Encrusting Coralline Algae (Lithothamnion spp. and other genera)

Lined chiton on encrusting coralline algae (photo credit: Katie Corliss)

Encrusting coralline algae (pink) growing on acorn barnacles (photo credit: Zoe O’Toole)

Description: Encrusting coralline algae varies in color from light pink to light purple. The crust is very thin, only 2 mm, and almost appears as a discolored part of the rock it’s on.

Habitat: As an encrusting algae, it can cover any hard surface from rocks to shells or even barnacles. Encrusting coralline algae is found around the world - while the specific species may differ, the appearance is similar and hard to differentiate with the naked eye. They are mostly found in the low intertidal zone to shallow subtidal zone.

Tide Pool Tidbits:

  • Chitons and some limpet species feed on encrusting coralline algae.

  • Some species of encrusting coralline algae secrete a chemical to deter epiphytes (other animals growing on top of them) while others can shed their top layer to rid themselves of epiphytes.

References: The New Beachcomber’s Guide to the Pacific Northwest by J Duane Sept, Aquarium of the Pacific