Holasteroida

Holasteroida

[‚häl·ə·stə′rȯid·ə]
(invertebrate zoology)
An order of exocyclic Euechinoidea in which the apical system is elongated along the anteroposterior axis and teeth occur only in juvenile stages.
References in periodicals archive ?
The two families of Holasteroida known from antarctic waters, the Urechinidae and the Pourtalesiidae, are essentially deep-sea forms with a wide distribution in the ocean basins.
Of these, eight involve brood-protection (Cidaroida, Temnopleuroida, Echinoida, Spatangoida [including Schizasteridae and Brissidae], Holasteroida, Cassiduloida, Clypeasteroida).