube feet which catch plankton and marine detritus and pass them to the mouth...

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