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Marine Animal Encyclopedia

Oyster Thief Colpomenia peregrina

The oyster thief gets its unusual name from its habit of growing on shells, including commercially grown oysters. The frond is initially spherical and solid, but as it grows, it becomes irregularly lobed and hollow and fills with gas. Sometimes, this can make it sufficiently buoyant to lift the oyster, which is not attached to the seabed, and they may both be carried away by the tide. This seaweed has a thin wall with only a few layers of cells. The outer layer is made of small, angular cells which contain the photosynthetic pigments that give the oyster thief its brown color.

Oyster Thief habitat mapzoom image
  • Kingdom Phaeophyta
  • Diameter Up to 4 in (10 cm)
  • Habitat Intertidal and subtidal rocks and shells
  • Water_temperature 49–83°F (6–28°C)
  • Distribution Coasts of western North America, Japan, and Australasia; introduced in Atlantic