Posts in Category: Slugs in Nature

Photos and descriptions of sea slugs in their native habitats. May include some nearby residents.

Bonaire Photos: More

We are just about to post the photos of the setup process of the improved Box of Slugs 1.0, which will be known as BoS 1.1.  It will have two broodstock tanks, a hatchery and a sump/Bryopsis storage tank.  In the meantime, here are a few more photos from the January trip to Bonaire.  Nothing to do with slugs, but the photos are at least of marine organisms.  I hope you enjoy them.  As always, click on the images to enlarge.

Longlure frogfish on Bari Reef, Bonaire.

Longlure frogfish on Bari Reef, Bonaire.

Hawksbill and small green turtles on Bari Reef, Bonaire.

Hawksbill and small green turtles on Bari Reef, Bonaire.

Brain coral, Bari Reef. Joanna in background.

Brain coral, Bari Reef. Joanna in background.

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Coney seabass on sponge, lobster antennae extending from hole in background. Bonaire.

Healthy colony of staghorn (Acropora cervicornis). Bonaire.

Healthy colony of staghorn (Acropora cervicornis). Bonaire.

Sand diverlizardfish, Andrea I, Bonaire.

Sand diver lizardfish, Andrea I, Bonaire.

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Lionfish, Bonaire

Foureye butterfly fish, Salt Pier,Bonaire.

Foureye butterfly fish, Salt Pier,Bonaire.

Colorful Mussa coral, windward side of Bonaire.

Colorful Mussa coral, windward side of Bonaire.

 

Whitespotted filefish, Bari reef, Bonaire.

Whitespotted filefish, Bari reef, Bonaire.

Balloonfish, Andrea I, Bonaire.

Balloonfish, Andrea I, Bonaire.

Jawfish near mooring buoy, Alice in Wonderland, Bonaire.

Jawfish near mooring buoy, Alice in Wonderland, Bonaire.

Gorgonian scene, Bonaire.

Gorgonian scene, Bonaire.

Longsnout seahorse (Hippocampus reidi), Salt Pier, Bonaire.

Longsnout seahorse (Hippocampus reidi), Salt Pier, Bonaire.

Voracious iguana, Slaagbaai National Park, Bonaire.

Voracious iguana, Slaagbaai National Park, Bonaire.

Origin Myth, Part 2

At the end of Part 1, I had discovered Elysia diomedea, and the seed was planted about diverting possible future research toward marine organisms.

A lot of changes were occurring before and during 2012.  The event that probably had the most impact was the death of my long-time mentor and Lab Chief, Howard Nash, in 2011.  Aside from the emotional consequences of such a loss, there were also the practical details associated with the closure of the lab.  Papers needed to be finished, and I needed to chart the next stage of my career.

Howard Nash, pushing flies

In retrospect, it was a great opportunity to ask myself what I would do if I could do anything I wanted.  Well, almost anything.  Astronaut or dinosaur hunter, for example, were pretty much off the table.  In the end, the direction that most excited me was teaching at the university level, hopefully with the possibility of sneaking in a little research with the undergraduates.

As luck would have it, a lecturer position in physiology and neurobiology (my two areas of expertise) opened at the Universities at Shady Grove campus of the University of Maryland College Park.  I was pleased, relieved, and amazed to be offered the position, and then overwhelmed with the amount of work that it took to do a credible job teaching undergraduate lecture and lab courses.  In the back of my mind, though, I continued thinking about involve students in studying an interesting and relevant question.

One of the first questions regarded which organism to study.  I had spent the previous 20 years or so studying Drosophila, which is a marvelous organism with an enormous experimental toolkit.  It is also extremely small (not so good for most aspects of neurophysiology) and is being studied by close to a gazillion people.  Hard to find a niche for a shoestring operation in that melee.

I had become excited about Nematostella, a little mud-dwelling anemone that is becoming an increasingly popular model organism for the study of development, genetics, and evolution of cnidarians.  These animals have a simple nervous system that may resemble that of our earliest multicellular ancestors.  It seemed like studying the activity and connections in the nervous system could provide fundamental insight into how nervous systems evolved.  They are easy to keep, and the Nematostella community is very enthusiastic and supportive.  Recording electrical activity from the teeny neurons in the Nematostella nervous system, however, was somewhat more ambitious than was practical with the available resources.

