Roboastra gracilis

Roboastra gracilis Bergh, 1877

This is a long, slender Polycerid with huge, long slender gills and rhinophores. Typical in its narrow body, long pointed tail and longitudinal lines, it is smaller (measuring only to 27mm in length) and more delicate than other species in the family (ie:Tambja affinis and Roboastra arika). It is black with longitudinal gold stripes that meet behind the gill. The three simple gills and long pointed rhinophores are pale green. In some specimens the stripes are broken, forming a series of spots, as in the individual shown above.

The diet of this species is unknown. Common intertidally to about 8 meters deep, it is usually in sheltered waters, this specimen was found crawling on broken coral rubble, the obvious result of dynamite fishing, on a shallow reef flat on Mactan Island, Cebu, Philippines. The literature indicates this species occurrence throughout the tropical Indo-Pacific, from east Africa to Thailand, the Solomons, Indonesia, Philippines, and NSW, Queensland and Western Australia. If Terry wasn't off vacationing in England, he'd say it was another of my "Beginners Luck" finds. Hey Terry.... Naught!

As the specific name implies, the graceful shape and moves of this Princess Di-like species makes it a really exciting find for the biologist-nerd and the diver-photographer alike.

Taxonomic information courtesy of:

David W. Behrens

Author: Pacific Coast Nudibranchs
Co-Author Coral Reef Animals of the Indo Pacific
Propriator of Sea Challengers Natural History Books !

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