Slimy Slug, Tambja abdere

Slimy Slug, Tambja abdere. Underwater photograph taken in Zihuatanejo Bay, Guerrero, December 2019. Photograph courtesy of Maude Jette, Dive Zihuatanejo, www.Divezihuatanejo.com. Identification courtesy of Bob Hillis, Ivins, Utah.

Slimy Slug, Tambja abdere. Underwater photographs taken in coastal water off Isle Colorado, Baja California Sur, May 2023. Photographs and identifications courtesy of Dr. Tom Bartol, Carlsbad, California.

Phylogeny:  The Slimy Slug, Tambja abdere (Farmer, 1978), is a member of the Polyceridae Family Nudibranchs. The genus Genus is one of twenty-six genera in the Polyceridae Family, and there are twenty-eight species in the Tambja Genus. In Mexico they are known as Babosa Viscosa. This species was first described by Wesley M. Farmer, a marine biologist, author, and artist from San Diego. Farmer specialized in Opisthobranch mollusks of the Eastern Pacific, beginning his work in the 1960’s. He described at eleven species during his career, which is quite remarkable given the recentness of his work.

Morphology: Slimy Slugs are soft-bodied gastropods that lose their shells during their larval phase. They have a thick mantle on their back (dorsal surface).  Their gills consist of feathery plumes that encircle the anus. They have rhinophores (horn-like projections) on their heads. Rhinophores are chemosensory organs help them to locate food and potential mates. They lack complex eyes, but have photoreceptors that sense light and dark. Slimy Slugs may vary considerably in coloration. They are turquoise or green, with yellow or ochre lines, spots, or dashes. A black line borders these markings. The rhinophores may be dark blue or banded with dark blue and white. The gills are tipped with dark blue, and they are based on yellow stalks. Slimy Slugs reach a maximum of 8.2 cm (3.2 inches) in length.

Habitat and Distribution: Slimy Slugs are found on, and under, rocks at depths between 3 m (10 feet) and 60 m (200 feet). They  are a tropical Eastern Pacific species that are found in all Mexican waters of the Pacific Ocean with the exception that they are absent from north of Magdalena Bay, Baja California Sur, along the central and northwest coasts of the Baja Peninsula and north of Isla San Pedro Nolasco, Sonora, in  the Sea of Cortez.

Diet: Slimy Slugs prey on erect bryozoans and encrusting bryozoans of the Sebugulassi Genus.

Predators:  Slimy Slugs are prey for the Sea Tiger Nudibranch, Roboastra tigris. As a defense mechanism, Slimy Slugs secrete large amounts of mucous when attacked. This slimy mucous is what gives them their common name.

Reproduction:  Slimy Slugs are simultaneous hermaphrodites (having both male and female reproductive organs). Reproduction is sexual, with internal fertilization. Mating is accomplished by two individuals aligning themselves so that they lock onto each other with their gonopores (structure on their right side that is usually retracted). Both individuals become inseminated. The eggs are laid as a string-like mass. The eggs hatch into veliger larva and later metamorphose into adults.

Ecosystem interactions: Slimy Slugs are a poorly studied and understood species. Their commensal, parasitic, and symbiotic relationships have not been documented.

Human Interactions:  Slimy Slugs 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:  Tambja fusca.