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Dendrochirotida

provided by wikipedia EN

Dendrochirotida are an order of sea cucumbers. Members of this order have branched tentacles and are suspension feeders. Examples include Thyonella and Cucumaria.

Characteristics

Holothurians in this order are characterised by ten to thirty much branched tentacles which are sometimes digitate. They also have ring structures composed of ten calcareous plates circling the pharynx. They have both retractor and introvert muscles which means they can retract the tentacles into the mouth when not feeding.[1] The body wall is either firm with large ossicles or of a soft consistency with few ossicles. In some genera the animals attach themselves to hard surfaces but in others they burrow into soft sediments. Prey is captured by the sticky tentacles and transferred to the mouth. The larvae are lecithotrophic, not feeding on plankton but surviving only on materials already present in the eggs until they settle and become juveniles.[2]

Taxonomy

Order: Dendrochirotida

References

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Dendrochirotida: Brief Summary

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Dendrochirotida are an order of sea cucumbers. Members of this order have branched tentacles and are suspension feeders. Examples include Thyonella and Cucumaria.

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Classification

provided by World Register of Marine Species
No order of Holothuroidea is as diverse and problematic as the Dendrochirotida. The rank and circumscription of several clades in the Dendrochirotida have changed in recent publications, especially in Smirnov 2012, Thandar 2017, and Martins 2017. These changes have been followed to various degrees by recent taxonomic studies. Smirnov and Thandar diagnosed clades but did not evaluate them phylogenetically, while Martins pursued a morphological phylogenetic analysis. Miller et al's 2017 broad molecular phylogenetic study of holothuroids also included several dendrochirotids. Results from these studies are in conflict and indicate that our understanding of family level classification in dendrochirotids is inadequate. Several of the papers themselves note that several families are likely polyphyletic, while Michonneau & Paulay 2014 documented intraspecific variability in characters used to defined family-level taxa. Rather than follow this rapidly changing classification landscape, the WoRMS dendrochirotid classification will for now hold genera in their pre-2012 position, pending rigorous analyses. Names recently recognized at the family level are included in the database, but without assignment of species.
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Paulay, Gustav [email]