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)
In Panama this species been collected in the Caribbean from:
-Galeta Island (USNM E 26602, USNM E 26687, USNM E 28260, USNM E 38607; Centroid Latitude: 9.4067, Centroid Longitude: -79.8667)
Portobelo (USNM E 11402, USNM E 27448)
-Limon Bay, Colon (USNM 39448, USNM E 26606)
-3.5 miles North of the Piedras River (USNM E 18817)
-Miria Island, San Blas (USNM E 26686)
Mortensen, T. (1940). A monograph of the Echinoidea 3(1). Aulodonta. Copenhagen. 370 pp., 196 figures, 77 pls, pages: 269-275.
Lessios, H. A. (1988). Population dynamics of Diadema antillarum (Echinodermata: Echinoidea) following mass mortality in Panamá. Marine Biology 99: 515-526.
Lessios, H. A., Robertson, D. R. & Cubit, J. D. (1984). Spread of Diadema mass mortality through the Caribbean. Science 226: 335-337.
Lessios, H.A., Kessing, B.D. & Pearse, J.S. (2001). Population structure and speciation in tropical seas: global phylogeography of the sea urchin Diadema. Evol. 55: 955-975.
Coppard, S. E. & Campbell, A. C. (2004). Taxonomic significance of spine morphology in the echinoid genera Diadema and Echinothrix. Invertebrate Biology, 123 (4), 357-371.
Coppard, S. E. & Campbell, A. C. (2006a). Taxonomic significance of test morphology in the echinoid genera Diadema Gray, 1825 and Echinothrix Peters 1853 (Echinodermata). Zoosystema 28(1), 93-112.
Coppard, S. E. & Campbell, A.C. (2006b). Systematic significance of tridentate pedicellariae in the echinoid genera Diadema and Echinothrix. Invertebrate Biology 125(4), 363-378.
LSID urn:lsid:marinespecies.org:taxname:124332Centrechinus antillarum (Philippi, 1845) (transferred to Diadema)
Centrechinus setosus Jackson, 1912 (subjective junior synonym)
Cidaris (Diadema) antillarum Philippi, 1845 (transferred to Diadema)
Diadema antillarum, also known as the lime urchin, black sea urchin, or the long-spined sea urchin,[2] is a species of sea urchin in the family Diadematidae.
This sea urchin is characterized by its exceptionally long black spines.
It is the most abundant and important herbivore on the coral reefs of the western Atlantic and Caribbean basin. When the population of these sea urchins is at a healthy level, they are the main grazers which prevent algae overgrowth of the reef.
Diadema antillarum has a "shell," similar to most other sea urchins. What distinguishes the Diadema is the length of its spines. Most sea urchin spines are 1–3 cm, but the spines in this species are usually 10–12 cm in length, and can grow as long as 30 cm in very large individuals.
This species usually lives at 1–10 metres in depth on coral reefs. They will often lodge themselves in a crevice, so that only their spines can be seen, but individual urchins who can't find a suitable crevice will live in more exposed situations. Individuals that have been able to find a crevice usually will roam about one metre from their crevice at night during feeding. Diadema is very sensitive to light, and will often pick its crevice or resting place based on how much shade there is.
Diadema mostly eat algae, and sometimes seagrass. Starving urchins have been known to become carnivorous.
Diadema antillarum is still, in some tropical areas, one of the most abundant, widespread, and ecologically-important shallow-water sea urchins. It is found in the tropical Western Atlantic Ocean, including the Caribbean Sea, Gulf of Mexico and the northern and eastern coasts of South America (as far south as Brazil). It is also found in the East Atlantic at the Canary Islands and the Indian Ocean. This species is ecologically important because it consumes algae that can otherwise grow to such an extent that they can smother coral reefs. They live in holes that are in the reef.
In 1983, throughout the Caribbean faunal zone as far south as South America and north to the Bahamas, Diadema antillarum underwent mass mortality, with more than 97% of the urchins dying.[3] Since this time some Caribbean reefs have been overgrown by foliose macroalgae. This inhibits coral growth and has further compounded the ongoing decline of scleractinian corals. It also has an overall negative effect on coral reef resilience, which encompasses the ability of a system to resist and recover from changes stemming from perturbation events. Recent studies done in Discovery Bay, Jamaica,[4] and other locations[5] appear to show a massive comeback of Diadema, and great regeneration of the reefs. As of 2015 populations are densest in the eastern Caribbean at Jamaica, Barbados, Dominica, and Puerto Rico, while either remaining virtually stable at low values or showing small increases on the coast of Central America and in Cuba, Florida, the Bahamas, the Virgin Islands, and Curaçao. The highest rate of increase has been on the north coast of Jamaica, and the lowest in Florida, Cuba, and the Bahamas. Two populations, in Venezuela and the San Blas Islands, Panama, have actually continued to decline with time. In 2022, another die-off was reported in the Caribbean, specifically the U.S. Virgin Islands, Saba, and St. Eustatius.[6]
When the sea urchins died due to an unknown disease, the biodiversity of the marine life of the coral reefs suffered a great deal. The resulting lush algae growth stunted and even reversed the development of coral, and the fish and other animals living on the reefs declined in numbers due to less food and shelter.
The reduced biodiversity of the coral reefs affected tourism in several small countries, which depended on the natural beauty of their reefs to help attract visitors, and because tourism was a major part of the income for these countries, the decreased flow of guests stressed their economy.
Low-density populations, predators, and waves from high-powered storms tends to impede the repopulation of Diadema antillarum. In the fertilization process, male and female urchins excrete fluid to alert other urchins to respond by releasing their eggs and sperm in mass reproduction. With more gametes available, there is a higher chance of fertilization. However, in areas of low-population, a few sea urchins may not be enough to initiate fertilization. After fertilization, there is still a high chance that predators may consume the vulnerable juveniles. Because of the movement of water in powerful storms, urchins can get swept away from their habitat and expire. It is possible to aid the increase in population growth of the urchin with more research and volunteers.
Research on the species Diadema antillarum is still in its early stages. The urchins can be grown in laboratories and then relocated. Returning the mature individuals into the wild can have a positive effect on the urchin density of the reef. The increase in population can also be aided by the artificial building of reefs: material such as concrete can encourage the growth of coral, and provide more niches for the urchins to hide from predators such as larger fish.
When there are still some areas of high-density urchins, it is possible to relocate urchins to other, low-density reefs. With these methods and the help of volunteer workers, it seems that the shift back to coral-dominated reefs and away from algae-dominated reefs is possible.
Diadema with unusual grey spines at Snapper Ledge Diadema antillarum, also known as the lime urchin, black sea urchin, or the long-spined sea urchin, is a species of sea urchin in the family Diadematidae.
This sea urchin is characterized by its exceptionally long black spines.
It is the most abundant and important herbivore on the coral reefs of the western Atlantic and Caribbean basin. When the population of these sea urchins is at a healthy level, they are the main grazers which prevent algae overgrowth of the reef.
