Three-lined Aeolid, Coryphella trilineata

Three-lined Aeolid, Coryphella trilineata. Underwater photograph taken in the coastal waters off San Diego, California, March 2018. Photograph courtesy of Bob Hillis, Ivins, Utah.

Phylogeny:  The Three-lined Aeolid, Orienthella trilineata (O’Donoghue, 1921), is a member of the Coryphellidae Family of Nudibranchs. The genus Coryphella is the only genus in this family, and there are twenty-four species in this genus.  In Mexico this species is known as eolido de tres lineas.

Morphology:  The Three-lined Aeolid has an elongated oval profile with a long tapering tail. They are a beautiful translucent white to grayish color.  The cerata are an orange-red color and found in distinct clusters. They have three opaque white lines that run the length of the dorsal surface for which they are named. The center line splits and extends into the oral tentacles. In some animals the rhinophores and tentacles are tipped with orange. They reach a maximum of 3.6 cm (1.4 inches) in length.

Habitat and Distribution:  The Three-lined Aeolid is found on, and under, rocks and within algae. They reside intertidally and can be found at depths up to 50 m (164 feet).  They are more abundant on a seasonal basis. In Mexican waters the Three-lined Aeolid is a resident of the Pacific, but has a limited range being found only from Bahia Tortugas, Baja California Sur, northward along the central and northwest coasts of the Baja Peninsula, and throughout the Sea of Cortez.

Diet: Three-lined Aeolids feed primarily on polyps of the California Stickhydroid and Eudendrium califoricum and and various Hydroid’s, Tubularia sp.

Predators:  Predation of the Three-lined Aeolids has not been documented specifically, but other species in this genus are eaten by sea stars and crabs.

Reproduction: Three-lined Aeolids are simultaneous hermaphrodites (possessing both male and female sex organs). Reproduction is sexual and fertilization is internal. The mating ritual involves touching, biting, and maneuvering so that one individual can inseminate the other without oneself being inseminated. The eggs are laid in a mass, as a gelatinous, spiraled, ribbon on the seafloor. The eggs hatch into veliger larva, which drift as plankton before settling down to begin their benthic lifestyle.

Ecosystem Interactions:   Any type of commensal, parasitic or symbiotic relationship of the Three-line Aeolid has not been documented.

Human Interactions: Three-lined Aeolids have no direct impact on human activities. From a conservation perspective they have not been formally evaluated however they are fairly common with a relatively wide distribution and should be consider to be of Least Concern.

Synonyms: Coryphella fisheri, Coryphella piunca, Flabellina fisheri, Flabellina piunca, Flabellina trilineata, Orientella trilineata, and Orienthella trilineata.