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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.
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.
Communication Channels: chemical
Other Communication Modes: photic/bioluminescent
Perception Channels: visual ; tactile ; chemical
US Federal List: no special status
CITES: no special status
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.
Development - Life Cycle: metamorphosis
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.
Negative Impacts: injures humans (bites or stings)
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.
Positive Impacts: food ; research and education
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.
Commensal/Parasitic Species:
Diadema antillarum grazes on the algal turf of coral reefs primarily during the night. Foods eaten include algal turf, young corals and zoanthids.
Animal Foods: aquatic or marine worms; cnidarians; other marine invertebrates; zooplankton
Plant Foods: algae
Primary Diet: carnivore (Eats non-insect arthropods, Eats other marine invertebrates); herbivore (Algivore); omnivore
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.
Biogeographic Regions: atlantic ocean (Native )
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.
Range depth: 0 to 400 m.
Habitat Regions: tropical ; saltwater or marine
Aquatic Biomes: reef
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.
Average lifespan
Status: wild: 6 years.
Typical lifespan
Status: wild: 4 to 8 years.
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.
Other Physical Features: ectothermic ; heterothermic ; radial symmetry
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.
Known Predators:
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.
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.
Breeding interval: Spawning is temperature dependent.
Breeding season: In summer, eggs and sperm are released each lunar month.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External )
There is no parental involvement post-spawning.
Parental Investment: pre-fertilization (Provisioning)
