MCS logo, two figures in silhouette - a dolphin jumping, superimposed by a diving human, with the slogan 'Seas fit for life'.

MCS: Lancashire area group

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Right: Photograph of the tunicate (sea squirt) Corella parallelogramma (Müller) by Christine Ryan, note the almost transparent outer skin or tunic, through which relatively complex internal structures are clearly visible.

Tunicates or sea squirts possess a tadpole-like larval stage, and while most signs of a spinal chord have been lost in the adult animal, their internal organisation is far more complex than the sponges they may resemble superficially.

The are unusual in having an outer skin ('test' or 'tunic') composed of carbohydrates - structural polymers more usually associated with plants. The tunic may shelter a single animal (as here), or a colony composed of clones budded from a parent individual.

  Photo of a dogfish warily watching the camera.

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