Blue-striped Tambja, Tambja eliora

Blue-striped Tambja, Tambja eliora. Underwater photographs taken in Bahía La Ventana, El Sargento, Baja California Sur, March 2022. Photographs courtesy of Aaron Woodrow, Juneau, Alaska. Photographs and identifications courtesy of Aaron Woodrow, Juneau, Alaska.

Blue-striped Tambja, Tambja eliora, Preying upon Leafy Green Bryozan, Sessibugula translucens. Underwater photographs taken in Bahía La Ventana, El Sargento, Baja California Sur, March 2022. Photographs courtesy of Aaron Woodrow, Juneau, Alaska. Photographs and identifications courtesy of Aaron Woodrow, Juneau, Alaska.

Phylogeny:  The Blue-striped Tambja, Tambja eliora (Marcus & Marcus, 1967), is a member of the Polyceridae Family Nudibranchs. The Tambja 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 Dórido de Líneas Azules. The genus name Tambja refers to a region in Victoria Australia, though no one seems to know the connection between that region and the Tambja Genus. The species name eliora has been reported to be derived from folkloric names for seals.

Morphology:  Blue-striped Tambja are a small statured 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. Blue-striped Tambja may vary considerably in coloration but are an easy straight-forward identification. They have an olive-green body with bright-blue longitudinal lines with black margins. The gills are black with a blue line along the inside edge of the rachis. The outside edge of rachis is khaki or yellow ochre at base, and blue at tips. Note:  southern populations of the Blue-striped Tambja found form Oaxaca to Ecuador of this species has the blue lines replaced by a series of elongated spots, and might be a different species. Blue-striped Tambja reach a maximum of 8.0 cm (3.1 inches) in length.

Habitat and Distribution: The Blue-striped Tambja is a benthic organisms typically found in shallow subtropical marine environments and rocky reefs, often in areas experiencing substantial surge or wave action, 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 the west coast of the Baja Peninsula and south of Puerta Vallarta along the west coast of the mainland. Regionally they can be very common on a seasonal basis. There is a similar appearing version of this species that ranges from Oaxaca south to Ecuador that might be a different species.

Diet:  Blue-striped Tambja prey on colonial, filter-feeding bryozoan, the Leafy Green Bryozan, Sessibugula translucens. They are virtually always found perched directly on or adjacent to these specific bryozoan colonies.

Predators:  Blue-striped Tambja are a known prey for the Sea Tiger Nudibranch, Roboastra tigris. As a defense mechanism they utilize swimming by flexing its body from side to side and ride currents to safety. They also utilize camouflage, taking on the coloration of its prey to remain cryptic while feeding on substrate.

Reproduction:  Blue-striped Tambja 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:  Blue-striped Tambja are a poorly studied and understood species. Their commensal, parasitic, and symbiotic relationships have not been documented.

Human Interactions:  Blue-striped Tambja have no direct impact on human activities. They are utilized by the aquarium trade at a nominal level. From a conservation perspective they have not been formally evaluated however they are fairly common regionally with a relatively wide distribution and should be considered to be of Least Concern.

Synonyms:  Nembrotha eliora and Nembrotha hubbs.