Nematostella vectensis, May 2011.

Nematostella vectensis, May 2011.

Elysia should have been the obvious choice from the beginning.  They are sizable molluscs, and molluscs are known for large, easily identifiable neurons that are accessible to relatively simple recording techniques.  There was even a small literature regarding neurobiology of E. chlorotica.  Furthermore, E. chlorotica had been reported in the Chesapeake Bay, so it seemed like an excellent way of making a connection between work in the lab on campus and the local ecology.

A plan was forming: Behavior and ecology with E. diomedea in Bahia, physiology and ecology with E. chlorotica in Maryland.

After finishing the 2014 spring semester at UM, I was again lucky enough to be able to join Ocean Discovery at Bahia de los Angeles.  Professional and personal obligations left me with less time for planning than I would have liked, but I had developed two questions for the trip.  First, is E. diomedea attracted to light, as one might expect of a photosynthetic organism?  This would lay the groundwork for more detailed experiments on spectral preference and neural circuitry.  Second, what does the slug eat?  Surprisingly, that was not (and is still not) known.  Almost all other Elysia species eat green macroalgae, but E. diomedea was rumored to feed upon Padina, a brown alga with which the slug is commonly associated.

The plan was simple: collect a small group of E. diomedea as soon as possible, and perform behavioral assays.  This was to be followed by a workshop in which I would enlist the students to help extract the chlorophylls from the slugs and perform paper chromatography to separate the pigments and compare them to those of local algae species.  I brought my electrophysiology kit, along with some LEDs and a controller for phototaxis assays, and managed (with a lot of help from Dr Talley and several trips to Dixieline Hardware), to collect the solvents, tubes, paper and other items required for chromatography.

Sadly, Drew was unable to travel down to Bahia that year.  That cost me the opportunity to spend time with a friend and colleague, and it meant that he would not be able to supervise the students studying the movement of energy from the sea to the islands (“spatial subsidy,” a.k.a. “Energy Transfer”).  Although I was far from a perfect substitute, I had spent a few summers observing, and had an adequate theoretical overview of the project, so I offered to help out with the students and staff for the few weeks I was there.  (Be patient, this will eventually be relevant to the slug project.)

The silver lining was that I was able to spend every morning out on the islands with the students.  On the trip out, there was something exciting to see almost every morning.   Dolphins, whales, sea lions and whale sharks all greeted us at one time or another.

Sea Lions Basking in Bahia de los Angeles

Sea Lions Basking in Bahia de los Angeles

Plus, the islands themselves were spectacular, and it was invigorating just to be on them.

Ocean Discovery Students on the Island of Fletcha

Ocean Discovery Students on the Island of Flecha, summer 2014.  Jorobado island in Background.

So I got to spend mornings pretending to be a biological oceanographer.  Afternoons were filled with a variety of tasks, but I tried to spend as much time as possible snorkeling in pursuit of Elysia.  (See, I told you we would return to sea slugs.).  Based on how quickly I had found them the previous summer, I fully expected to have a small pile of them in short order.  Strangely, though, there seemed to be none to be found.  I combed areas heavily grown with Padina (the potential food plant mentioned above), other areas with Codium (“dead man’s fingers,” another potential food plant), rocky areas with turf algae, but found no slugs. I looked in the shallows, and as deep as was practical with a snorkel and a few weights.  Nothing.

