#ascidian

Obese ascidian (Phallusia obesa)

He chonky.

A large solitary tunicate, up to 20cm long. Fairly common in southern Australian waters, down to a depth of about 100m. This one was washed up at Port Kennedy, Perth, after the winter storms. 

Like most other tunicates, a filter-feeder with an inhalant and exhalant siphon, related to the vertebrates. They don’t look much like vertebrates as an adult, that’s for sure, but the larvae are tadpole-like and have a notochord. They may be social, or colonial, and many species are pelagic and in open ocean waters. One group, the Larvaceans, have tadpole-like adults that spin an enormous mucus house that they filter seawater through to extract microscopic plankton.

A few species are detritivores, a few are carnivorous, and some shallow-water tropical species have photosyntheic symbiotic algae. The name ‘tunicate’ comes from the rubbery tunic that they use as an exoskeleton. Its comprised of proteins and complex carbohydrates including a form of cellulose.