Mimic Pseudobicerid flatworm

Top image courtesy of Marcel Tanke
Mabul-Sipidan, Malaysia

Chromodoris magnifica

Bottom image courtesy of Jim Black
Anilao, Batantas, Philippines

Chromodoris magnifica (Quoy & Gaimard, 1832) & a Mimic Pseudobicerid flatworm - An Odd Couple

Chromodoris magnifica is one of several, very similarly striped chromodorids bearing black, white and orange, or blue, black, white and orange longitudinal bands. This bright coloration is thought to be aposomatic, or warning coloration. These species are warning wanton predators that they maintain a highly effective chemical defense system. These chemical metabolites and the role of aposomatism as both an offensive and defensive strategy have recently been meticulously reviewed by Cimino & Ghiselin, 2009 .

As one might expect, others species of reef invertebrates have, over millions of years, been selected for survival by mimicking animals with such a warning/defense system. Looking very similar to a toxic model gains you protection from predators that have all ready made the mistake of tasting the nasty one, and learned to avoid it. Notably, there are three species of polyclad flatworm, one shown above with its C. magnifica model, that are believed to use their mimic coloration for defense. Photographs of both are also found on page 157 of Nudibranch Behavior . The two others (actually there may be more yet to be discovered) can be seen in BOW Week 3 and the other on page 110 of Coral Reef Animals of the Indo-Pacific .

Although it has not been determined if these three flatworms might also defend themselves chemically, like other flatworms that have been studied, we know from Cimino & Ghiselin that chromodorids in this color group contain chemical metabolites called rearranged spongiane diterpenoids, which are produced by bacterial symbionts in the sponges they feed on. If you would like more detailed information about the specific metabolites and the sponges they come from, I refer you to the monograph cited above

Dave Behrens
Gig Harbor, Washington
Feb., 2010

Marcel and wife Marion

Marcel and Marion presently again live in their native country, the Netherlands. They started diving during the 14 years that they lived in China and Korea. Marcel has BSAC Instructor diving level. Diving took them pretty much all over Asia and many other places. Nudibranchs became their main interest after several trips to the Philippines and Indonesia. Marion is “spotter” for the nudibranchs and Marcel is taking the pictures.

Marcel is still using his “point and click” Canon Ixus 900TI Digital Camera (see http://slugsite.us/bow2007/nudwk586.htm )

Send Marcel email at marceltanke@cs.com

Jim Black on location in Thailand with friend

Jim is retired from 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 D-300 in Subal Housing with Ikelite strobes. Macro Mate on 105mm for supermacro

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 jim.black14@verizon.net

Jim has been a solid supporter of the Slug Site since day one. His countless contributions put him near the top of the list of photographers who have greatly expanded our knowledge of sea slugs. There are a lot of kids in the formative stage of their education who are getting their first introduction to our sea slug friends via the great photographs Jim and other contributors have made to the site. My hat is off to Jim for making this presentation possible!

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

Send Dave email at dave@seachallengers.com
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