Species Information

Sheath tunicate on rockweed Sheath tunicate on rockweed
A. Pappal
Sheath tunicate on rockweed
A. Pappal
Sheath tunicate
Botrylloides violaceus

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  • Usually orange, sometimes red or dull purple
  • Individual animals (zooids) arranged in loose circles, rows, or dense colonies
  • Dense colonies can be extensive, creating firm, gelatinous coating on submerged structures; colony sometimes forms lobes

  • Grows on rocks, shells, pilings, seaweeds, ship hulls, and other submerged surfaces
  • Usually below low-tide line

Known Distribution in the Northeast
  • Newfoundland to Florida
  • Native to northwestern Pacific Ocean

  • Competition with native species (invertebrates and algae)  for living space
  • Grows over other organisms, interfering with their feeding and other behaviors

Sheath tunicate (Botrylloides violaceus)
Dann Blackwood (USGS)
Sheath tunicate with other species
A. Pappal

Protecting the marine and freshwater resources of the Northeast from invasive aquatic nuisance species