After almost a week, it became rather distressing.  Reviewing Hans Bertsch’s work on the distribution of opisthobranchs in Bahia de los Angeles, I noticed that there had been a steady decline during the years of his study, which worried me a bit.  Were conditions deteriorating in some way, so that E. diomedea was increasingly scarce in the bay?  Also, he had not mentioned collecting as far south as we were, so maybe conditions were not as good at our field station.  But I had found them the previous year…

The breakthrough came on a day when the students were working at the station, so we did not have to get on a boat to the islands first thing in the morning.  With a little free time, it seemed like a great opportunity for more slug hunting, even if my optimism was starting to fade.  I was pleasantly surprised to find one of the little guys within a relatively short period.  So surprised, in fact, that I had forgotten to bring any sort of container, which led to a comical juggling act of carrying a small, squishy creature back to shore in large clumsy hands.  Given their apparent rarity, the little gal was extremely valuable, and losing her would have been a huge blow.  She made it back to shore, and got her own spacious plastic tub with an airstone for circulation.  For good measure, I added a small rock with a collection of possible food plants.  Below is a photo of her, with a ruler to provide the appearance of scientific rigor.

Elysia diomedea, Bahia de los Angeles

Elysia diomedea, Bahia de los Angeles

The following morning was also available for snorkeling, and I promptly collected three more Elysia.  Although it might have been coincidence, finding four animals during a relatively short period of collecting in the morning, compared to finding zero after several hours of hunting in the exact same area during afternoons, suggests that it was the time of day, rather than the location or long-term trends, that was the important factor in success.

In retrospect, it makes sense that the slugs were most exposed in the morning.  My working model when I started the project was that “solar sea slugs” would be strongly dependent on light, and maximize their exposure by lolling about in the afternoon sun.  Recent work indicates that, despite the presence of kleptoplasts, the slugs depend almost entirely on feeding for their energy and nutrition.  My captive slugs seem to be (note that this is fully anecdotal at the moment) at their most active, especially regarding egg laying and general exploration, in the evening and early morning.  The rest of their time is mostly spent face down in their food plants, like so many squishy, aquatic cows.

The remaining time allowed for a few experiments, including a quick and dirty look at phototaxis and spectral preference.  Unsurprisingly, they are attracted to light, and appear to prefer the long wavelengths, such as the orange shown below.  The experiment was pretty crude, but the results match what had previously been shown for other species.

Elysia on orange LED.

Elysia on orange LED.

This almost closes the genesis of the Elysia project, and gets us just about to the beginning of the Solar Sea Slug Blog.  I left Bahia knowing much more about the behavior and anatomy of Elysia than when I had arrived, and realized that the little slugs were much more complex than would be expected of “crawling leaves.”

Back in Maryland, I was ready to start hunting for local E. chlorotica in the Chesapeake.  An email exchange with Dr. Sidney Pierce, now Professor Emeritus at the University of South Florida quickly disabused me of the idea.  In his opinion, reports of that species, and its food plant, here are dubious.

Perhaps it was just as well.  E. clarki is easily available and easy to fatten up on nuisance algae, and E. papillosa may be smaller, but appears to have similarly broad preferences and a rapid generation time (which will be the subject of a future post).

Slugs of Bonaire

I know you have all been eagerly awaiting the most recent slug photos from our trip to Bonaire.  We had hoped to find some of the less common species, such as E. ornata, E. subornata or E. picta, but efforts to find a local expert to help locate suitable habitats were not successful this time around.  Apparently, not everyone is as fascinated by this marvelous genus of slugs as I am. I gave up rather quickly trying to explain that, yes, I know that lettuce slugs (E. crispata) are common on the western side of the island, and no, I am not looking for colorful nudibranchs.  Easier to nod my head enthusiastically.

Nonetheless, there were plenty of E. crispata to be had, which was just marvelous.  Here are a few of the little beauties we found.  One characteristic of the species in the variability in color, and this group shows a little of the spectrum.  The strobe failed early in the trip, but the slugs’ preference for shallow water provided the opportunity for available-light photography.

Below is a pastel green specimen, found at Margate Bay.

Light green E. crispata.  Bonaire.

Light green E. crispata. Bonaire.

 

These two blue and green fellows were found huddled below a large gorgonian, next to a nice piece of fire coral.  In the shallows of Red Beryl, one of our favorite sites at the south end of the island.

