Category: Echinozoa

Belongs within: Euechinoidea.Contains: Hemicidaroida, Calycina, Phymosomatoida, Echinoida, Temnopleuroida. The Echinacea are a clade of regular echinoids in which the teeth of the lantern have developed a keel on the inner surface (stirodont type, modified to camarodont type with a closed foramen magnum in some subgroups). Within the Echinacea, members of the family Arbaciidae possess characteristic… Continue reading Echinacea

Belongs within: Echinozoa.Contains: Cidarinae, Histocidarinae, Rhabdocidarinae, Goniocidarinae, Ctenocidarinae, Archaeocidaris. The Cidaroida are a group of echinoids with relatively narrow ambulacra and without gill slits. They include the only living echinoids ancestrally without external gills and, with a fossil record going back to the Upper Silurian, they pre-date most other living echinoid groups. Cidaroids commonly have modified… Continue reading Cidaroida

Belongs within: Holothuroidea. The Elasipodida are a group of mostly deep-sea holothuroids with a bilaterally symmetrical body pattern in which the dorsal tube feet have become modified into elongate sensory processes (Pawson 1966). Respiratory trees are absent. Members of this group include some of the most atypical species of sea cucumber, such as the ‘sea… Continue reading Elasipodida

Belongs within: Echinozoa.Contains: Elasipodida, Aspidochirotida, Dendrochirotacea, Apodida. The Holothuroidea include the sea cucumbers, echinoderms in which the characteristic pentaradial symmetry of the phylum has been superimposed by a secondary bilaterality. Holothuroids have also reduced the skeletal plates to become much more flexible than other echinoderms. In members of the Apodacea, the tube feet have also… Continue reading Holothuroidea

Belongs within: Dendrochirotacea.Contains: Calclamnidae. The Cucumariidae are a group of sea cucumbers characterised by the presence of ten branching tentacles. Sclerites of possible cucumariids are known as far back as the middle Ordovician where they are represented by the Staurocaudininae, oval sclerites with a distinct marginal zone and perforated central zone. The Devonian Devonothyoninae possessed… Continue reading Cucumariidae

Belongs within: Holothuroidea.Contains: Stichopus, Priscopedatus, Holothuria. The Aspidochirotida are a group of sea cucumbers with a bilaterally symmetrical body plan in which the dorsal tube feet are modified into papillae or warts. Members of this group include the living families Synallactidae, Holothuriidae and Stichopodidae, and most members of the fossil form-family Stichopitidae (Pawson 1966). Stichopitidae are… Continue reading Aspidochirotida

Belongs within: Holothuroidea.Contains: Achistrum, Theelia, Stueria. The Apodida are a group of cylindrical holothuroids characterised by the absence of respiratory trees, anal papillae and generally tube feet. Among living families, the Synaptidae are vermiform and have a scleritome comprised of perforated plates and anchors. The Myriotrochidae and Chiridotidae possess wheel sclerites which are more complex… Continue reading Apodida

Belongs within: Echinacea. The Temnopleuroida are a group of echinoids with a camarodont lantern known from the Lower Jurassic to the present (Fell & Pawson 1966). They are commonly associated with quieter, deeper offshore waters and may tolerate soft bottoms. Characters (Fell & Pawson 1966): Lantern camarodont (unknown in Glyphocyphidae). Test usually sculptured with ridges… Continue reading Temnopleuroida

Belongs within: Echinodermata.Contains: Ophiocistioidea, Holothuroidea, Palaechinoida, Echinocystitoida, Cidaroida, Euechinoidea. The Echinozoa are a clade of free-living echinoderms with tests lacking arms or radiating appendages. Modern representatives are divided between the Echinoidea, sea urchins, and Holothuroidea, sea cucumbers. The Echinoidea have an ancestrally subspherical test bearing mobile appendages (including spines). The ancestral echinoid morphology includes a… Continue reading Echinozoa