Red Sponge Nudibranch (Rostanga pulchra)
Red sponge nudibranch with eggs on top of red sponge (photo credit: Zoe O’Toole)
Red sponge nudibranch in the water (photo credit: Emma Corliss)
Description: The red sponge nudibranch is often likened to a tic-tac, being bright red (or orange), oval, and of similar shape and size to a tic-tac. 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. Their gills and two rhinophores match the same red color as the body. They only reach a size of around 1.8 cm.
Habitat: From Alaska to the Gulf of California, Mexico, this nudibranch is found from the intertidal to subtidal range and is 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 on top.
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!
References: Walla Walla University, University of Washington