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Sea daisies (infraclass Concentricycloidea; order Peripodida) make up an unusual group of deep-sea taxa belonging to the phylum Echinodermata, with three species described in the genus Xyloplax. Intestine and anus are absent.
The Asterozoa are a subphylum in the phylum Echinodermata, within the Eleutherozoa.Characteristics include a star-shaped body and radially divergent axes of symmetry. The subphylum includes the classes Asteroidea (the starfish or sea stars), Ophiuroidea (the brittle stars and basket stars), Somasteroidea (early asterozoans from which the other classes most likely evolved), and Stenuroidea ...
Five extant classes of echinoderms are generally recognized: the Asteroidea (starfish, with over 1900 species), Ophiuroidea (brittle stars, with around 2,300 species), Echinoidea (sea urchins and sand dollars, with some 900 species), Holothuroidea (sea cucumbers, with about 1,430 species), and Crinoidea (feather stars and sea lilies, with ...
The class Asteroidea belongs to the phylum Echinodermata. As well as the starfish, the echinoderms include sea urchins, sand dollars, brittle and basket stars, sea cucumbers and crinoids. The larvae of echinoderms have bilateral symmetry, but during metamorphosis this is replaced with radial symmetry, typically pentameric. [12]
Eleutherozoa is a subphylum of echinoderms. They are mobile animals with the mouth directed towards the substrate. They usually have a madreporite, tube feet, and moveable spines of some sort. It includes all living echinoderms except for crinoids. The monophyly of Eleutherozoa has been proven sufficiently well to be considered "uncontroversial ...
A brittle star, Ophionereis reticulata A sea cucumber from Malaysia Starfish exhibit a wide range of colours. This List of echinoderm orders concerns the various classes and orders into which taxonomists categorize the roughly 7000 extant species [1] as well as the extinct species of the exclusively marine phylum Echinodermata.
Xyloplax medusiformis was the first sea daisy to be described. It was clearly an echinoderm but at first it was considered to be sufficiently different from starfish, class Asteroidea, as to warrant it being placed in a new class of its own, the Concentricycloidea.
Pedicellaria of Acanthaster planci Generalized pedicellaria of an (a) asteroid and (b) echinoid. A pedicellaria (pl.: pedicellariae) is a small wrench- or claw-shaped appendage with movable jaws, called valves, commonly found on echinoderms (phylum Echinodermata), particularly in sea stars (class Asteroidea) and sea urchins (class Echinoidea).