''Diadema'' is a genus of sea urchins of the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Diadematidae.

Characteristics

It is one of the most abundant, widespread, and ecologically important shallow water genera of tropical sea urchins. It is found in all tropical oceans, although is ubiquitous in the Indo-Pacific region, where it inhabits depths down to 70 m. However each species inhabits roughly separate areas of ocean. Diadema urchin

Speciation within the genus can be difficult to confirm, partly due to hybridisation, which is at least known to occur between '' Diadema savignyi'' and ''

Diadema setosum ''Diadema setosum'' is a species of long-spined sea urchin belonging to the family Diadematidae. It is a typical sea urchin, with extremely long, hollow spines that are mildly venomous. ''D. setosum'' differs from other '' Diadema'' with five, ...

''. The species vary in types of sea bed they inhabit, with ''Diadema savignyi'' inhabiting sandy beds and back

reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock o ...

where damaged; while ''Diadema setosum'' can also commonly be found among

seagrass Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the or ...

Fossil record

The fossil record of ''Diadema'' is extremely poor, consisting only of spines that possibly belong to the genus, some of which go back to the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

, 5 to 25 million years ago.

Species list

According to

World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive list of names of marine organisms. Content The content of the registry is edited and maintained by scientific specialis ...

Fossils

* ''

Diadema principeana Diadema is the term for diadem in most Romance languages, and in English may refer to: * Diadema, São Paulo, a city in São Paulo state, Brazil * ''Diadema'' (sea urchin), a genus of sea urchin belonging to the family Diadematidae * ''Diadema'' ...

'' Weisbord, 1934 † (fossil taxon,

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

from Cuba) * ''

Diadema vetus Diadema is the term for diadem in most Romance languages, and in English may refer to: * Diadema, São Paulo, a city in São Paulo state, Brazil * ''Diadema'' (sea urchin), a genus of sea urchin belonging to the family Diadematidae * ''Diadema'' ...

'' Lambert, 1931c † ( fossil taxon, first appeared in the

in North Africa)

References

Bibliography

* Nyawira A. Muthiga and Timothy R. McClanahan, "Diadema", ''in ''John M. Lawrence, ''Sea Urchins: Biology and Ecology'', London,

Elsevier Elsevier () is a Dutch academic publishing company specializing in scientific, technical, and medical content. Its products include journals such as '' The Lancet'', ''Cell'', the ScienceDirect collection of electronic journals, '' Trends'', ...

, 2013. *
Edge of reef
{{Taxonbar, from=Q4037290 Diadematidae Echinoidea genera Taxa named by John Edward Gray