Friday, December 14, 2012

Five of the Coolest Nudibranchs plus a Freebie

I've decided to start posting about some of the coolest critters you'll find in the Oceans, there is a ton of taxonomic and evolution weirdness that is just not talked about nearly enough.

So here is a list of the five coolest Nudibranchs in my opinion. There are definitely more colorful Nudibranchs out there, but in terms of morphological weirdness/interest these are kind of at the top.

1) Tethys fimbria

Photo cred Dominique Horst (
This thing is just weird. It is the only species within this genus, and frankly nothing else looks like it. It is related to the predatory Melibe, itself an interesting animal in that it actively hunts copepods and other tiny shrimp-like crustaceans by enveloping them in their giant oral hood. Like a diabolical fishing net, or an aquatic venus flytrap. Here is a video for you to get an idea of how Melibe hunts.

Creepy. Tethys feeds in the same manner, which would be cool enough by itself. But then you realize how BIG Tethys can get - almost 30 cm. Nudibranchs usually don't get much bigger than 10cm, and the colorful ones are tiny. 30 cm is massive for an invertebrate, especially for a shell-less organism like Tethys. Finally, the thing reminds me of a trilobite. Look at this video; coming up to it, it looks like we are entering a primordial coral reef. Interesting example of convergent evolution in terms of body shape (maybe?) who knows, maybe trilobites used their head to entrap small organisms.
2) Dendronotus comteti

Valdes et al. 1998

I've written about this nudibranch before (Dendronotus comteti), and I am still fascinated by its biology. It's no looker, but it is the only nudibranch to be found at hydrothermal vents (and I think the nudibranch found at the greatest depth - not sure about that one). Anything found at depth and in such an extreme environment is already of special interest, but to have one species representing an entire Order (which is a lot of species) is quite impressive. I believe that there must be more species of Nudibranchs down on hydrothermal vents/cold seeps/what have you, but so far this is all we have.

3) Hermosita hakunamatata

Photo cred Peter Ajtai
 It's a nudibranch named after the Hakuna Matata. Enough said.

4) Onchidoris bilamellata

Photo cred Me. Yay!
 Onchidoris bilamellata is (or was) my pet project/nudibranch species for a while. It is unique in that it can be found in huge numbers here in the Northeast (especially in Maine where I did a project on their biogeography in high school five years ago. I've typed up the entire report on a google site for all to see. Please excuse the layout/scientific methodology used; I was 14 when I started the project Check it out!!) Fascinating life history, and because they have spawning aggregations in such great numbers, it is relatively easy to find them and study their behavior.

5) Glaucus atlanticus

 Any list of any nudibranchs has to cover G. atlanticus. This are undoubtedly the funkiest nudibranchs out there - They adhere to the ocean surface via surface tension (you are seeing the oral side i.e. the belly in this picture - they float upside down) and munch away on Physalia physalis, or the Portuguese Man O' War, an extremely nasty hydrozoan (not a jellyfish as many people think). These nudibranchs are able to avoid being stung and even use the stinging nematocysts found within the Man O' War tentacles to their own advantage by ingesting them and forming their own nematocysts on their cerata. Gorgeous animal, definitely by top 1 nudibranch to see alive. FREEBIE - This organism always remind me of Velella velella, or the By the Wind Sailor (also a hydrozoan - and one of the best names for an invertebrate) because it too has a striking blue/white coloration. Like the Man O' War, it too is pelagic but doesn't have a sting felt to humans. Simply a gorgeous animal.
Photo cred A.F. Julien

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