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Sponge, Tunicates & Bryozoa

The animals in this group form large colonies which can cover huge areas of rock or other hard surface - even if this hard surface is the shall of another animal! Each group described on this page have significant differences, and are not related at all despite their aesthetic similarities.


Star Ascidian © Katherine Dunsford


Tunicates are animals which have a tough leathery outer coating, and two 'holes', or siphons, which they use to take in water and therefore food into thier bodies. Tunicate species can live on their own attached to hard surfaces under the water, such as sea squirts, or can form large colonies such as Star Ascidian. 


Sponges are very simplistic animals, and they get their food by filtering small particles of detritus and other food particles from seawater.


Bryozoans may often be overlooked or mistaken for decaying patches on seaweed. However they are colonial animals which live on some seaweeds, rocks and other hard surfaces. They have tentacles which they use to catch their food, and themselves are a tasty snack for sea slugs.  


Images by Lawson Wood Ocean Eye Films & Katherine Dunsford

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