Diadema antillarum
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| Long-spined sea urchin | ||||||||||||||
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 Diadema antillarum
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| Diadema antillarum (Philippi, 1845) |
Diadema antillarum also known as the lime urchin, black sea urchin or the long-spined sea urchin[citation needed], is a sea urchin of the Family Diadematidae. It has long black spines, and is the most abundant and important herbivore on the coral reefs of the western Atlantic and Caribbean basin. In this role it was the main grazer that maintained the balance between algae growth and destruction.
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[edit] Ecological Importance
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This section may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can (January 2008). |
In 1983 Diadema antillarum underwent mass mortality, with more than 97% of the urchins dying throughout the Caribbean and as far south as South America and north to the Bahamas. Since this time some Caribbean reefs have been overcome by micro-algae which stifles coral growth, it also has resulted in widespread coral disease. Recent studies done in Discovery Bay Jamaica and other locations suggest a massive comeback of the Diadema and great regeneration of the reefs.[citation needed]
Diadema antillarum is still in some places one of the most abundant, widespread, and ecologically important shallow water genera of tropical sea urchins. It is found in tropical oceans, particularly in the Indo-Pacific region, where it inhabits depths down to 70 m.
Thie black sea urchin consumes algae covering coral reefs in the western Atlantic Ocean, Caribbean, South America, and the Indo-Pacific area. When the sea urchins died due to an unknown disease, marine life in the western Atlantic Ocean, down to parts of South America, suffered a great deal. The heightened amount of lush algae stunted and even reversed the development of coral, the fish and plants living on the reefs then received less food and shelter. The reduced coral reefs with low marine life affect the tourism of small countries that depend on the natural beauty of their resources to attract and satisfy customers. Because tourism is a major part of the income in these countries, the decreased flow of guests stresses the economy. Help for the urchins is needed in order for the urchins to repopulate quickly.
Low-density populations, predators, and waves from high-powered storms impede the slow return 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 repoduction. 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. Saving and assisting the urchins requires research, volunteers, and commitment.
[edit] Anatomy
The Diadema antillarum has has a test, or shell, similar to most other ssea urchins. What distinguishes the Diadema is what grows off of it. there are, of course, it's spines. Most sea urchin spines are 1-3 cm long but the diadema's spines are normally around 10-12 cm long and can grow to an amazing 30 cm, the rest of the Daidema's anatomy is much like that of other sea urchins.
[edit] Lifestyle
Diadema mostly live form 1-10 meters in depth on coral reefs. They will often lodge themselves in a crevice so that only their spines can be seen, but other individuals who can't find a crevice, will roam free. The individual that can find a crevice usulally will roam about 1 metre from their crevice at night. The diadema is extaordinarily 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. But starving urchins have been known to become carnivorous.
[edit] Research
The research conducted for species Diadema antillarum, commonly known as the long-spined sea urchin, has yet to become in-depth. In 1983, this remarkable sea creature suffered a population decrease so severe that the overgrowth of algae on coral reefs has begun to effect many areas of marine and human life. Due to the limited research and resources, the recovery of the urchin is still in progress. In order to increase the speed of growth, research and projects need to focus on targeting the environmental issues, removing the impediments of the growth, and helping the widespread repopulation.
Diadema antillarum is significant in the growth of coral reefs and economies of small countries.
The urchins can be grown in laboratories, relocated, and aided by the artificial building of reefs. Diadema antillarum have shown that in many cases growth and reproduction in controlled environments is successful. Returning the matured invertebrate into the wild is less profitable for the urchin, but can still have a positive effect on the expansion and urchin density of the reef. If there is an area of high-density urchins, it is possible and highly successful to relocate urchins to other low-density reefs. Adding material such as concrete can help the expansion of coral, and provide more niches for the urchins to hide from predators, like larger fish. With these tips and volunteers, the population increase is inevitable and the shift back to coral dominated reefs from algal dominated reefs is enormously possible.
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