Asterostomatidae

Belongs within: Irregularia. The Asterostomatidae are a possibly polyphyletic group of heart urchins characterised by the loss of petals and/or fascioles (Fischer 1966). Moving to the top when shifting to the depths Published 25 November 2023 In 1966, the Treatise on Invertebrate Paleontology volumes dealing with the stem-less echinoderms (sea urchins, sea stars, etc.) reached… Continue reading Asterostomatidae

Asteriidae

Belongs within: Forcipulatida.Contains: Leptasterias, Asterias. The Asteriidae are a family of starfish with a swollen body and both straight and crossed pedicellariae. Of the three subfamilies listed below, the Pycnopodiinae have the aboral skeleton obsolescent whereas Neomorphaster has the primary aboral plates conspicuously enlarged. Pycnopodiinae have inferomarginals with two spines, heavily wreathed with pedicellariae, and… Continue reading Asteriidae

Published
Categorised as Asterozoa

Echinoida

  Purple sea urchin Strongylocentrotus purpuratus, copyright Kirt L. Onthank.   Belongs within: Echinacea.Contains: Strongylocentrotus, Echinus. The Echinoida are a group of echinoids with a camarodont lantern known from the Palaeocene (possibly the Upper Cretaceous) to the present. Gill slits are shallow in most families but are narrow, distinct and commonly deep in Toxopneustidae (Fell… Continue reading Echinoida

Published
Categorised as Echinozoa

Asterias

Belongs within: Asteriidae. Asterias is a cosmopolitan genus of sea stars with a large disc and relatively broad arms. Characters (from Spencer & Wright 1966): Disc fairly large, arms 5 or 6, rather broad and short; aboral skeleton an open network with spines in nearly regular series along midline and margin of arms but elsewhere… Continue reading Asterias

Published
Categorised as Asterozoa

Echinus

Belongs within: Echinoida. Echinus is a genus of sea urchins known from the Pliocene to the present (Fell & Pawson 1966). Characters (from Fell & Pawson 1966): Test widest at circular ambitus; ambulacral plates trigeminate, with primary tubercle on every alternate (or every third) ambulacral plate. Buccal membrane containing scattered plates. Secondary radioles only slightly… Continue reading Echinus

Published
Categorised as Echinozoa

Holothuria

Belongs within: Aspidochirotida. Holothuria is a genus of sea cucumbers found primarily in coastal regions, particularly around coral reefs. Some species such as the edible sea cucumber H. edulis are eaten by humans. Characters (from Rowe 1969): Tentacles 17–30, usually 20, pedicels and papillae variously arranged on the ventral and dorsal sides respectively; anal papillae… Continue reading Holothuria

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Categorised as Echinozoa

Ophiacanthidae

Belongs within: Ophiurida.Contains: Ophiacantha. The Ophiacanthidae are a group of brittle stars with slender arms bearing numerous long, often glassy spines (Spencer & Wright 1966). Rise to the surface, retreat to the depths Published 7 December 2022 Despite being the most speciose of the recognized modern classes of echinoderms, the brittle stars (Ophiuroidea) are perhaps… Continue reading Ophiacanthidae

Orthopsidae

Belongs within: Euechinoidea. The Orthopsidae are a group of echinoids of uncertain affinities known from the Lower Jurassic to the Upper Cretaceous (Fell & Pawson 1966). Characters (from Fell & Pawson 1966): Test small or large, regularly hemispherical or globular. Lantern camarodont (known only in Orthopsis). Ambulacra simple, without compounded plates, at most with only… Continue reading Orthopsidae

Published
Categorised as Echinozoa

Calycina

Belongs within: Echinacea. The Calycina are a group of echinoids known from the Lower Jurassic (possibly the Upper Triassic) to the present. Members of this group commonly have one or more large suranal plates over the apical system that superficially resemble a calyx. They are first represented in the fossil record by the Acrosaleniidae, which… Continue reading Calycina

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Categorised as Echinozoa

Hemicidaroida

Belongs within: Echinacea. The Hemicidaroida are a group of echinoids with a stirodont lantern and perforate primary tubercles known from the Upper Triassic to the Upper Cretaceous (Fell & Pawson 1966). <==Hemicidaroida [Hemicidarina] | i. s.: Allomma Pomel 1883FP66 | `–*A. normanniae (Cotteau 1863) [=Pseudodiadema normanniae]FP66 | Colpotiara Pomel 1883FP66 | `–*C. matheyi (de Loriol… Continue reading Hemicidaroida

Published
Categorised as Echinozoa