What are seasquirts?

An oyster reef

Seasquirts also known as Ascidians or Tunicates and can be found growing on an oyster reef. They are small animals that attach themselves to an oyster shell and remain there throughout their life. They are a very diverse group of invertebrates, whose life style is similar to sponges but their structure is more complex.

Seasquirts spend their time filtering small particles from the bay water. They all feed by sucking water in through one opening and blowing it out through another. Seasquirts can squirt a stream of water as far as two feet away.

Many are individual animals, but living in a group, others form attached colonies. These colonies have special structures, like stems that support the whole colony.

What do they look like?


Many species are translucent or whitish in colour but some species are much more colourful and can be red, brown, yellow and even blue.

The coastal habitats of solitary species, and the fact that their tunics are the most solid of all the Urochordates often means that they can be found intact along the seashore after storms and rough seas.

They can still contain water and if trodden on or squeezed this water will shoot out of the exhalent siphon. It is this that gives them their common name of seasquirts. The name Tunicates arises from the existence of the tunic.