Phlebobranchia

tunicate order

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Last updated

July 2, 2026

Quick Summary

Phlebobranchia is an order within the class Ascidiacea, which are tunicates. Tunicates are small marine animals found worldwide. Adult tunicates are encased in a tough, secreted tunic that contains cellulose. While some tunicates are sessile and bottom-dwelling, others are pelagic, floating in open water.

The Phlebobranchia order is characterized by gills that have longitudinal vessels and bars but lack folds. Their gonads are located on one side, near the digestive tract. This group is part of the larger subphylum Tunicata, which also includes sea squirts, larvaceans, and thaliaceans. Tunicates are important in marine food chains and offer insights into vertebrate ancestry.12

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tunicate
Annotated classification
Order PhlebobranchiaGills with longitudinal vessels and bars, without folds; gonads on one side, near digestive tract.Subclass PleurogonaGonads and digestive tract by side of gill.Order StolidobranchiaGill with longitudinal vessels, folded.
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Order PhlebobranchiaGills with longitudinal vessels and bars, without folds; gonads on one side, near digestive tract.Subclass PleurogonaGonads and digestive tract by side of gill.Order StolidobranchiaGill with longitudinal vessels, folded.
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