Didemnum perlucidum

White colonial sea squirt

Didemnum perlucidum

Common name:

White colonial sea squirt

Scientific name:

Didemnum perlucidum

Alternative common names:

White crust tunicate


Description:

Didemnum perlucidum is a widely distributed colonial tunicate that is believed to be native to tropical Indo-Pacific waters. Colonial tunicates are communities of individuals, called zooids, which share a protective layer called a tunic. Although considered cryptogenic, D. perlucidum was first described in the Caribbean and later found in West Africa, Indo-Pacific (including Panama Canal, Guam and Hawaii), Brazil and the Gulf of Mexico, where it has colonized harbors, rock, wood, rope and other man-made structures. The colonies have a marble appearance, showing varying colors, including white and gray, yellow, or brown – with the darker color due to fecal pellets. The largest D. perlucidum colonies measure 8 cm but are only 1-3 mm thick.

White crust tunicate

Additional Information


Where does this species come from?

Didemnum perlucidum is cryptogenic but believed to be native to tropical Indo-Pacific waters. It was first described in the Caribbean and later found in West Africa, Indo-Pacific (including Panama Canal, Guam and Hawaii), Brazil and the Gulf of Mexico, where it has colonized harbors, rock, wood, rope and other man-made structures.

What is its invasive status in South Africa?

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

Where in South Africa is it a problem?

Didemnum perlucidum has not been recorded in South African waters.

How does it spread?

Didemnum perlucidum is likely introduced through ship fouling.

Why is it a problem?

Didemnum perlucidum grows on boat hulls and on cultured mussels, such as Perna perna in Brazil. It overgrows mussels and could damage the bivalve industry.

What does it look like?

Description: Colonies are marbled in appearance – white and gray, yellow, or brown – with the darker color due to fecal pellets visible in the cloacal canals, where the tunic has only sparse spicule. The largest colonies measure 8 cm but are only 1-3 mm thick.

Habitat: Colonies of D. perlucidum usually occur in harbors or man-made structures, but has also been found encrusting rock, wood, ropes, or other structures.

Breeding: Colonial tunicates reproduce both asexually by budding and sexually from fertilized eggs that develop into larvae.