We were lucky enough to spot some tarpons while inspecting a sunken barge at about 110 feet. Seeing them made me realize I know very little about these fish, spurring a bit of fun internet reading.

Tarpons are members of a group of fish known as elopomorphs that also include bonefishes and eels. One cool thing about elopomorphs is that all members of this group of fishes all have leptocephalus larvae, which look like really flat eels with glassy transparent bodies. If flat mini eels with see though bodies sounds delicious to you, eel leptocephalus (or elvers) are considered a delicacy in the basque region of spain.

The atlantic tarpon, Megalops atlanticus, cruising around near sunken wreckage at 100′. Although we only saw two, we were told a school of four are hanging around the wreck.

Prime tarpon habitat in Curaçao

A Leptocephalus larvae, the larval stage shared by tarpon, eels, and their relatives

Matt swimming towards a tarpon

A tarpon cruising along the sunken barge

The remains of the crane the barge was carrying

There are two species of tarpon, with only one (Megalops atlanticus) found in the atlantic and caribbean (that is the species you see in the pictures above).  They can grow up to 8 feet in length, though most tarpons average between 2 and 4 feet. I had always assumed that these were pelagic fishes that would rarely come near shore, but I was apparently wrong. Instead, tarpon live in brackish, fresh, and saltwater.  

Additionally, they have a bizarre swim bladder that functions as a respiratory organ. While this is not uncommon in fishes, tarpons are the only pelagic teleosts to use their swim bladder this way. In fact, if juveniles cannot come up to the surface to breathe, they will drown. Adult tarpons keep this air breathing function and use it to augment oxygen uptake during exercise, and this may also explain why tarpon can often be found in waters with a low oxygen content. In Curaçao, a school of four individuals are apparently long-term residents of the sunken barge.

As a side note, the barge was carrying a cargo of cars and a crane when it sank. Today, you can see this now decayed cargo strewn about the ocean floor.

Alex and Matt set out some rodent traps last night, and Alex and I went to check them this morning.  We didn’t actually find any rodents, but we did get a lot of pretty pictures of Cnemidophorus.  We also found a back road to a place called Watamula.  Watamula is said to be the best dive on Curacao, but it’s really only easily accessible by boat.

Alex checks a Sherman trap.

No visitors, so we fold it up and move on.

Alex is baiting his traps with balls of peanut butter and bird seed.

Lifting a pallet.

Cnemidophorus, posing.

And from the other side.

Posing with a pen Matt lost in this spot the previous day.

Check out my coool neck articulation!

And posing again.

Mammal count stands at zero, but the crab count has just gone up by one.

Just hangin’ around.

What’s this?

Oh.

A microteid. Crazy hard to catch, since they basically swim in leaf litter.

Big boulder at Watamula painted with the Curacao flag.

Rufous collared sparrow at Watamula.

The rock at Watamula has been carved into amazing shapes by the waves, and the water actually comes up under the land through tiny channels.

Or in this case, effin’ HUGE holes in the ground.

Although dramatic in its own right, Watamula is like a more mellow Shete Boca. We’ll post pics from Shete Boca soon.

Watamula. Not the most hospitable place.

Adult Cnemidophorus showing off his pretty tail.

Just keeping an eye out.

The lifting of pallets is a sacred ritual for herpetologists, as pallets are the natural habitat of many lizard species.  It is widely believed that T Rex routinely relaxed under the megapallets of the late Cretaceous.  Widely believed by me, anyway.

Here’s a set of pictures from days three and four.  Teresa and I were mainly busy trying out some methods for collecting behavioral data, but I did manage to snap a few pictures.  Some are from Playa Jeremi, others from Playa Lagun.

This little guy was in the tree outside when I woke up.

Dammit, Mio, that’s CITES listed!

The proverbial fish in a barrel.

What’s goin’ on in this sponge?

Blue coronetfish. I’ve been diving in Curacao many times, and never used to see these guys. They seem to be fairly common this year.

On this dive we actually saw a PAIR of coronetfish. Awwwww.

Goldspotted eel, Myrichtys ocellatus.

We saw this little guy on the way out. Lovely habitat.

The bluespotted coronetfish are particularly cool to see in action.  They move like some weird hybrid of a fish and a squid – a fid, maybe, or perhaps a squish.  The largest one in these pictures was about five and a half feet long.  According to our field guide, that’s quite large for this species.

