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Articulata are a subclass or superorder within the class Crinoidea, including all living crinoid species. They are commonly known as sea lilies (stalked crinoids) or feather stars (unstalked crinoids). The Articulata are differentiated from the extinct subclasses by their lack of an anal plate in the adult stage and the presence of an ...
A stalked crinoid (white) and a comatulid (red) in deep sea, showing the differences between these two sister groups. Most modern crinoids, i.e., the feather stars, are free-moving and lack a stem as adults. Examples of fossil crinoids that have been interpreted as free-swimming include Marsupites, Saccocoma and Uintacrinus. [23]
Pentacrinoidea includes most major crinoid groups, such as the living Articulata and extinct Flexibilia (together forming the parvclass Cladida) as well as the extinct Disparida. It is a stem-based taxon , defined as including all crinoids closer to Pentacrinites (a Jurassic articulate) or Apektocrinus (an Early Ordovician cladid ) than to ...
This list of crinoid genera is an attempt to create a comprehensive listing of all genera that have ever been considered to be crinoids, excluding purely vernacular terms.
Sea lilies are crinoids with a calyx and five pairs of feather-like arms standing on a long stalk which is retained throughout the animal's life. This stalk is attached to the substrate by means of an enlarged, terminal disc or alternatively by means of several branching, irregular radicular cirri arising from the lowest part of the stem. [ 3 ]
Pentacrinites is an extinct genus of crinoids that lived from the Hettangian to the Bathonian of Asia, Europe, North America, and New Zealand.Their stems are pentagonal to star-shaped in cross-section and are the most commonly preserved parts. [1]
Like all crinoids, it is a filter feeder, spreading its arms and pinnules widely to catch plankton and small particles of detritus from the water flowing past. The sexes are separate, and females brood their young in their brood pouches; the larvae may reach 1.8 mm (0.07 in) in length before being expelled from the pouch and falling to the sea ...
Promachocrinus is a genus of free-swimming, stemless crinoids.It was a monotypic genus, with the only species in the genus being Promachocrinus kerguelensis, until the discovery of four new species, establishment of two others previously described and the transfer of another species to the genus in 2023. [2]