Didemnum vexillum

Carpet sea squirt

Didemnum vexillum

Common name:

Carpet sea squirt

Scientific name:

Didemnum vexillum

Alternative common names:


Description:

Didemnum vexillum is an aggressive and rapidly spreading colonial tunicate that forms yellowish-cream extensive thin sheets, which overgrow and encrust rocks, wood, ropes, shells and/or other structures, as well as other organisms such as hydroids, sponges and oysters. It also encrusts itself as it forms large sponge-like-masses that have flexible leaf or flag like projections. As such, the colonies may appear to be folding in on themselves and neighboring surfaces. Didemnum vexillum is believed to have originated from the Northwest Pacific, probably Japan, but has been also reported in other parts of the world such as Europe, North America and New Zealand.

Additional Information


Where does this species come from?

Northwest Pacific, probably Japan, but has also been reported in other parts of the world such as Europe, North America and New Zealand.

What is its invasive status in South Africa?

NEMBA 2020 2020 Category XX: Didemnum vexillum has not been recorded in South African waters.

Where in South Africa is it a problem?

Didemnum vexillum has not been recorded in South African waters.

How does it spread?

Didemnum vexillum is likely introduced through ship fouling.

Why is it a problem?

Didemnum vexillum is a concern in fisheries and aquaculture as causes significant economic damages in these sectors. Ecologically, its colonies have resulted in negative impacts on other species where in some areas its rapid expansion has reduced the abundance of previously established benthic species.

What does it look like?

Description: Didemnum vexillum forms yellowish-cream extensive thin sheets that form large sponge-like masses which often have long, flexible leaf or flag like projections. Sometimes the colonies appear to be folding in on themselves.

Habitat: Didemnum vexillum colonies occur in harbors or man-made structures, but has also been found encrusting rock, wood, ropes, or other structures.

Breeding: Didemnum vexillum colonies are capable of rapid growth and expansion through both sexual and asexual reproduction, and as such are able to quickly colonize large areas of artificial and natural substrata.