Red Sponge Nudibranch (Rostanga pulchra)

Red sponge nudibranch with eggs on top of red sponge (photo credit: Zoe O’Toole)

Description: The Red Sponge Eating Nudibranch is often likened to a tic-tac being bright red (or orange) and oval and of similar shape when out of the water. They can sometimes have brown or black spots on them as well. When in the water, the gills come out and form a circle on the back side of the nudibranch. They only reach a size of around 1.6 cm.

Red sponge nudibranch in the water (photo credit: Emma Corliss)

Habitat: From Alaska to the Gulf of California, this nudibranch is from from the intertidal to subtidal range and almost always found on red sponge. At Haystack rock, scan the lower parts of rocks for any bright red. If you find any red sponge, be sure to look closely for the tic-tac nudibranch.

Diet: The red sponge nudibranch eats red sponge!

Tide Pool Tidbits:

  • The orange-to-red pigment of the nudibranch is thought to come from the sponge that it eats.

  • While the intertidal individuals of this species are small, the deeper dwelling ones can get almost twice the size - up to 3 cm!

Reference: Walla Walla University, University of Washington