Chromodorididae Family of Nudibranchs

Phylogeny:  Nudibranchs of the Chromodorididae Family are known as the Chromodorids are Sea Slugs in the Phylum Mollusca. The name chromodorid means “colorful dorid”, which indicates the wide variety of colors and patterns they display. They are in the Class Gastropoda and the Order Nudibranchia.

Distribution: Chromodorids are found worldwide, in tropical and temperate waters. There are between three hundred and three hundred and sixty members in the Chromodorididae Family of which sixteen species are found along the west coast of Mexico. Chromodorids are found on, or under, rocks, in crevasses, and on vertical and overhanging surfaces. Most Chromodorids are found intertidally or subtidally at depths up to 30 m (98 feet), either because it is the actual depth limit, or because most observations are made by SCUBA divers.

Morphology:  The Chromodorids are soft-bodied gastropods that lose their shells during their larval phase. These nudibranchs have “naked gills” exposed on their backs that are utilized to separate these Chromodorids into two main classifications, the Aeolids and the Dorids. The Aeolids have a mantle that forms a series of finger-like projections (cerrata) along the entire back of the animal; these cerrata function as gills that assist with digestion, and they can incorporate stinging cells, from their prey, that they utilize for defense. The Dorids have a thick mantle on their back (dorsal surface) that extends over the foot; their gills consist of feathery plumes that encircle the anus. They have an elongated oval profile with a mantle that extends well beyond the foot. The mantle is usually smooth, though some species have sparse, low tubercles. Their heads have flattened oral lobes, that resemble tentacles, around the mouth that assist with feeding. The anterior portion of the foot (propodium) is composed of two thin layer (bilaminate) and not notched at the mid-line. All chromodorids have lamellate (scaly) rhinophores (horn-like projections) on their heads that are chemosensory organs that help them to locate food and potential mates. Chromodorids are cryptobranchia, indicative that they can withdraw their gills in to a special compartment, to protect them from being nipped by predators. They lack complex eyes, but have photo-receptors that sense light and dark. Despite their inability to see color, nudibranchs are some of the most brightly colored of all animals deriving the pigments for their color from the food they eat. The Chromodorids reach a maximum of 30 cm (11.5 inches) in length but most are less than 2.0 cm (0.8 inches).

Ecosystem Roles:  The Chromodorids feed on sponges utilizing large radular (rasp-like) teeth to assist with that process. They can store toxins from their prey in glands in their mantle that makes them toxic or distasteful to predators. There have been documented sightings of various crabs, fish, polychaete worms, sea anemones and starfish attempting to consume Chromodorids, but they stop after a taste, or disgorge the animal after several hours. Despite this defense mechanism, Chromodorids are preyed upon by other nudibranch species.

Reproduction:  Chromodorids are hermaphrodites being able to play the role of male or female that increases their chances of reproducing when mates are few and far between.