Thaliacea

tunicate class

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July 14, 2026

Quick Summary

The Thaliacea are a class of tunicates, which are small marine animals belonging to the subphylum Tunicata. Unlike the more common benthic (bottom-dwelling) tunicates like sea squirts, Thaliacea are pelagic, meaning they float and swim in open water.12

This class includes free-swimming forms such as salps and dolioloids. Their structure suggests they are adapted ascidians that have evolved for life in the open sea. Thaliaceans often exhibit specialized reproduction, involving a complex alternation between sexual and asexual phases. They are found globally in marine environments and play a role in the ocean's food chain.12

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tunicate
Annotated classification
Class ThaliaceaPelagic forms; atrial aperture directed toward the rear of each zooid; asexual buds form from a ventral stolon; about 70 species.Order PyrosomidaZooids embedded in a tube open at one end.Order DoliolidaComplex alternation of generations between a
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Class ThaliaceaPelagic forms; atrial aperture directed toward the rear of each zooid; asexual buds form from a ventral stolon; about 70 species.Order PyrosomidaZooids embedded in a tube open at one end.Order DoliolidaComplex alternation of generations between a
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tunicate
Size range and diversity of structure
Thaliacea. Ascidians are largely benthic animals. They often form colonies, comprising a few to many individuals (zooids), which reach up to two metres in length. Solitary (noncolonial) forms range from one millimetre to over 20 centimetres in length. The adult appendicularian resembles the tadpole larva…
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Thaliacea. Ascidians are largely benthic animals. They often form colonies, comprising a few to many individuals (zooids), which reach up to two metres in length. Solitary (noncolonial) forms range from one millimetre to over 20 centimetres in length. The adult appendicularian resembles the tadpole larva…
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