2025年1月2日 · Crinoid, any marine invertebrate of the class Crinoidea (phylum Echinodermata) usually possessing a somewhat cup-shaped body and five or more flexible and active arms. The arms, edged with feathery projections (pinnules), contain the reproductive organs and carry numerous tube feet with sensory

Crinoids are echinoderms in the phylum Echinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers. [5] They live in both shallow water [ 6 ] and in depths of over 9,000 metres (30,000 ft).

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 ...

2020年5月26日 · Crinoids, like other members of the phylum Echinodermata, are exclusively marine animals with pentaradial symmetry and water-vascular systems. Though some groups have lost the stalk in adult forms, crinoids are considered to follow the stalked, radial morphology, as the stalkless forms are derived from stalked ancestors.

2025年1月3日 · Crinoids are marine invertebrates that belong to the class Crinoidea within the phylum Echinodermata, which also includes starfish, brittle stars, sea cucumbers, and sea urchins. They have a unique, flower-like appearance that constitutes a cup-like crown called theca, the base of which is composed of numerous body ossicles, followed by a stalk.

2017年2月22日 · The Crinoidea (Echinodermata) is one of the five major clades of living echinoderms and has a rich fossil record spanning nearly a half billion years. Using principles of phylogenetic taxonomy and recent phylogenetic analyses, we provide the first phylogeny-based definition for the Clade Crinoidea and its constituent subclades.

2024年10月25日 · Echinoderms first appeared in the Cambrian, with three groups being particularly common as fossils: crinoids, blastoids, and sea urchins. The echinoderm skeleton is composed of numerous small pieces, commonly made of calcium carbonate.

2022年8月24日 · Crinoidea. The Class Crinoidea includes the feather stars and sea lilies. The defining characteristic of this class is that they anchor themselves to a substrate through the use of cirri.

Crinoids are marine animals belonging to the phylum Echinodermata and the class Crinoidea. They are an ancient fossil group that first appeared in the seas of the mid Cambrian, about 300 million years before dinosaurs.

Crinoids are exclusively marine suspension feeding echinoderms that typically have many arms that radiate from a cup-like body (calyx) that may or may not have a thin, columnar stalk. They have an endoskeleton composed of many individual elements (ossicles) composed of calcium carbonate and connected by ligamentary tissue.