echinoderms. Mature individuals of can reach up to 500 mm in diameter. has thin spines that range from 300-400 mm in length and can be up to four times the diameter of the test (skeleton formed inside the body). The spines are thin, hollow, and break easily. The test is rigid and there is a reduced amount of soft tissue in the body wall as compared to other species in the family Diadematidae.is a regular (round) urchin, and displays the pentamerism of
The test and spines of a mature adult are typically black, but lighter colored spines may be intermixed, and in rare cases the urchin will be almost entirely white. The spines of juveniles are always banded with black and white. When the urchin dies, the spines falls off and the test remains.
At the base of the urchin are branched tentacles called tube feet, which help in gathering food, respiration, locomotion, and mucous production. (Banister and Campbell, 1985; Nichols and Cooke, 1971; Hendler, et al., 1995)
The fertilized egg has two forms: the blastula and the gastrula. These swim close to the surface of the water with the aid of cilia, and can be dispersed quite far, depending on currents. These larvae are known as the echinopluteus, and can remain in the larval stage for an average of 4-6 weeks. As the larvae mature, a vestibule is created in what will be the oral side of the urchin. Tentacles grow from this opening, on which suction areas eventually emerge. When the tentacles have suckers, they are primary poda, which serve as locomotive tools when the larva sinks to the ocean floor. At this point the skeletal plates begin to develop. When the 5 ambulical plates are developed and the terminal plate lies next to the genital plates, the urchin is fully developed, though it will continue to grow for the rest of its life. (Grzimek, 1972)
Some populations of (Grzimek, 1972)have been observed to congregate during their spawning season. There is no mating of individuals as fertilization and gestation occur in the open water.
The spawning ofappears to be connected to the lunar calendar. During the summer season, the egg and sperm are released once during each lunar month. This spawning period is dependant upon temperature; populations in different hemispheres may spawn at different times depending on when the warm season occurs.
The egg and sperm are released into the water where they are fertilized and develop into the larval echinopluteus. Egg size has also been observed to change during the month. Spawning occurs when the eggs are largest. (Anonymous, 1967; Grzimek, 1972; Hendler, et al., 1995)
There is no parental involvement post-spawning.
The lifespan of (Grzimek, 1972)is closely related to temperatures and food availability. Populations in warmer climates tend to have a quicker rate of development and shorter lifespan than those in colder climates.
Extremely sensitive to light,remains in darker areas, like crevices in the reef, during the day, and emerges at night to feed. Groups of individuals can be found in open areas, and densities can reach up to 20 per square meter. This group size corresponds to the abundance of predators in the area.
The gonads of sea urchins are considered a delicacy in many coastal regions, butis not one of the more preferred species.
Renee Sherman Mulcrone (editor).
Erin Puckett (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.
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.
an animal that mainly eats meat
uses smells or other chemicals to communicate
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
fertilization takes place outside the female's body
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
An animal that eats mainly plants or parts of plants.
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.
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.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
an animal that mainly eats all kinds of things, including plants and animals
generates and uses light to communicate
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).
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.
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
Anonymous, 1967. The Larousse Encyclopedia of Animal Life. Verona, Italy: McGraw-Hill Book Company.
Banister, K., A. Campbell. 1985. The Encyclopedia of Aquatic Life. New York: Facts of File Publishing.
Bruckner, A., R. Bruckner. 1998. Rapid-wasting disease: pathogen or predator?. Science, 279: 2023-2025.
Carson, R. 1955. The Edge of the Sea. Boston: Houghton Mifflin Company.
Carthy, J. 1958. An Introduction to the Behaviour of Invertebrates. New York: The MacMillian Company.
Grzimek, B. 1972. Grzimek's Animal Life Encyclopedia. New York: Van Norstand Reinhold Company.
Hendler, G., J. Miller, D. Pawson, P. Kier. 1995. Sea Stars, Sea Urchins, and Allies: Echinoderms of Florida and the Caribbean. Washington: Smithsonian Institution Press.
Meinkoth, N. 1984. The Audubon Society Field Guide to North American Seashore Creatures. New York: Alfred A. Knopf, Inc..
Nichols, D., J. Cooke. 1971. The Oxford Book of Invertebrates. Oxford: Oxford University Press.
Waller, G. 1996. SeaLife: A Complete Guide to the Marine Environment. Washington D.C.: Smithsonian Institution Press.