Link to Rocky Shore Animals
Although sea squirts look like primitive animals they are really quite advanced, with a well developed digestive system and a tadpole larva which has the beginnings of a spinal cord, which is of course present in all vertebrates. Solitary sea squirts are attached to rocks and suck water in through one of their two syphons. Any food items are strained out and the filtered water is expelled through the other syphon.
Some seasquirts live in colonies which spread in thin layers over rock or seaweed stalks. The individuals are arranged around a common opening which gives them a beautiful pattered appearance.
Colonial Seasquirt (Photo: Paul Tyler)
These flower-like patterns are colonial seasquirts. Each 'petal' is an individual animal arranged around a central exhaust syphon. Sea squirts are so named because when squeezed, for instance when hauling up a mooring rope, water jets energetically from the syphons as the the body is compressed. (See Rocky seabed section for more sea squirts)
by Paul TylerNext Section