Classification
Kingdom: Animalia
Phylum: Echinodermata
Class: Echinoidea
Order: Diadematoida
Family: Diadematidae
Genus: Diadema
Phylum: Echinodermata
Class: Echinoidea
Order: Diadematoida
Family: Diadematidae
Genus: Diadema
Common Name
Diadema antillarum
Morphology
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.
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.
Biolgy
Their extremely sharp spines can crumble after penetration into the skin, inflicting painful wounds (Sterrer 1986). They will not try to hurt you, unless you grab them; this is a defensive mechanism of Diadema that protects them from predation. Predators include gastropods, crabs, starfish (within their own phylum!), and fish including surgeonfish, porcupine fish, and wrasses.
Distribution Map
Importace:Ecological and Economical
Medical Research
Sea urchin larvae are used in embryology and molecular biology research, in addition to biomedical research.
Seafood
In some countries, the gonads of some species of sea urchins are eaten (Sterrer 1986). However, they are not eaten in Bermuda. Diadema antillarum have indirect commercial importance in Bermuda, due to their importance in the marine food web.
In order to support high concentrations of D. antillarum, the substrates on which they live must have fairly high productivity in order to support the nutritional needs of the urchins. In his study on urchin populations in St. Croix, Ogden (1973) found that the biodiversity, based on the diversity of algal species, was greater in the patch reef with predation by urchins. In contrast, the patch reef lacking a Diadema population was dominated by several species, ultimately reducing biodiversity.
Sea urchin larvae are used in embryology and molecular biology research, in addition to biomedical research.
Seafood
In some countries, the gonads of some species of sea urchins are eaten (Sterrer 1986). However, they are not eaten in Bermuda. Diadema antillarum have indirect commercial importance in Bermuda, due to their importance in the marine food web.
In order to support high concentrations of D. antillarum, the substrates on which they live must have fairly high productivity in order to support the nutritional needs of the urchins. In his study on urchin populations in St. Croix, Ogden (1973) found that the biodiversity, based on the diversity of algal species, was greater in the patch reef with predation by urchins. In contrast, the patch reef lacking a Diadema population was dominated by several species, ultimately reducing biodiversity.
Interesting Facts
In order for their eggs to be fertilized, male and female Diadema must release their eggs and sperm into the water at the same time (Simon 1973). To make sure this happens, the male or female sea urchin sends a chemical substance into the water, and the smell of this substance makes every sea urchin in the vicinity release its eggs or sperm (Simon 1973). This mass release increases the chance that the eggs will be fertilized (Simon 1973).
Shortly after fertilization, the blastula is free-swimming (Sterrer 1986). The gastrula develops into a planktonic larval stage, known as echinopluteus, with a laterally compressed shape, bearing 4-6 pairs of arms supported by calcareous spicules (Sterrer 1986). After a few weeks, the echinopluteus sinks to the substrate where it rapidly metamorphoses into a juvenile urchin. The metamorphoses can occur within one hour (Sterrer 1986).
The mass-mortality of Diadema antillarum occurred over a two-year period from 1983-1984 (Lessios 1988). The lack of geographic isolation of the 1980s combined with a rapid unprecedented decline of the D. antillarum population, with populations reduced to at least 7% and often less than 2% of their former numbers over the course of two years (Knowlton 2001), led me to believe that this species may have been an important factor in the rapid decline of coral populations in the 1980s.
Shortly after fertilization, the blastula is free-swimming (Sterrer 1986). The gastrula develops into a planktonic larval stage, known as echinopluteus, with a laterally compressed shape, bearing 4-6 pairs of arms supported by calcareous spicules (Sterrer 1986). After a few weeks, the echinopluteus sinks to the substrate where it rapidly metamorphoses into a juvenile urchin. The metamorphoses can occur within one hour (Sterrer 1986).
The mass-mortality of Diadema antillarum occurred over a two-year period from 1983-1984 (Lessios 1988). The lack of geographic isolation of the 1980s combined with a rapid unprecedented decline of the D. antillarum population, with populations reduced to at least 7% and often less than 2% of their former numbers over the course of two years (Knowlton 2001), led me to believe that this species may have been an important factor in the rapid decline of coral populations in the 1980s.
Vocabulary
pentamerous= radial sysmmetry -sysmmetry based of five oarts
endoskeleton= a skeleton under the external surface of animal
tube feet= any of the external muscular extensions of the water vascular system of echinoderms
ampullae= each of the muscular sacs that extend inside the body opposite the tube feet of echinoderms
madre porite= a porous olate that connects the water vacular system of echinodermsto the exterior
endoskeleton= a skeleton under the external surface of animal
tube feet= any of the external muscular extensions of the water vascular system of echinoderms
ampullae= each of the muscular sacs that extend inside the body opposite the tube feet of echinoderms
madre porite= a porous olate that connects the water vacular system of echinodermsto the exterior