A very venomous field season: Welcome to Okinawa

by Andrew Wood, a University of Michigan graduate student in ecology and evolutionary biology

This, my first post to EEBlog, comes almost exactly two weeks after leaving Ann Arbor, and nearly a week and half after arriving here at Sesoko Station in Japan.  I have come here along with just-graduated and eminently talented Alyssa Lawler to collect marine snails in the genus Conus – known commonly as cone snails.  The genus is an oft-cited exemplar of adaptive radiation, and is among the most diverse groups of extant marine animals. Those unmoved by the biological panoply of cone snails are often drawn by the spectacle of their shells, which are always beautiful, often intricate, and sometimes positively grandiose.  Any ears that remain apathetic usually perk up (if only from an instinct of self-preservation) upon hearing that cone snails are venomous, some species packing venom potent enough to paralyze adult Homo sapiens in a matter of seconds.

Conus geographus.  This individual was collected on June 16th and passed along to us by Shawn Miller, an incredibly helpful and knowledgeable man who has been giving us lots of advice on Conus collections.  This is the most dangerous cone snail, and is responsible for the greatest number of human fatalities.  It is also much sought after for its beautiful shell.  Photo courtesy of Shawn Miller.

While I find pretty much all aspects of Conus biology fascinating, this last fact is what keeps my interest for the long haul.  That is because their venom is intimately wedded to their ecology, and is likely a critical explanatory factor in their stunning diversification.  What researchers have gathered from some species of Conus suggests that they are very picky eaters, and that their tastes do not overlap much with other species – that is to say that their diets are fairly specific, and represent the major axis of niche differentiation.  Because cones use their venom primarily for prey capture, this suggests that their venom may be adapted to a fairly specific range of prey items.  Indeed, a common explanation for the diversity of Conus is that their venom evolves to function specifically on different prey assemblages, thereby erecting post-zygotic barriers to gene flow.  There is substantial evidence that venom does indeed evolve in response to novel prey assemblages, but a key part of the puzzle is missing: no one has ever demonstrated that a cone snail’s venom actually works better on it’s own prey (intra-dietary) than it does on the prey preferred by a different species of cone (extra-dietary).  Ultimately, it is my goal to fill that knowledge gap. I begin that effort this summer, here at Sesoko Station. My plan is to characterize the diets of several species of fish-eating Conus.  When I complete this task, I can come back next summer, collect the fish that they eat, and assay the effectiveness of venom on intra-dietary and extra-dietary prey.  That’s the plan anyways, and I will keep this blog up to date with what we have accomplished thus far.
X marks the spot.

Sesoko Station is run by the University of the Ryukyus and is the premier marine biology field station in Japan.  It is situated on the small, vaguely T-bone steak shaped island of Sesoko, just off the Nago peninsula of the island of Okinawa – a name that should be familiar if you paid even the slightest attention during history class. The invasion of Okinawa by the United States Marine Corps was the last major land battle fought in the Pacific theater during World War Two, and was signally bloody and brutal in a war that was bloodier and more brutal than any waged before or since.  The battle for Okinawa was so bad for both sides that it is often cited as a significant factor in Harry Truman’s decision to use the atomic bombs on Hiroshima and Nagasaki, lest the struggle for the Home Islands of Japan prove as ruthless.

Posted warning of unexploded ordinance.

Last Thursday, a grim reminder of this history surfaced when an unexploded bomb was found buried in the sand out in front of the station.  Absent occasional reminders such as these, however, you would never guess that there had ever been enmity between the peoples of Japan and the United States. Minnesota – my home state – is famous for “Minnesota Nice”, a term referencing the storied friendliness of its inhabitants.  Natives will tell you that in reality though, this friendliness simply reflects an impressive degree of passive aggressiveness on the part of all the cantankerous Scandinavians who lack the requisite social skills to let you know directly that they’re not interested in what you have to say.  Such does not seem to be the case here.  Everyone is exceedingly kind, generous, and, important to me and my abysmal Japanese skills, patient.  Quite a lovely place.

The University of Michigan has a history of collaboration on the island of Okinawa, and at Sesoko Station specifically.  Current PhD candidate Alison Gould has spent several field seasons here, and her advisor, Dr. Paul Dunlap is a perennial presence, either here at Sesoko Station, or at the Okinawa Institute of Science and Technology, where he can be found presently.  We are among 20 or so people currently using the station’s facilities.  It is a smattering of faculty and students, Japanese and foreigners alike. My roommate is an Austrian named Wolfgang (not a composer) who likes to argue about the relative historical greatness of European imperial dynasties.  I was grateful upon our introduction when his first words to me were, “I hope you like it cold.” Our thermostat is kept as low as it will go to combat the oppressive heat and humidity.  As you can see below this is a truly beautiful place, and I am very lucky to be spending a month and a half here.

Sunset near Sesoko.  Photo courtesy of Alyssa Lawler.

This past evening Alyssa and I collected cones at night for the first time.  We have been out a lot in the last week and a half, visiting various reefs and beaches, collecting animals, and making notes of promising habitat. The species that we are targeting most keenly, however, are fish-eating Conus, which are active mostly at night. I may be a bit of a sissy when it comes to these things, but the novelty of our surroundings, combined with warnings about the menagerie of dangerous and/or poisonous animals in the waters surrounding Okinawa makes me a bit nervous about getting into the sea at night with only a small cone of illumination ahead of me.  To be sure, the odds that we will tangle with any of these animals are extremely low (a somewhat distressing fact, since our target species of Conus are among those dangerous animals listed), but it’s certainly fodder for the imagination.  Ever heard of needle fish?  They can grow to several feet in length, and have a spear on their face.  Apparently when they see a light on the surface of the water, it triggers a fixed action pattern whereupon they jump madly through the water until reaching (and impaling?) the light source.  The preferred (and hilarious) method for catching needle fish is to strap some lights to a big ball of Styrofoam and drop it in the ocean, the idea being that any nearby fish will make a beeline for the ball, sticking into it and quivering like an arrow on a bulls-eye until they are plucked off by the fisher-person. We were warned to point our dive lights down when collecting at night.

The view when snorkeling on the reef at night.  We saw a stone fish, scorpion fish, all manner of strange mollusc, and lots of Conus!  Photo courtesy of Alyssa Lawler.

As we have not been out at night very much yet, we have only collected three fish-eating cones so far.  We have collected about 100 individuals representing around 12, mostly worm-eating species, however.  This is good, for a couple of reasons. First, I need worm-eaters for another project that I have planned that deals with the olfactory prowess of Conus (more on that another day).  Second, it has given us good practice in organizing samples and caring for the animals (what kind of containers work best, etc), and most critically, it has given us lots of practice dissecting them.  I will keep this blog up to date with progress towards my goal, as well as installments with more details about our collections, lab setup, and perhaps a tutorial on how to dissect a cone snail.

Thanks to Gail Kuhnlein for inviting me to participate on the EEBlog!