Goniobranchus geminus

Image courtesy of Marc Chamberlain
Port Ghalib, Marsa Alam along the Southern Red Sea Coral Coast, Southern Red Sea, Egypt
Goniobranchus geminus (Rudman, 1987)

This is one of those mantle flapping chromodorids that raise and lower their mantle rhythmically, presumably for the purpose of increasing respiration. The body is yellow with four bands around the mantle edge, the outermost is white, followed by greyish-purple, then bluish-white, then yellow. The middle of the dorsum has numerous purple-brown spots ringed with bluish-white.

Considered a member of the "Risbecia tryoni color group" it is similar to Goniobranchus tritos which may be a color form of G. geminus.

Great shot Marc!


Rudman, W.B. (1987) The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: Chromodoris epicuria, C. aureopurpurea, C. annulata, C. coi and Risbecia tryoni colour groups. Zoological Journal of the Linnean Society, 90: 305-407.

Dave Behrens
Sammamish, WA 98074
Jan., 2023
Send Dave email at davidwbehrens@gmail.com

Marc,and Michelle Chamberlain
Marc and Michelle Chamberlain reside in the Pacific Northwest in Seattle, Washington where they have lived for the last 15 years. They enjoy cold water diving and take advantage of their location to dive Puget Sound, Hood Canal, the San Juan Islands and the Olympic Peninsula all in Washington as well as multiple locations in British Columbia and southeast Alaska whenever possible. They also travel abroad (pre-pandemic), often combining land and water opportunities as in a trip to New Zealand, where they did extensive bird watching and hiking in addition to diving the Poor Knight's Islands (which I am going to put on my places to visit list).

Marc has a Nikon D500 in a Subal housing with 2 YS-D2 strobes and diffusers in addition to a variety of lenses.

Marc in his time in San Diego was SDUPS Photographer of the Year so many times that I lost count! In fact, Marc came to mind many summers ago during a trip on the Catalina Express from Dana Point. Due to a loading snafu, the bag containing my camcorders was stowed down below and therefore unavailable during the hop over to Catalina. Well, you guessed it!, a Blue Whale breeched about 50 feet off the boat and hung around for about 10 minutes for everyone onboard to get a shot. That is with the exception of yours truly! During the remainder of the voyage the only thought that came to mind was "if Marc has been onboard he would have been ready." That folks is the difference between those who dream and those who actually do it!

Send Marc email at marccchamberlain@gmail.com

From left to right, Terry Gosliner, Angel Valdes, Dave Behrens La Jolla, Calif.

Send Dave email at davidwbehrens@gmail.com

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