Due to a recent 2020 taxonomic study, the Sea Clown Triopha has now been divided into two distinct species: the Triopha catalinae and the Triopha modesta. Most of the species documented here are Triopha modesta, which is now considered to be a trans-Pacific species, found primarily along the coast of British Columbia and Southern Alaska and as far away as Korea and Japan. The Triopha catalinae (to 15 cm) an Eastern Pacific nudibranch, is well established along most of the West Coast of North America but tends to be more common along outer coasts and south of the San Juan Islands. Luckily for the snorkeler/free diver, these species are often found under rock ledges feeding on bryzoans in the intertidal and high subtidal zone. I have also found individuals feeding in the eelgrass, on kelp and on docks. Though I’ve never seen these animals copulating, I have seen them moving into position (right side to right side) and a photo of that is below. For some fun reading on triopha sex, check out Bill Rudman’s comments on their genital apparatus. Like all nudibranchs, triophas are hermaphrodites, but triophas apparently have two female ducts, rather than the usual one. For more information on telling the difference between the T. catalinae and the T. modesta, please see Karin Fletcher and Linda Schroeder’s handout on telling the difference, complete with close-ups of the tubercles.
