Sea squirts, sea tulips and other ascidians

Sea squirts and sea tulips are collectively known as ascidians (Ancient Greek: askidion = wineskin), characterised by a tough outer “tunic” made of cellulose.

Ascidians are the evolutionary link between invertebrates and vertebrates. They are an invertebrate with some primitive vertebrate features, such as a primitive backbone during a stage in their life cycle.

Adult ascidians are “sessile” (unable to move around): they attach themselves to rocks or shells. Adult ascidians filter food particles from the water by pumping water in one siphon and out the other. This filter feeding habit allows adult ascidians to accumulate pollutants, so by observing ascidian populations, we can get a good indication of pollution levels of the environment.

Sydney has over 80 species of ascidians. They are usually found in shallow water environments. Their common name of sea squirt arises from their habit of squirting a jet of water when you stand on or near them when they are uncovered at low tide. And sea tulips are named for their flower-like appearance and stalked bodies.

Learn where the name "Cunjevoi" comes from and what this sea squirt is being used for in today's society. Discover the unique relationship between the sea tulip and a sponge and learn why they grow together.

Marvel at the Dark Ascidians' range of colours, sizes and shapes that even scientists in the past assumed they were all different species.

Sea squirts & sea tulips factsheets

6 Fact Sheets in this section