Echinoecus

''Echinoecus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

crab Crabs are decapod crustaceans of the infraorder Brachyura (meaning "short tailed" in Greek language, Greek), which typically have a very short projecting tail-like abdomen#Arthropoda, abdomen, usually hidden entirely under the Thorax (arthropo ...

s that live in association with

sea urchin Sea urchins or urchins () are echinoderms in the class (biology), class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal zone to deep seas of . They typically have a globular body cove ...

s. Formerly considered

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

, the genus is now thought to contain three species: *''Echinoecus nipponicus'' Miyake, 1939 –

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

, on ''Heliocidaris crassispina'' (

Echinometridae The Echinometridae are a Family (biology), family of sea urchins in the class (biology), class Echinoidea. Characteristics All Echinometridae have imperforate tubercles and compound ambulacral plates.Pseudocentrotus depressus'' (

Strongylocentrotidae The Strongylocentrotidae are a family (biology), family of sea urchins in the order (biology), order Camarodonta. Genera References

Strongylocentrotidae, Echinoderm families {{echinoidea-stub ...

) *'' Echinoecus pentagonus'' (A. Milne-Edwards, 1879) –

East Africa East Africa, also known as Eastern Africa or the East of Africa, is a region at the eastern edge of the Africa, African continent, distinguished by its unique geographical, historical, and cultural landscape. Defined in varying scopes, the regi ...

and

Red Sea The Red Sea is a sea inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab-el-Mandeb Strait and the Gulf of Aden. To its north lie the Sinai Peninsula, the Gulf of Aqaba, and th ...

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

and

French Polynesia French Polynesia ( ; ; ) is an overseas collectivity of France and its sole #Governance, overseas country. It comprises 121 geographically dispersed islands and atolls stretching over more than in the Pacific Ocean, South Pacific Ocean. The t ...

, on '' Diadema savignyi'', '' D. setosum'', ''

Echinothrix calamaris ''Echinothrix calamaris'', known commonly as the banded sea urchin or double spined urchin among other vernacular names, is a species of sea urchin in the Family (biology), family Diadematidae. Description The banded sea urchin has a slightly ov ...

'' and '' E. diadema'' (

Diadematidae The Diadematidae are a family of sea urchins. Their tests are either rigid or flexible and their spines are long and hollow. * '' Astropyga'' Gray, 1825 **'' Astropyga radiata'' ( Leske, 1778), extant **'' Astropyga pulvinata'' (Lamarck, 1816), ...

), ''

Heterocentrotus mammillatus ''Heterocentrotus mamillatus'', commonly known as the slate pencil urchin, red slate pencil urchin, or red pencil urchin, is a species of tropical sea urchin from the Indo-Pacific region. Description This species is a large sea urchin, capp ...

'' (

Strongylocentrotidae The Strongylocentrotidae are a family (biology), family of sea urchins in the order (biology), order Camarodonta. Genera References

Strongylocentrotidae, Echinoderm families {{echinoidea-stub ...

) *''Echinoecus sculptus'' (Ward, 1934) –

Christmas Island Christmas Island, officially the Territory of Christmas Island, is an States and territories of Australia#External territories, Australian external territory in the Indian Ocean comprising the island of the same name. It is about south o ...

, on '' Colobocentrotus atratus'' (