Species Information

Sea squirt (Didemnum vexillum) Sea squirt (Didemnum vexillum)
A. Pappal
Sea squirt (Didemnum vexillum)
A. Pappal
Sea squirt
Didemnum vexillum

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Characteristics
  • Cream, white, tan, or yellow
  • Dense colonies of microscopic, individual animals (zooids)
  • Colonies grow up to 12-18 in (30-46 cm) long
  • In slow-moving waters, may form long, ropey, or beard-like colonies that commonly hang from hard substrates such as docks, lines, and ship hulls
  • In faster-moving waters, may form low, undulating mats that encrust and drape rocky seabeds (pebbles, cobbles, boulders, and rock outcrops)

Habitat
  • Hard surfaces such as docks, pilings, moorings, ship hulls, rocks, and seafloor
  • Primarily below the low-tide line to continental shelf depths of 210 ft (65m)

Known Distribution in the Northeast
  • Northeastern U.S. (New Jersey, New York, Connecticut, Rhode Island, Massachusetts, New Hampshire, Maine)
  • Covers much of Georges Bank and Gulf of Maine

Impacts
  • Alters marine habitats and threatens to interfere with fishing, aquaculture, and other coastal and offshore activities
  • Grows over organisms such as tunicates, sponges, seaweeds, hydroids, anemones, bryozoans, scallops, mussels, and oysters
  • Covers siphons of shellfish living in the seabed
  • Blocks bottom-feeding fish from reaching their prey

Sea squirt (Didemnum vexillum)
L. Stefaniak, UConn
Sea squirt (Didemnum vexillum)
L. Stefaniak, UConn
Sea squirt (Didemnum vexillum)
Bostwick
Sea squirt (Didemnum vexillum)
Becca Toppin (UNH)
Sea squirt (Didemnum vexillum)
A. Pappal
Sea squirt (Didemnum vexillum) covering rocks, mussels, and barnacles in Harpswell, Maine
Bostwick
Sea squirt (Didemnum vexillum)
A. Pappal