Tritonia diomedia: The Orange Nudibranch


So lets dive right into it.  (That pun will become inherently clear in the next few lines).  Nudibranchs.  My favorite topic and one you can expect to see a variety of and many posts on when I have nothing else to discuss.   Nudibranchs are a shelless gastropod that belongs to the phylum Molluska (Mollusca if your from the USA.  Personally I prefer the European version of Molluska). Little is known about why these creatures lack a shell when their cousins all have one.  There are some who hypothesis that the nudibranchs have always lacked a shell.  There are others who feel they have evolved to discard their shell and take on their current “slug” like appearance.  Current research shows that small pieces of spicule/chitin, can be found in the body tissues of the nudibranch.  Chitin is a chemical that is often found in most mollusk shells. Interesting right?

So how do these little fellas protect themselves with no shell to hide in?!  Well it turns out most nudibranchs are chemically defended.  This chemical ecology is the subject of much research as  secondary metabolites in marine animals (in this case the toxins the nudibranchs have in their bodies) often are the source of new drugs!  These nudibranchs have evolved to in general be very picky eaters.  They on average eat only 1 type of animal.  They tend to steal their toxins and defenses from their food source and incorporate them into their own tissues.  Neat trick.  Some can even steal the stinging cells from jelly fish!

The orange/pink nudibranch

Tritonia diomedea (the pink nudibranch shown above)  Is a deep sea nudibranch that lives off the coast of Baja California and ranges out towards the sea of Japan.  It lives deep in the ocean and typically feeds on a variety of octocorals (soft corals with 8 tentacles around their polyps) Specifically (Renilla sp.) and Ptilosarcus guernyi (the orange sea pen). The orange sea pen Ptilosarcus guernyi (shown to the right)  is chemically defended with a toxin known as ptilosarcenone.  Found by a Dr. Jack Wekell in 1973,  ptilosarcenone is a terpenoid brirane (think molecule kinda like turpentine and subsequently its chemical formula is the title of this blog).  These nudibranchs feast upon this sea pen like locusts to a field of crops.  They only have one predator too!  A sunflower sea star.  They also have this really cool escape mechanism of this sort of back and forth swimming motion that is 90% effective at helping them to evade predation.  Neurologists call this the “swim escape response”.

Tritonia diomedia is actually used quite extensively in all sorts of research!  Neurologists love it because of its simple neurons and its huge brain and therefore use it as a model to study memory, (the Nobel prize was given to a man who researched this sea slug and determined the biochemistry behind memory formation).  They also look at things like learning, locomotion, and in my particular case chemical ecology, chemo taxis and pharmacology. Unpublished data on these actually shows they even have pieces of iron in their cells that help them to potentially orient to the earths magnetic fields!!! Pretty cool stuff.  BTW those bunny ear looking things are their nose and are known as rhinophores.  These little guys are effectively blind.  Future research will hopefully teach us a lot not only about our own neurological design but also about this wonderful creature as well.

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Posted on November 11, 2009, in Scientific Research and tagged , , , , , , , . Bookmark the permalink. Leave a comment.

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