''Clypeaster japonicus'', the Japanese sea biscuit, is a species of

sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...

in the

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

Clypeasteridae Clypeasteridae is a family of sea urchins in the order Clypeasteroida. This family was first scientifically described in 1835 by the Swiss-American biologist Louis Agassiz. Genera The World Register of Marine Species list the following genera a ...

. This species was first

scientifically described A species description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species that have be ...

in 1885 by the German zoologist

Ludwig Heinrich Philipp Döderlein Ludwig Heinrich Philipp Döderlein (3 March 1855, Bad Bergzabern – 23 April 1936, Munich) was a German zoologist. He specialized in echinoderms, particularly sea stars, sea urchins, and crinoids. He was one of the first European zoologists to ...

Description

This is a large species with a strong

test Test(s), testing, or TEST may refer to: * Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities Arts and entertainment * ''Test'' (2013 film), an American film * ''Test'' (2014 film), ...

, growing to a maximum length of around . In shape it is an elongated pentagon, the aboral (upper) surface slightly higher at the apex than at the margins. The length of the petaloid area amounts to two thirds or more of the total length of the test. The anterior petal is open

distally Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

while the two posterior, paired petals are closed distally. The oral (under) surface is fairly flat, but deeply concave around the mouth, with conspicuous, but short, indented food grooves. The

anus The anus (Latin, 'ring' or 'circle') is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, the residual semi-solid waste that remains after food digestion, which, d ...

is on the oral surface near the posterior margin. The primary spines are rather longer than the densely felted secondary spines. When alive, this species is a uniform brown colour apart from the petals, which are a darker brown. The bare test is grey or pale brown.

Distribution

This sea biscuit is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to Japanese waters. Its range extends from northern

Honshu , historically called , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island separ ...

southwards to southern

Kyushu is the third-largest island of Japan's five main islands and the most southerly of the four largest islands ( i.e. excluding Okinawa). In the past, it has been known as , and . The historical regional name referred to Kyushu and its surroun ...

. Its depth range is from .

References

{{Taxonbar, from=Q2505086 Animals described in 1885 Clypeaster