Linckia columbiae
Encyclopedia
Linckia columbiae is a species
of starfish in the family
Ophidiasteridae
that is found off the coast of California and adjacent areas of the semi-tropical north east Pacific Ocean. Common names include the fragile star, the Pacific comet sea star and the variable sea star.
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 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.
, a process where one or more rays becomes detached. The animal remains stationary while the ray, using its tube feet
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.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of starfish in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Ophidiasteridae
Ophidiasteridae
Ophidiasteridae is a family of sea stars with about 30 genera. Occurring both in the Indo-Pacific and Atlantic oceans, ophidiasterids are greatest in diversity in the Indo-Pacific...
that is found off the coast of California and adjacent areas of the semi-tropical north east Pacific Ocean. Common names include the fragile star, the Pacific comet sea star and the variable sea star.
Description
Linckia columbiae can grow to 10cm (4in) 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
Madreporite
The madreporite is a lightcolored calcerous 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 small wart, on the aboral surface of the central disk of a...
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 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 off the Pacific coast of California as far north as San Diego and San Pedro, and also in Columbia and the Galapagos Islands. It is found on rocks in the intertidal zone at depths down to about 150m (500ft).Biology
This species often undergoes autotomyAutotomy
Autotomy or self amputation is the act whereby an animal severs one or more of its own appendages, usually as a self-defense mechanism designed to elude a predator's grasp...
, a process where one or more rays becomes detached. The animal remains stationary while the ray, using its tube feet
Tube feet
Tube feet are the many small tubular projections found most famously on the oral face of a sea star's arms, but are characteristic of the water vascular system of the echinoderm phylum which also includes sea urchins, sand dollars and sea cucumbers and many other sea creatures.Tube feet function in...
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.