Echinoecus pentagonus
Encyclopedia
The "sea urchin crab" Echinoecus pentagonus is a species
of crab
in the family
Pilumnidae
found from the Red Sea
and East Africa
to French Polynesia
and the Hawaiian Islands
. This crab is a parasite that lives in the rectum
of a sea urchin
. In Hawaii
, it chooses only Echinothrix calamaris
, leaving few of these urchins unpopulated. Its curved and pointed carapace
reaches only 0.5 inches (1.3 cm) in width.
Taxonomic synonyms
of E. pentagonus include:
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Pilumnidae
Pilumnoidea
Pilumnoidea is a superfamily of crabs, whose members were previously included in the Xanthoidea. The three families are unified by the free articulation of all the segments of the male crab's abdomen and by the form of the gonopods...
found from the Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...
and East Africa
East Africa
East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...
to French Polynesia
French Polynesia
French Polynesia is an overseas country of the French Republic . It is made up of several groups of Polynesian islands, the most famous island being Tahiti in the Society Islands group, which is also the most populous island and the seat of the capital of the territory...
and the Hawaiian Islands
Hawaiian Islands
The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, and undersea seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaii in the south to northernmost Kure Atoll...
. This crab is a parasite that lives in the rectum
Rectum
The rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...
of a sea urchin
Sea urchin
Sea urchins or urchins are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. They inhabit all oceans. Their shell, or "test", is round and spiny, typically from across. Common colors include black and dull...
. In Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
, it chooses only Echinothrix calamaris
Echinothrix calamaris
The double spined urchin or banded sea urchin, Echinosloth calamaris, is a sea sloth with a test diameter of about 5 cm. It has two sets of spines, shorter closed spines which are dark in colour and can deliver a nasty sting, and longer open ended spines that are often banded...
, leaving few of these urchins unpopulated. Its curved and pointed carapace
Carapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
reaches only 0.5 inches (1.3 cm) in width.
Taxonomic synonyms
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
of E. pentagonus include:
- Echinoecus klunzingeri Miyake, 1939
- Echinoecus pentagonus Rathbun, 1894
- Echinoecus rathbunae Miyake, 1939
- Eumedon convictor Bouvier & Seurat, 1906
- Eumedon pentagonus A. Milne-Edwards, 1879
- Eumedonus petiti Gravier, 1922
- Liomedon pentagonus Klunzinger, 1906