Gymnodoris rubropapulosa

Photo courtesy of Jim Black
Anilao,Batangas, Philippines
April, 2005

Gymnodoris rubropapulosa (Bergh, 1905)

What can I say, Jim Black has once again stepped up to the plate and hit one out of the park! Jim's photo of Gymnodoris rubropapulosa puts to rest forever a common misconception that nudibranchs are for the most part,inanimate, uninspiring photography subjects. Jim's photo depicts one of the most voracious predators in the nudibranch world finishing off what looks to be Ceratosoma tenue while at the same time portraying a commensal relationship with the imperial shrimp perched on its back, who is probably along for the ride and any scraps that may come his way as the result of hitch hiking!

All members of the genus Gymnodoris are “slug-a-vores” feeding on a number of species of nudibranchs. Some species, including G. rubropapilosa , will even cannibalize their mate after copulation. Even more bizarre, some have been observed trying to swallow their mate during mating. Go figure. See NUDIBRANCH BEHAVIOR , pages 108-109, for more details.

This species coloration, gaudy bright orange clown spots on a clean white background, is very obviously aposematic, advertising the fact that it maintains a chemical defense system to ward off predators. This system of acid glands, located along the margin of the notum, secrete caustic chemicals when the dorid is disturbed.

While ceratosomids, bear a chemical defense system also, Gymnodoris seems immune to it as evidenced by this attach. This is interesting as field observations have documented that some gymnodorids will not eat other chemical bearing species.

Finally the presence of the commensal Imperial Shrimp, Periclimenes imperator . Members of this shrimp genera have a commensal relationship with other invertebrates ranging from sea anemones, sea urchins and seastars to sea slugs. The shrimp seem to clean debris and parasites off the notal surface of the slug. When on the Spanish Dancer, they keep the gill free of fecal pellats. See Nudibranch Behavior, pages 165-166.

And folks think nudibranchs just sit there an do nothing. Naut.

Dave Behrens
Gig Harbor

Jim Black in cockpit

Jim is currently on medical leave with US Airways after 27 years as a pilot..., flying Captain on an Airbus 330 Internationally.

Diving since 1970...with over 5200 dives logged. Shoots Nikon F4s in housing and Nikonos RS.

Jim's photography has been featured in a number of books and publications including Helmut Debelius' Nudibranchs and Sea Snails of Gosliner, Behrens and Williams Coral Reef Animals of the Indo-Pacific. A photo of Jim petting a shark in "Sleeping Shark Caves" off Isla Mujeres Island, Mexico, taken by Amy Foster his significant other, recently appeared in Dave Behrens' Diving Guide to Cozumel, Cancun & The Riviera Maja.

Send Jim email at

Puerto Vallarta, Mexico
March 2005

Ali Hermosillo and Dave Behrens

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

Send Dave mail at

© The Slug Site, Michael D. Miller 2006. All Rights Reserved.