E. crispata and fire coral. Red Beryl, Bonaire

E. crispata and fire coral. Red Beryl, Bonaire

 

Below is “Tridachiasaurus,” the biggest slug I had ever seen.  Hard to get a sense of scale in the photo, but notice the relative size of her rhinophores (normal sized rhinophores, dwarfed by a large body) and intense ruffling of her parapodia. Photographed at Andrea I, a nice dive site with relatively easy entry and exit.

Huge, ruffly E. crispata.  Bonaire

Huge, ruffly E. crispata. Bonaire

Also at Andrea I, another blue and green specimen, showing the characteristic large, white spots on the midsection.

Blue E. crispata.  Bonaire.

Blue E. crispata. Bonaire.

Here are a few other shots from among the hundreds.  They may not be slugs, but it is my site, so I can post what I like.

Common Octopus, Bonaire

Common Octopus, Bonaire

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Green turtle. Dozing on windward side of Bonaire.

Tang Parade!

Tang Parade!

 

Origin Myth, Part 1

Why does this page even exist?  It started with the guy in the picture below, a Humboldt squid (Dosidicus gigas).  More correctly, this story starts with the lack of them.

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In 2012, I was lucky enough to be volunteering as a Visiting Scientist with Ocean Discovery Institute during their annual research/education trips to Bahia de los Angeles in Baja California.  I had traveled to Bahia de los Angeles a few times with my friend and colleague Dr Drew Talley, and had spent about a week in the summer of 2011 with the Ocean Discovery Bahia Program as a Visiting Scientist.  They are an amazing group, and I always come back from visits with them feeling energized about science and education.  In 2012, I agreed to assemble a workshop on a subject in which neurobiology intersects marine biology.  In previous years, the large Humboldt squid had been relatively plentiful, so it seemed like a perfect opportunity to demonstrate for the students the electrical properties of the giant axon and the role it plays in the behavior of the squid.

After many, many hours of preparation, including purchasing a SpikerBox to serve as an amplifier, getting some help from the departmental shop in building a portable, battery-powered stimulator, talking with resident experts about recording giant axons, and trying to think of every contingency that might come up when trying to perform electrophysiology in a remote environment, I was ready to go. So, briefcase full of delicate gear in hand, I headed to San Diego and ultimately Bahia.

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It was a perfect plan.  I had thought of and coordinated everything, and we were ready to catch squid.  Drew and I went out with a couple of fishermen to drop jigs and pull up feisty cephalopods.  It was a gorgeous, warm, clear evening, and the water was as smooth as glass.  We stopped at a spot near the island Cabeza de Caballo, enjoyed a group of feeding pelicans and boobies, and learned how to use the jigs to catch squid.  No luck there, so we moved.  No luck.  We very much enjoyed the dolphins below us, illuminated by the bioluminescence, but then Drew asked the Question I Should Have Asked Myself Earlier: “What if there are no squid.”  Had not planned for that one, and yet there were no squid to be had.

I woke up the next morning with about 12 hours to assemble a workshop.  I was lucky that one of the student groups was not working that morning, so we all went out to search for squid substitutes and to discuss a little invertebrate zoology.  Nothing perfect, but among our collection was a pair of Elysia diomedea, about which I knew very little at the time.  So, by late morning, I had one cockroach (a Periplaneta that had been caught in a bathroom the night before), a SpikerBox, two slugs, and a video about cephalopod camouflage from the Hanlon Lab.

In the end, I used the materials I had to introduce the students to the field of Neuroethology, the evolutionary and comparative approach to animal behavior and neural circuitry.  The organization of the workshop may have been a bit rough, but the amazing scenes in the Hanlon video and my enthusiasm for neurobiology and behavior pulled us through.

All this got me thinking.  First, if I am so excited about neurobiology and behavior in a natural context, why am I studying the actions of drugs in a reduced system?  Second, as I learned more about the biology of Elysia diomedea, I started to think that there may be some really interesting neuroethology in there somewhere.

Given that I was on the cusp of a career change, these seemed to be issues to be considered in some depth.  Stay tuned.

Here are the original stars of the show, sitting on a counter in a plastic tub.  Possibly one of the dullest videos on YouTube.