Molgula manhattensis

Sea Grapes

Molgula manhattensis

Common name:

Sea Grapes

Scientific name:

Molgula manhattensis

Alternative common names:


Description:

Molgula manhattensis is a greenish-olive or yellowish-green grape-like rounded solitary tunicate, sometimes laterally flattened, with a globular body shape. The tunic is firm, tough and moderately thick. Some areas on the tunic may develop into small hair-like projections called papillae which frequently catch and accumulate particles or organisms to its tunic and siphons. The two siphons are fairly close together at the anterior end. Large specimens of M. manhattensis can measure 20 -50 mm in length and height.

Additional Information


Where does this species come from?

Molgula manhattensis is native to the East and Gulf Coasts of the United States and has been introduced to the West Coast of North America, Europe, Australia, Argentina and Japan.

What is its invasive status in South Africa?

NEMBA 2020 2020 Category XX: Molgula manhattensis has not been recorded in South African waters.

Where in South Africa is it a problem?

Molgula manhattensis has not been recorded in South African waters.

How does it spread?

Ship hull fouling

Why is it a problem?

Molgula manhattensis negatively affects oyster aquaculture because it fouls oyster stock and oyster cultch (empty shells, used for spat settlement).

What does it look like?

Description: Greenish-olive or yellowish-green grape-like solitary ascidian, sometimes laterally flattened, with a globular body shape. It has two siphons that are fairly close together at the anterior end.

Habitat: Molgula manhattensis attaches to firm substrates, such as rocks, boulder, shell, and cobble, as well as man-made structures. It can be found on sands as well. Tolerates pollution.

Breeding: Solitary ascidians release both, eggs and sperm to the atrial chamber. Eggs may be self-fertilized or fertilized by sperm from nearby animals, but many species have a partial block to self-fertilization.