The Sea of Cortez is Riddled with Nudibranchs

Being the kiss of death that I am when it comes to dive trips and good conditions, I shouldn’t have been surprised when we arrived in the Sea of Cortez to find cold, green, murky, Socal-esque water. For months prior to the trip, I entertained fantasies of seeing whale sharks, hammerhead sharks, orcas, manta rays, bait balls, marlin… you know, all the things I didn’t see, the things that everybody else sees diving the Sea of Cortez so long as I’m not there.

But when you’re on a fantastically luxurious ship in the middle of nowhere with a wonderful group of people, it certainly doesn’t pay to wallow in disappointment. We San Diego divers are conditioned to semi-permanently affixing our macro lenses to our camera bodies and letting the dome ports and fisheyes collect dust for that rare good-visibility day, and so it was easy to fall back into that routine on our ill-fated dive trip and go hunting for the little stuff.

And so the Sea of Cortez Nudibranch Project was born.

Having never been quite such a captive audience to bad conditions prior to this trip, I was actually pretty blown away to discover just how many nudibranch species one will find on twenty consecutive macro dives. I believe we counted at least 17 different opisthobranchs, several in large numbers, and I even got decent photos of most of them. And we can all rest assured that while I spent a week with my head in holes, the manta rays and their elusive brethren were probably SWARMING just out of sight. Swarming.

 

 

Tambja nudibranchs and the dorids who love (to eat) them

Speaking of swarming, the Sea of Cortez was literally crawling with these little Tambja nudibranchs. They were everywhere! And this was fabulous, because they are just so cool to look at and they came in a lot of color configurations. I saw so many of them, I even came to have favorite anatomical parts of them. Like the gills. I really think their gills look cool.

Oh, and if I get any of the identifications wrong, and you feel inclined to correct me, please do. The ID book was in Spanish!

Just when we thought we had had enough of the Tambja clones, along came the Godzilla of nudibranchs: Roboastra tigris. This monster was a whopping 5 inches long and had a giant, gaping mouth with which he was efficaciously Hoovering all the food in sight.

Aside: I’m obsessed with sea monsters. OBSESSED. So you can bet that if it lives underwater and it’s bizarre, slimy, or atypically large, I’m all over that. And likely to be squealing and flailing maniacally. As I was upon discovering this gem of a slug:

If you look closely, you can see a parasite hitchhiking on his rhinopore:

And just when I had tired of NudiZilla, I found a bigger one:

Apparently, however, the specimens I saw don’t even come close to how big these suckers can get: 30cm is the longest recorded length. Also apparently, had I stuck around long enough, I might have borne witness to one of these monsters dining on a Tambja specimen!  I read, now, that carnivorous and predatory Roboastra prefers to eat Tambja nudibranchs by grasping them in its mouth and swallowing them whole.

 

And now for something a little less gory

This isn’t a nudibranch at all. It’s a snail. It’s cute! It probably eats plants.

 

Other opisthobranchs of the Sea of Cortez that are not nudibranchs

We know all about sapsucker slugs from Curaçao, right?

(Right? Okay, read this, then. I’ll wait.)

Well here are some more.

Based on its appearance, I was not at all surprised to learn that Diomedes’ sapsucker (Elysia diomedea) was closely related to the E. crispata slugs found all over Curaçao. As members of Sacoglossa, both species of slug exhibit kleptoplasty, which basically means they continue to use the photosynthetic power from the plant chloroplasts they ingest for their own energy purposes, and can switch back and forth from active feeding to photosynthesis depending on food availability. Cool, right?

And here’s a Navanax. We have Navanax here in San Diego, but they look a little different. This one is laying eggs.

 

And finally, the actual Sea of Cortez nudibranchs

 

I thought the texture on these Glossodoris sedna nudibranchs was especially pretty.

 

I love that the translucence of this Chromodoris marislae lets you see its guts.

 

I was looking specifically for this Hypselodoris agassizii! I did a little shriek of joy when I finally found one near the end of the trip.

 

This Hypselodoris ghiselini reminds me of a curious bunny rabbit.

 

These Flabellina marcusorum nudis were super tiny, but once we found the first one, we realized they were everywhere.

 

We get Spanish Shawls (Flabellina iodinea) en masse here in San Diego. I think that’s why it was so cool to find some so far from home!