''Linckia columbiae'' is a

species In biology, a species is the basic unit of Taxonomy (biology), 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 ...

of starfish in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Ophidiasteridae. It is found in the East Pacific where it ranges from

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...

(USA) to northwest

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

, including offshore islands such as the Galápagos.James, M.J., eds. (1991). ''Galápagos Marine Invertebrates: Taxonomy, Biogeography, and Evolution in Darwin's Islands.'' pp. 349. Topics in Geobiology. Common names include fragile star, Pacific comet sea star and variable sea star.

Description

''Linckia columbiae'' can grow to 10 cm (4 in) across and varies greatly in colour and shape and even the number of rays. Writing in 1904, Monks stated,

"In over 400 specimens examined not more than four were symmetrical, and no two were alike ... The normal number of rays is five, but some specimens have only one, while others have four, six, seven or even nine."

The disc is small with one or two

madreporite The madreporite is a light colored calcareous opening used to filter water into the water vascular system of echinoderms. It acts like a pressure-equalizing valve. It is visible as a small red or yellow button-like structure, looking like a sma ...

s, usually oval and variable in size. The long cylindrical rays have blunt, triangular points that turn up slightly at the tip. The surface is covered in hemispherical granules which are larger near the

ambulacral Ambulacral is a term typically used in the context of anatomical parts of the phylum Echinodermata or class Asteroidea and Edrioasteroidea. Echinoderms can have ambulacral parts that include ossicles, plates, spines, and suckers. For example, sea ...

grooves. There are two rows of ambulacral plates which distinguishes this species from the very similar '' Linckia guildingi'' which has three rows. The colour is generally mottled grey and red and there are a number of rows of tiny yellow stars running longitudinally down each ray.

Distribution and habitat

''Linckia columbiae'' is found in the East Pacific where it ranges from San Pedro,

(USA) and the

Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja C ...

(Mexico) to northwest

. It is also found at offshore East Pacific islands such as the Galápagos,

Clarion Island Isla Clarión, formerly called Santa Rosa, is the second largest, westernmost and most remote of Mexico's Revillagigedo Islands. The island is located west of Socorro Island and over from the Mexican mainland. It has an area of and three p ...

and

Cocos Island Cocos Island ( es, Isla del Coco) is an island in the Pacific Ocean administered by Costa Rica, approximately southwest of the Costa Rican mainland. It constitutes the 11th of the 13 districts of Puntarenas Canton of the Province of Puntarena ...

. It is found on rocks in the intertidal zone at depths down to about 150 m (500 ft).''Linckia columbiae''
Charles Darwin Foundation: Galapagos Species Checklist. Retrieved 2011-10-02.

Biology

This species often undergoes

autotomy Autotomy (from the Greek ''auto-'', "self-" and ''tome'', "severing", αὐτοτομία) or self-amputation, is the behaviour whereby an animal sheds or discards one or more of its own appendages, usually as a self-defense mechanism to elude ...

, a process where one or more rays becomes detached. The animal remains stationary while the ray, using its

tube feet Tube feet (technically podia) are small active tubular projections on the oral face of an echinoderm, whether the arms of a starfish, or the undersides of sea urchins, sand dollars and sea cucumbers; they are more discreet though present on bri ...

for purchase, pulls and twists itself away from the disc until the tissue connecting the two breaks. The separated ray is known as a "comet" and a new disc and a number of new rays start to grow on the damaged surface, a process that takes about six months to complete.

References

External links

* {{Taxonbar, from=Q2211529 Linckia Animals described in 1840