Tunicates are Bag Body animals

Tunicates live in a tough bag or 'Tunic" made of cellulose and protein. They are very strange creatures! When born they have a structure not unlike a nerve chord so they are actually Chordates. However, when they become adults, the lose this feature and settle down to a life of sunbaking and filtering the sea water for planktonic food. Tunicates also have gill slits and use them to filter sea water as well as to breathe. Gills as you know are found in fish and amphibians. They reproduce from an egg and a sperm and form a tadpole shaped larvae complete with the little nerve chord and Gill Slits. The settle on the sea floor within hours of being born and metamorphosize into their adult shape, the Bag. Next , many species form colonies by asexual cloning. Colonies are made up of genetically identical copies of the original adult. They are often very ornate, distant relatives to the vertebrates..

 

 
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The complex and beautiful Magnificent Ascidian, Botrylloides magnicoem is a very extraordinary colony of clones. I explain how it is constructed in my Marine Biology course.

The Colonial Flask Ascidian, Clavelina clearly shows its gill slite and the inhalant and exhalant siphon.

On the right is the Carpet Ascidian known as Botrylloides. It resembles sponges but it has regular patterns of animals around common exhalent chimneys.

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The Compound Ascidean is called Polycitor. Long orange animals live in a tough tunic made of a very solid jelly. The jelly contains toxic sterols which have benefits in treatment of some cancers.There are white ones as well, shown here. Sycozoa is commonly called the Brain Ascidean. Tunicates are lined up in rows on the very tough communal structure in which they live.