Clypeaster japonicus
species of echinoderm
Clypeaster japonicus, the Japanese sea biscuit, is a species of sea urchin in the family Clypeasteridae. This species was first scientifically described in 1885 by the German zoologist Ludwig Heinrich Philipp Döderlein.
Description
This is a large species with a strong test, growing to a maximum length of around 120 mm (5 in). 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 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 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.
Begin with the source’s own compact description: “Clypeaster japonicus” is species of echinoderm. The dossier treats that line as a proposition to test through Clypeaster, japonicus and species, not as a finished interpretation.
Why this record matters
The phrase “species of echinoderm” supplies a clear boundary for inquiry. It also exposes the unanswered questions: who defined that boundary, when it became stable and which sources sit outside it.
Datasets, specimens, observations and peer-reviewed methods provide the appropriate test for the technical claims summarized here. The source revision retrieved here is dated May 21, 2026. The linked authority identifier is Q2505086. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1885.
Scientific names, classifications and consensus can change while older terminology persists in catalogues and historical literature. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Check terminology, classification and the date of the cited evidence. Scientific names and technical consensus can change while older records retain historical value.
- Current terminology
- Classification context
- Finding cited technical literature
Primary datasets, specimen catalogues, standards bodies and the most recent peer-reviewed literature.
Three-step research path
- Establish the record: confirm the title “Clypeaster japonicus”, its source revision and the description used here.
- Expand the search: follow Clypeaster japonicus primary sources, Clypeaster japonicus archive and Clypeaster research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Clypeaster japonicus”?
- Has classification or technical consensus changed since the cited source?
- Is the terminology current, historical or disputed?
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This entry incorporates text from “Clypeaster japonicus” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.