Halgerda okinawa

Image courtesy of Zeineb Alhaidari
Lembeh Straits, Indonesia
Halgerda okinawa Carlson & Hoff, 2000

Friends Clay and Patty Jo named this species in 2000 after receiving species from Bob Bolland, in Okinawa - hence its trivial name.

Interestingly, this brightly colored species, is the largest of all the members of the genus. The gorgeous photo above by Zeineb Alhaidari was taken in Lembeh Strait, and the animal was described as being the width of a man's fist, or about 15 cm. Wow!

One page 179 of Indo-Pacific Nudibranchs and Sea Slugs. Terry, Angel and I present a fantastically beautiful specimen photographed by Jim Black . This specimen was about 11 cm in length. This species is characterized by its yellow tubercles gill, with thick black marks and between the dorsal ridges.

San Diego diver Mike Poirer , also diving Lembeh, took this fantastic photo of a pair, more orange in color, but most importantly showing how in some specimens, the black coloration forms circles in the depression between the dorsal ridges.

Although little is known about the life history of this species, Cimino & Ghiselin (2009), in their astonishing monograph titled Chemical Defense and the Evolution of Opisthobranch Gastropods , report that obviously, like H. okinawa , many species of Halgerda display aposomatism, or warning coloration, telling potential predators that their bodies contain caustic, distasteful chemicals. Although, the identity of these chemical metabolites has not been identified for H. Okinawa, several other species contain alkaloids from sponges they feed on. As different species have differing levels of different cytotoxins, the authors suggest - "The genus is a good example of the continued adaptive radiation of tropical dorid nudibranchs."


Carlson, C.H. & P.J. Hoff. (2000) Three new Pacific species of Halgerda (Opisthobranchia: Nudibranchia: Doridoidea). The Veliger 43(2):154-163.
Cimino, G. & Ghiselin, M., 2009. Chemical Defense and the Evolution of Opisthobranch Gastropods. Proceedings of the California Academy of Sciences. Series 4, Vol. 60:10, pp 175-422.

Dave Behrens
Gig Harbor, Washington
Nov., 2009

Zeineb Alhaidari
I am a veterinarian , specialized in dermatology , living in the south of France , on the Mediterranea seashore. I started diving end of 2001 , and realized it was a wonderful way to get away from stress. I became addicted , and developed an early interest in marine biology , this giving me "better eyes". I came to underwater photography with some reluctance two years ago , pushed by some fellows photographers , but I soon realized how nice it was to share what I had seen with friends , and that it was a more reliable way to describe the encounters than memory alone. I try whenever possible to combine my passion for diving with my passion for travelling . My camera is a Nikon coolpix P5000 with an Ikelite housing , and I started to use an external strobe just recently. I am still at the stage where I shoot at everything with enhusiasm , and I know that I have to work to improve my photographic skills , but now , I am hooked , and the Mediterranea sea , which is my backyard is an absolutely wonderful and endless game field.

Send Zeineb email at z.alhaidari@wanadoo.fr


Don't know about you folks, but judging from her photo, I would say Zeineb is off to a great start in her underwater photography career!

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

Send Dave email at dave@seachallengers.com

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