Linckia guildingiicommon comet star

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Geographic Range

Linckia guildingii is found in the Atlantic Ocean from Florida to Brazil, and around the Caribbean islands. It is also found in Australia (the Great Barrier Reef). Linckia guildingii usually inhabits shallow depths of about 1 meter, but has been found at a depth of over 100 meters. (Charonia Research, 1997; Hendler, 1995)

Habitat

Linckia guildingii primarily lives on the hard, flat bottom of coral reefs, but may also be found on slopes and sandy regions. Usually it is hidden, but may be exposed. (Charonia Research, 1996a; Hendler, 1995)

  • Range depth
    1 to 100 m
    3.28 to 328.08 ft

Physical Description

Linckia guildingii has 4-7 cylindrical arms of uneven length (up to 22 cm long). It is comet shaped (a star with a long tail) which is caused by its asexual mode of reproduction. This tail is the longest arm that came from the parent, while the "star" is composed of smaller, regenerated arms. However, this species may have a more symmetrical star shape at a different stage. Coloration changes with maturity. The adult is uniform and characteristically gray. Reddish brown, yellowish brown, tan, or violet adults also occur. Juveniles, however, are mottled white, gray, purple, violet, red or brown. (Charonia Research, 1997; Clark, 1977; Hendler, 1995)

  • Range length
    22 (high) cm
    8.66 (high) in

Development

Reproduction

Both sexual and asexual reproduction occur in this species; however, asexual reproduction is the dominant form. Arms voluntarily detach to form a new individual (known as autotomy). The new "daughter" has an identical genetic makeup to the parent.

In sexual reproduction, the sexes are separate. The females release many eggs. They are colorless and about 0.1 mm in diameter. The eggs are negatively buoyant upon leaving the female's gonopores (found on the arms). The development of larva is planktotrophic, meaning the larvae primarily survives by feeding on plankton.

Males have serially arranged gonads, with each arm containing several gonoducts. The gonads are particularly dominant before they spawn. At this time, gametes are released in the water, resulting in external fertilization. Some research has been done on the effect of the hormone 1-methyl adenine. When injected with the hormone, the starfish released their gametes, usually within three hours. The results varied depending on proximity to the natural mating season. For L. guildingii, the peak was in mid-summer in Australia (December). (Charonia Research, 1996b; Charonia Research, 1996c; Hendler, 1995; Meinkoth, 1981)

  • Parental Investment
  • no parental involvement

Behavior

This is a bottom dwelling species that moves from its cover to feed. It usually stays hidden to avoid predation by fish. (Hendler, 1995)

Food Habits

Linckia guildingii everts it stomach which excretes digestive juices to break down foods externally. Some food may be gathered from dead fish. However, the primary food source is from epibenthic felt (made up of protozoans, algae, and bacteria). Hard surfaces like coral-rock and sand are covered with a layer of this organic material. Linckia guildingii was proposed to be a filter (ciliary) feeder, and s generally thought to be a detritivore (eating felt). Linckia guildingii has a smaller cardiac stomach (large oral chamber) and larger rectal caeca (small outpocketings in in the intestine) when compared with other species. (Charonia Research, 1996a; Grzimek, 1972; Jangoux and Lawrence, eds., 1982)

  • Plant Foods
  • algae

Economic Importance for Humans: Positive

Only small economic benefit is gained through the sales of L. guildingii. They may be purchased as pets for aquariums and are sold under the common name "comet stars."

Economic Importance for Humans: Negative

Linckia guildingii causes no negative effects on the economy.

Conservation Status

Some conservation efforts have recently been started in Puerto Rico and the U.S.Virgin Islands. In 1999 a Marine Conservation District (MCD) was established that prohibits fishing or anchoring of fishing vessels in an area around St. Thomas and the U. S. Virgin Islands. Numerous reef animals are being protected from pollution and harvest for aquarium sale. (Department of Commerce and National Oceanic and Atmospheric Administration, 1999; Department of Commerce and National Oceanic and Atmospheric Administration, 1999)

Other Comments

Linckia guildingii and Ophidiaster guildingii are two similar species that are often confused due to coloration and location. Ophidiaster guildingi, however, has arms of equal length. They also have 15 pores per papular area, and L. guildingii can have up to 30. (Hendler, 1995)

Contributors

Renee Sherman Mulcrone (editor).

Adrianne Stropes (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

asexual

reproduction that is not sexual; that is, reproduction that does not include recombining the genotypes of two parents

carnivore

an animal that mainly eats meat

coastal

the nearshore aquatic habitats near a coast, or shoreline.

detritivore

an animal that mainly eats decomposed plants and/or animals

detritus

particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

filter-feeding

a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

radial symmetry

a form of body symmetry in which the parts of an animal are arranged concentrically around a central oral/aboral axis and more than one imaginary plane through this axis results in halves that are mirror-images of each other. Examples are cnidarians (Phylum Cnidaria, jellyfish, anemones, and corals).

reef

structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

scavenger

an animal that mainly eats dead animals

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

References

Charonia Research, 1996a. "Coral Reef Starfish, Chapter 3: Habitat" (On-line). Accessed 07/15/04 at http://www.charonia.com/charonia/chap3.htm.

Charonia Research, 1996c. "Coral Reef Starfish, Chapter 6: Sexual Reproduction" (On-line). Accessed 07/15/04 at http://www.charonia.com/charonia/chap6.htm.

Charonia Research, 1996b. "Coral Reef Starfish, Chapter 7: Asexual Reproduction" (On-line). Accessed 07/15/04 at http://www.charonia.com/charonia/chap7.htm.

Charonia Research, 1997. "Starfish species: *Linckia guildingii*" (On-line). Accessed 07/15/04 at http://www.charonia.com/charonia/species.htm.

Clark, A. 1977. Starfishes and Related Echinoderms. New Jersey: T.F.H.Publications, Inc., Ltd..

Department of Commerce, , National Oceanic and Atmospheric Administration. 1999. "Coral Reef Resources of Puerto Rico and the U.S. Virgin Islands; Initial Regulations; Federal Register 64 (213): 60132" (On-line). Accessed April 11, 2003 at http://www.epa.gov/fedrgstr/EPA-IMPACT/1999/November/Day-04/i28830.htm.

Grzimek, B. 1972. Grzimek's Animal Life Encyclopedia. New York: Van Nostrand Reinhold Company.

Hendler, G. 1995. Sea Stars, Sea Urchins, and Allies: Echinoderms of Florida and he Caribbean. Washington: Smithsonian Institution.

Jangoux, M., J. Lawrence, eds.. 1982. Echinoderm Nutrition. Rotterdam, Netherlands: A.A.Balkema.

Meinkoth, N. 1981. The Audobon Society Field Guide to North American Seashore Creatures. New York: Alfred A. Knopf, Inc..