Cladus: Eukaryota
Supergroup: Unikonta
Cladus: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Echinodermata
Subphylum: Eleutherozoa
Superclassis: Cryptosyringida
Classis: Echinoidea
Subclassis: Euechinoidea
Superordo: Gnathostomata
Ordo: Holectypoida
Subordines: Conoclypina - Echinoneine - Holectypina - Pygasterina
Name
Holectypoida Duncan, 1899
References
* Natural History Museum [1]
The Holectypoida are an order of sea urchins related to the sand dollars. The order consists of just two living genera, but was once more diverse.
In appearance, the living holectypoids are similar to sand dollars, but with less flattened bodies and an oval outline. They also lack the petal-like patterns found on the bodies of sand dollars.
References
Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 981. ISBN 0-03-056747-5.
Retrieved from "http://en.wikipedia.org/"
All text is available under the terms of the GNU Free Documentation License
