The subphylum Urochordata, is also sometimes known as the Tunicata. These animals are commonly known as tunicates or sea squirts. Some pelagic tunicates are known as salps. There are two classes recognized within the subphylum: Thaliacea and Ascidiacea. The body of an adult tunicate is quite simple. Essentially it is a sack with two siphons through which water enters and exits. Many tunicates have a larva that is free-swimming and exhibits all chordate characteristics, including a notochord. In many tunicates this "tadpole larva" eventually attaches to a hard surface and loses its tail, the ability to move, and most of its nervous system. The tunicate group knows as salps are entirely free-swimming, however.
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Photograph and article from Wikipedia on the tunicates, including their life history, fertilisation and ecology.
Home page for Ascidian News, a twice yearly newsletter published by Charles and Gretchen Lambert, with recent worldwide publication citations, meetings abstracts and work in progress. The Ascidiaceae are a family in the Phylum Urochordata and are commonly known as tunicates or sea squirts.
Photographs and information on this species, including its taxonomy, description, habitat, distribution, life history, population biology, physical tolerances, community ecology and information on its invasivness.
Hundreds of images of ascidian species photographed all over the world, and a few photographs of salps (Thaliacea).
Photographic study by Jean-Marie Cavanihac of these marine organisms.
Species list from the USGS on the nonindigenous tunicates found in US waters, with factsheets and collection details for each.
Article with photographs by Wim van Egmond on this Larvacean and its delicate “house”.
Photograph and article from Wikipedia on this barrel-shaped tunicate, including its distribution, nervous systems, relationships and classification.
Article by Wim van Egmond on the life cycle and development of these Ascidians with several photographs.
Photographs and information on this species, including its taxonomy, description, habitat, distribution, life history, population biology, physical tolerances, community ecology and invasion information.
Information from the Earthlife Web on the colony-forming Pyrosomida and the non-colonial Salpida and Doliolida, including their description and their complex life cycle.
Article by Richard Howey about tunicates, and the many organisms that made their home on the outer surface of the specimen he was examining.
Photomicrograph of three developing eggs.
Photomicrograph of two tadpole-like larvae developing inside eggs.
Interesting personal account by Jean-Marie Cavanihac of her observations on the eggs and larval stages of the Ascidians and Botryllus, accompanied by excellent photographs. Further accounts of Salps, Doliolids and Larvaceans with more photographs and video clips.
Many photographs of ascidians including both native and introduced species.
Essay by Richard Howey on the tunicates and their biology with a look at other organisms that also foul the hulls of ships.
Introduction to the Urochordata, with photos.
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