Luidia alternata

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Geographic Range

Luidia alternata can be found from North Carolina down to Argentina. Although they concentrate on the coasts of Mississippi, Texas, and Mexico, L. alternata are also seen in the Caribbean and off of Florida's coast.

Habitat

These sea stars occur in sandy and muddy sediment in 3-50 meters of water.

Physical Description

Luida alternata usually reaches 20 cm from arm to arm but some may increase to a diameter of 40 cm. Its dorsal side is white or cream-colored with bands of dark green, purple, black or brown scattered on it. Its ventral surface is yellow with bright orange tube feet. They have five straplike arms fringed with slender spines. They appear fragile with the rows of paxillae irregularly arranged. The paxillae near the arm margins are larger than the midline and they hold a single long, pointed erect spine surrounded by small spinelets.

Reproduction

The ovaries of a female are pale salmon and contains egg cells about 1.9 mm in diameter. Female stars release their eggs into the water when they detects the presence of sperm, and vice versa for males. The triggers to begin the process are not known. The eggs that are fertillized develop into a free-swimming bilaterally symmetrical larvae called a bipinnaria. After about a month the 2mm long bipinnaria settles to the bottom and metamorphoses into the radially symmetric adult form.

Behavior

The most well-known behavior this sea star as well as others hold is its ability to regenerate severed or voluntarily automized arms. This form of regeneration is important for it can lead to asexual reproduction in the larvae stage.

Food Habits

L. alternata usually preys on other echinoderms like brittle stars, but on occasion they consume dead bait thrown overboard by fishermen. Since it is a common inhabitant of scallop beds off the Carolina coast, it usually preys on small individuals of the sea star species Astropecten articulatus. Because their tube feet lack the suckers needed to open bivalves, they swallow their prey whole, then regurgitate the undigestable portions.

Economic Importance for Humans: Positive

Since this species feeds on other seastars, it may be beneficial to shellfish fisheries because it eats other sea stars, some of which eat shellfish. Also, L. alternata is often used for eductional study.

Conservation Status

Contributors

Monica Verma (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.

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benthic

Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.

ectothermic

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

native range

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

References

Cooke, J., D. Nichols. 1979. Oxford Bood of Invertebrates. Oxford: Oxford University Press.

Fotheringham, N., S. Brunenmeister. January 1989. Beachcomber's Guide to Gulf Coast Marine Life. Houston, Texas: Gulf Publishing Company.

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

Hendler, G., J. Miller, D. Pawson, P. Kier. 1995. Sea Stars, Sea Urchins, and Allies. Washington and London: Smithsonian Institution Press.