''Linckia guildingi'', also called the common comet star, Guilding's sea star or the green Linckia, 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), ...

sea star Starfish or sea stars are Star polygon, star-shaped echinoderms belonging to the class (biology), class Asteroidea (). Common usage frequently finds these names being also applied to brittle star, ophiuroids, which are correctly referred to ...

reported from the shallow waters of the tropical

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

and the

Caribbean Sea The Caribbean Sea is a sea of the Atlantic Ocean, North Atlantic Ocean in the tropics of the Western Hemisphere, located south of the Gulf of Mexico and southwest of the Sargasso Sea. It is bounded by the Greater Antilles to the north from Cuba ...

Taxonomy

Recent studies have indicated that ''Linckia guildingi'' may represent several

cryptic species In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

. Examination of the mtDNA showed that there are two

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

s within ''L. guildingi''. The divergence between these implies that they separated over a million years ago.

Distribution

This species was described from St Vincent's, (

Saint Vincent (Antilles) Saint Vincent is a volcanic island in the Caribbean. It is the largest island of the country Saint Vincent and the Grenadines and is located in the Caribbean Sea, between Saint Lucia and Grenada. It is composed of partially submerged volcanic ...

) in the Caribbean Sea.

Description

''L. guildingi'' has a small disc and usually 5 (occasionally 4 or 6) long cylindrical arms. The upper surface appears smooth but is in fact rough to the touch with low, firm nodules. Though this starfish is often green, it comes in a range of colours including various shades of brown, blue and dull red.

Biology

''L. guildingi'' sometimes exhibits

autotomy Autotomy (from the Greek ''auto-'', "self-" and ''tome'', "severing", αὐτοτομία) or 'self-amputation', is the behaviour whereby an animal sheds or discards an appendage, usually as a self-defense mechanism to elude a predator's grasp ...

, shedding one or more of its arms. In a study on Hawaii, it was found that autotomy happens less frequently than in the related species, ''Linckia multifora'', also found in these waters. In time the arm will regenerate and in both species, the detached arms, known as "comets", are capable of moving about independently and themselves developing into new individuals, a form of

asexual reproduction Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the f ...

. The process is quite slow, it taking 6 months for the

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 ...

to appear. At 10 months it became functional and the new arms had reached 10mm (0.4 in) long as shown in the image above.Autotomy and Regeneration in Hawaiian Starfishes
Retrieved 2011-09-25.

References

{{Taxonbar, from=Q2856487 guildingi Echinoderms of the Atlantic Ocean Starfish described in 1840 Taxa named by John Edward Gray