As for the actual science going on in these dives, we’re basically just trying to figure out the best way to measure territoriality and sperm competition in the blueheads.  We’ve tried a bunch of ideas at this point, and we’re planning to have a sit-down with Peter Wainwright when he gets here to discuss which method we’re going to pursue for the rest of the trip.

Here on Curaçao, we unfortunately encounter quite a few roadkilled iguanas (Iguana iguana).  That this species is listed as CITES II makes this especially tragic, so the least I could do is preserve it for Science.  Therefore, if I run across a specimen in reasonably good shape (i.e., not a pile of lizard goo), I collect it, take DNA, and preserve it for a museum.  The problem is that these specimens may be sitting out in the road for a few hours and can become rather… ripe.  In this case, they don’t preserve well in formaldehyde so I prep them for skeletonization.  To do this, I have to remove the skin, organs, and as much meat as possible.   During this process, I take a tissue sample for DNA.  After that, I dry out the carcass into lizard jerky as quickly as possible so flies, birds, and other interested parties don’t eat it.  Eventually, we’ll take it back to the U.S. (with CITES documentation, of course) and give it to dermestid beetles that eat the rest of the meat leaving a nice, clean skeleton.

If any thrash metal bands are reading this, I suggest “Prepped for Skeletonization” for your next album title (cover art below).

Here, I’m injecting formaldehyde into the tail

Filling the body cavity with formaldehyde

Drying out the Iguana specimen. Once it is lizard jerky, we can package it and take it back with us to the U.S.

Dermestid beetles cleaning a skull (http://www.wattsskulls.com/images/frenzy.jpg)

Part of the point of this blog is to document the process of doing science.  When it comes to doing field science, that often means trying to figure out some clever hack that will allow you to trick an animal into telling you about itself.  One of the things we really want to be able to find out about bluehead wrasses in the study we’re currently working on is the level of territoriality different individuals display.  Here’s one attempt we made at collecting this data.  It involves a device we’re calling the Angryometer.

Here’s the mostly-assembled angryometer on dry land. It consists of a microphone stand with a weighted base, an adapter to convert the mic stand to a camera tripod, and a waterproof GoPro Hero camera. The Hero is designed for extreme sports. It has a wide angle lens, is waterproof to 100 ft, and best of all is dirt cheap. The entire apparatus shown here cost about $140 to assemble. Although the present application involves pointing the Hero down at a mirror to film fish aggression, this same setup (sans mirror) could be used in any application where you want a stationary camera underwater in low to moderate current.

Taking the angryometer out for its first real trial at Playa Lagun.

This looks like a tiny version of the famous rock islands of Palau. Neato!

Nice place.

The angryometer underwater with mirror attached. Our original mirror was broken in transit, as frequently happens with anything even slightly fragile that goes through MIA. We just bought a cheapo bathroom mirror in Willemstad and glued it to a cutting board for strength.

Angryometer with potential customer. The little blue and green guy that you can just barely make out is one of the males we’re trying to piss off. This one didn’t do much, but we did finally manage to catch somebody’s attention.

Did it work?  Well, sorta.  We did get a terminal phase bluehead interested in it, and after a few trial passes he finally went mano a mano (or perhaps fin-o a fin-o) with the mirror until we took it away.  It’s exactly the sort of data we wanted from the apparatus, but we’re probably not going to be able to use it anyway; it takes too long to get the fish to make the initial approach, so we probably wouldn’t be able to get enough individuals responding to get the sample size we need.  It was still pretty fun to see how the different species responded to the mirror, though, and perhaps we’ll play some more with this later.

I’ll try to remember to post some of the video once we get back to the States.  The internet access here is a bit sketchy, so anything that large is difficult to upload.

Most of the contributors to this blog are now in Curacao, and we’re trying to post some field notes and content.  The internet access here is a bit like a slot machine, though; you push the button and cross your fingers that you didn’t just throw away everything you put in.

It’s interesting to see how the sensitivity to catnip is clearly polymorphic within species and yet conserved over evolutionary time scales OH WHO AM I KIDDING KITTIES!

The purpose of this blog is to chronicle the day-to-day of a few young scientists.  The format is informal, and the content will range far and wide.