Diadema antillarumlong-spined sea urchin

Ge­o­graphic Range

Di­adema an­til­larum is found in the shal­low wa­ters of the At­lantic Ocean, in the Ba­hamas, and the West­ern At­lantic from east­ern Florida to Brazil. In the East­ern At­lantic D. an­til­larum is found in Madeira, the Gulf of Guinea, and the Ca­nary, Cape Verde, and Annabon is­lands. (Hendler, et al., 1995)

Habi­tat

Di­adema an­til­larum fa­vors quiet wa­ters, and is found most often in coral reefs. This species can also be found in tur­tle grass beds and on rock bot­toms. (Hendler, et al., 1995)

  • Aquatic Biomes
  • reef
  • Range depth
    0 to 400 m
    0.00 to 1312.34 ft

Phys­i­cal De­scrip­tion

Di­adema an­til­larum is a reg­u­lar (round) urchin, and dis­plays the pen­tamerism of echin­o­derms. Ma­ture in­di­vid­u­als of D. an­til­larum can reach up to 500 mm in di­am­e­ter. Di­adema an­til­larum 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.

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)

De­vel­op­ment

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)

Re­pro­duc­tion

Some pop­u­la­tions of D. an­til­larum have been ob­served to con­gre­gate dur­ing their spawn­ing sea­son. There is no mat­ing of in­di­vid­u­als as fer­til­iza­tion and ges­ta­tion occur in the open water. (Grz­imek, 1972)

The spawn­ing of D. an­til­larum ap­pears 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)

  • Breeding interval
    Spawning is temperature dependent.
  • Breeding season
    In summer, eggs and sperm are released each lunar month.

There is no parental in­volve­ment post-spawn­ing.

  • Parental Investment
  • pre-fertilization
    • provisioning

Lifes­pan/Longevity

The lifes­pan of D. an­til­larum 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. (Grz­imek, 1972)

  • Average lifespan
    Status: wild
    6 years
  • Typical lifespan
    Status: wild
    4 to 8 years

Be­hav­ior

Ex­tremely sen­si­tive to light, D. an­til­larum 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.

A very ac­tive urchin, D. an­til­larum has a high re­ac­tiv­ity and sen­si­tiv­ity to changes in light and water dis­tur­bances. The urchin will wave its spines in the di­rec­tion of the up­set­ting oc­curence, and re­treat to shel­tered areas quickly, if need be. (Ban­is­ter and Camp­bell, 1985; Hendler, et al., 1995)

Com­mu­ni­ca­tion and Per­cep­tion

Di­adema an­til­larum has a highly de­vel­oped light sen­si­tiv­ity. When a shadow ap­pears, the urchin waves its spines in the di­rec­tion of the shadow and moves away from the shadow, often into a more pro­tected area. In this sense, D. an­til­larum can al­most 'see' preda­tors. It is not known how in­di­vid­u­als com­mu­ni­cate with each other to ag­gre­gate. (Waller, 1996)

Food Habits

Di­adema an­til­larum grazes on the algal turf of coral reefs pri­mar­ily dur­ing the night. Foods eaten in­clude algal turf, young corals and zoan­thids. (Grz­imek, 1972; Hendler, et al., 1995)

  • Animal Foods
  • aquatic or marine worms
  • cnidarians
  • other marine invertebrates
  • zooplankton
  • Plant Foods
  • algae

Pre­da­tion

The spines of Di­adema an­til­larum are brit­tle and will frag­men­tize if wounded. The pieces are dif­fi­cult to re­move, and often cause in­fec­tions as they carry bac­te­ria. The mu­cous coat­ing of the spines, nor­mally used to kill or­gan­isms that live in the spines, car­ries a mild poi­son that also aids in de­ter­ring smaller preda­tors. Di­adema an­til­larum has been ob­served to gather in groups as an added pro­tec­tion. (Car­son, 1955; Grz­imek, 1972; Hendler, et al., 1995; Waller, 1996)

  • Known Predators
    • queen triggerfish (Balistes vetula)
    • Caribbean spiny lobsters (Panularis argus)
    • Caribbean helmets (Cassis turberosa)
    • two species of toadfish (Antennariidae)

Ecosys­tem Roles

Di­adema an­til­larum feeds on the algal turf of the coral reefs. The algal turf grows rapidly, and with­out the urchin's con­trol, can de­stroy the reefs. Di­adema an­til­larum clears the reefs, mak­ing room for coral lar­vae to set­tle and grow. How­ever, the urchin ac­tu­ally wears away at the cal­cium car­bon­ate of the reef, too. (Hendler, et al., 1995)

Com­men­sal/Par­a­sitic Species

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

The go­nads of sea urchins are con­sid­ered a del­i­cacy in many coastal re­gions, but D. an­til­larum is not one of the more pre­ferred species.

Sea urchin eggs are used ex­ten­sively in em­bry­olog­i­cal re­search. (Ban­is­ter and Camp­bell, 1985; Grz­imek, 1972)

  • Positive Impacts
  • food
  • research and education

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

The spines of D. an­til­larum are very sharp and can eas­ily pierce skin, shoes, and wet­suits. Con­tact with a spine is not ex­tremely painful, but the shat­ter­ing of the spine leaves or­ganic ma­te­r­ial in the wound that can cause in­tensely painful in­fec­tions. The poi­so­nous mu­cous seems to have very lit­tle ef­fect on hu­mans. (Car­son, 1955; Hendler, et al., 1995)

  • Negative Impacts
  • injures humans
    • bites or stings

Con­ser­va­tion Sta­tus

Other Com­ments

In 1983 D. an­til­larum ex­pe­ri­enced a mas­sive die-off all across the Caribbean; some areas lost up to 97% of ma­ture in­di­vid­u­als. The die-off is thought to be due to a wa­ter-borne pathogen that has not yet been iden­ti­fied. The great re­duc­tion of D. an­til­larum in the reefs caused an ex­treme in­crease in the algal cover, and thus a re­duc­tion of lar­val coral set­tle­ment. Mi­croal­gae has be­come more abun­dant in the time since the die-off; the greater amount of algae al­lows the reefs to sup­port a greater num­ber of her­biv­o­rous fish, which can re­sult in more dam­age to the reefs. (Bruck­ner and Bruck­ner, 1998; Hendler, et al., 1995)

Con­trib­u­tors

Renee Sher­man Mul­crone (ed­i­tor).

Erin Puck­ett (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

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

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

food

A substance that provides both nutrients and energy to a living thing.

herbivore

An animal that eats mainly plants or parts of plants.

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.

nocturnal

active during the night

omnivore

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

photic/bioluminescent

generates and uses light to communicate

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.

seasonal breeding

breeding is confined to a particular season

sexual

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

tactile

uses touch to communicate

tropical

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

visual

uses sight to communicate

zooplankton

animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)

Ref­er­ences

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.