Stolidobranchia

tunicate order

Also known as: Ptychobranchiata

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Last updated

July 14, 2026

Quick Summary

The Stolidobranchia are an order within the class Ascidiacea, which are tunicates. Tunicates, also known as subphylum Tunicata or Urochordata, are small marine animals found globally. Adult tunicates are characterized by a tough, secreted tunic containing cellulose. While some are sessile (bottom-dwelling), others are pelagic (free-swimming). A key feature is the tadpole-like larva, which possesses chordate characteristics that are largely lost during metamorphosis into the adult form.1

Within the Ascidiacea, the Stolidobranchia are distinguished by having a gill structure with longitudinal vessels that is folded. This contrasts with other orders like Aplousobranchia (simple, unfolded gills) and Phlebobranchia (gills with longitudinal vessels but without folds).1

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tunicate
Annotated classification
Order StolidobranchiaGill with longitudinal vessels, folded.Class Appendicularia (or Larvacea)Adult small, pelagic, retaining larval notochord and tail; pharynx simple with two gill openings; no distinct atrium; about 70 species.Class Thaliacea
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Order StolidobranchiaGill with longitudinal vessels, folded.Class Appendicularia (or Larvacea)Adult small, pelagic, retaining larval notochord and tail; pharynx simple with two gill openings; no distinct atrium; about 70 species.Class Thaliacea
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