California Chromodorid, Felimare ghiselini

California Chromodorid, Felimare ghiselini. Collected from a tidal pool in the greater Agua Verde area, Baja California Sur, March 2020. Collection and photography courtesy of Barry Mastro, Escondido, California.

Phylogeny:  The California Chromodorid, Felimare californiensis (Bergh, 1879) is a member of the Chromodorididae Family of Nudibranchs. The genus Felimare is one of sixteen genera in this family, and there are forty-four species in this genus. This species is also called the California Blue Dorid. In Mexico it is known as chromodorido de California.

Morphology: California Chromodorids have an elongate oval outline, with a moderately long, tapering, tail. They are royal blue to midnight blue in color, with numerous small, to very small, yellow spots. The rhinophores and gills are very dark blue. The gills have yellow spots on their proximal surface. California Chromodorids reach 9.0 cm (3.5 inches) in length.

Habitat and Distribution: California Chromodorids are found on and under rocks. They live from the low intertidal zone to a depth of about 30 m (100 feet). In Mexican waters, this species in found along the West coast of the entire Baja Peninsula. It is found in the central and southern Gulf of California. Many individuals from within the Gulf are darker blue with smaller spots than West coast specimens. This originally lead to some confusion with the Gulf variety being classified as a separate species, Felimare Ghiselini. Subsequent DNA testing revealed the genetic difference too slight to be considered a separate species. This species ranges north to Monterey California. It was extirpated from the northern part of its range, disappearing completely from California by 1984. It reappeared beginning in 2003 and is now found in a few isolated places in California. It remained throughout its Mexican range.

Diet: California Chromodorids are predatory spongivores, eating sponges from the genera Dysidea, Halichona, and Stelleta. They are equipped with large radular (rasp-like) teeth to assist with that process. They can store toxins from their prey in glands in their mantle. This makes them toxic or distasteful to predators.

Predators:  The California Chromodorids has the ability to store toxins from their prey which helps them avoid predation by many predators. There are records of various fish, crabs, fish, sea anemones, starfish and polychaete worms attempting to consume Chromadorids, but they stop after a taste, or disgorge the animal after several hours. Despite this defense mechanism Chromodorids are prey for other nudibranch species.

Reproduction: California Chromodorids are simultaneous hermaphrodites (having both male and female reproductive organs at the same time). Reproduction is sexual, with internal fertilization. The eggs are laid as a sticky string on the surface of the reef or other hard surface. Neither parent tends or protects the eggs. The eggs hatch into planktonic larva and then settle to the bottom to begin benthic life.

Ecosystem Interactions: The commensal or parasitic relationships between California Chromodorids and other species have not been well documented.

Human Interactions: California Chromodorids have very little impact on human activities, other than some aquarium collecting. The temporary extirpation of the species from California for almost two decades may have had some connection to human activities. Theories related to anthropogenic ocean warming have lost credibility since the species has made some recovery. Water pollution may have been responsible for impacting the species, either directly, or by impacting its sponge prey. Again, the subsequent recovery, and the geographic limits of the extirpation event, make this theory unlikely. El Niño weather events could have caused a temporary increase in both water temperatures and pollution from urban runoff within the extirpation region, with less impact on the Baja Peninsula, but that is speculation. At this point there is no direct connection to human activities. The California Chromodord has not been formally evaluated from a conservation perspective. They are widely distributed, but still fairly rare in the northern portion of their range, and should therefore be considered a species of Concern.

Synonyms: Chromodoris calensis, Chromodoris californiensis, Chromodoris glauca,  Chromodoris universitatis, Felimare ghiselini, Hypselodoris californiensis, and Hypselodoris ghiselini.