Exploration at La Selva Biological Station

I recently had the amazing opportunity to visit La Selva Biological Station, operated by the Organization for Tropical Studies, on a class trip. The station was established in 1971, and is one of the most important biological stations for tropical rain forest research in the world: every year 250 scientific papers are published from research done at the station. Pretty impressive for a station only 15 square kilometers in area. It's operated by a consortium of 63 universities, and they do a great job of managing it.

Unfortunately, due to the massive amount of pictures I took while there, I can only select a few to elaborate on, so I'll make those count. Let it be said, however, that there are a massive amount of interactions, plants, animals, and so many other organisms at the station, and in the rain forest as a whole. It's no wonder that so much research comes out of the place.

 Bridge over Río Puerto Viejo, containing crocodiles and fruit-eating piranha.

I had a lot of time to explore (yet, not enough), so I took full advantage of that. I found a lot of birds: hummingbirds, toucans, huge birds that reminded me of turkeys, and others that reminded me of a raptor from Jurassic Park. I have yet to identify them, but I'm pretty sure they weren't dinosaurs. (Unless you agree with the people who think that birds are in fact dinosaurs, according to systematics. And I do. So more accurately, they weren't scaly dinosaurs that I would have to worry about hiding in tall grass.) One of my favorite birds I saw was a Cherrie's Tanager (Ramphocelus costaricensis). When resting on a branch, it looks like a black bird with pretty red feathers near its tail, but when it takes flight, it's an unexpected explosion of red and quite beautiful.

Of course, Biology isn't all about birds. Almost everywhere you looked, there were epiphytes on the trees. Epiphytes are simply plants which grow on top of other plants. Mosses and lichens? Sure. (Lichens aren't technically plants, but you get the idea. Something growing on something else.) In the rain forest, you get even more variety with epiphytes. Many species of bromeliads (some more than six feet across, depending on how large the tree is) and orchids are epiphytes, and they were abundant. Bromeliads have a central tank in which water is stored, and these tanks are ecosystems in their own right. While at La Selva, I found katydids, mosquito larvae, spiders (More like Shelob than Charlotte. Seriously, that thing erupted from a small bromeliad and was a monster--as big as my palm.), and more hanging out in the tanks. Some species of frogs even use them as nurseries for their young. The eighth episode of Planet Earth, "Jungles," shows the relationship between species living in a pitcher plant, and it's the same concept, very neat.
 

That's a lot of bromeliads.

One of the most exciting things I found in La Selva was also one of the smallest. It's also an example of why you need to take the time to slow down and examine the things around you, rather than running around only looking for the big organisms. Upon looking at the underside of a leaf (I believe it was a species of Heliconia), I found a small ant. It wasn't a normal ant, however. It was stuck to the leaf, obviously dead, and had something growing out of its head. Looking closely, I was astonished to find that it was a fungus! Its fruiting body, a small mushroom, was growing out of its head, and another stalk was growing from its abdomen. 

It was one of the most exciting things I've ever seen. And thanks to Planet Earth, I knew what it was. Also in the "Jungles" episode, Sir David Attenborough talks about a particular type of fungus, of the genus Cordyceps. This fungus is an endoparasite (a parasite that lives inside of another organism), and it has a unique way of carrying out its life cycle. It infects a host, then sends out its mycelia (think of those as the roots of the fungus), which eventually replace the host's own tissue. Some species are able to change the host's behavior (zombie ants!), causing it to climb to a high leaf or branch and attach itself there. After the host has died, the fruiting body of the fungus (its stalk and mushroom) grows from the dead host and releases its spores, which land in different places around the forest, waiting for the next unfortunate host to step on them and get infected, to continue the circle of life. If that's not beautiful, then I don't know what is. Parasitism at its finest. Though really, it's more like parasitoidism.

Note: While I'm not entirely sure that the fungus is in the genus Cordyceps, it's the assumption I will go by until I find conflicting information. Disclaimer: I could be entirely wrong on the identification, but the process of fungal infection is most likely the same.

The segment of Planet Earth with the Cordyceps interaction can be viewed below:

Venturing forth across the bridge, I found even more. Spiders of many sizes and colors (with some neat webs), moths, a cockroach, katydids, fungi (just taking part in detrivory, not parasitoidism this time), metallic flies, many mating millipedes (actually, almost every millipede I saw was mating...), and a peccary (think wild pig). In addition to this, I had an encounter with a poison-dart frog. In this case, the blue jeans morph of the strawberry poison-dart frog (Oophaga pumilio). This one is the most toxic species in its genus, but isn't the most poisonous of the poison-dart frogs. Still, I didn't touch it. It probably wouldn't have appreciated it anyway.

I assume you now realize why it's called the blue jeans morph.

This trip being part of a Tropical Ecology class, I had a hike with a guide next, which was pretty sweet. Slight interjection: the food at La Selva is top notch. It is not a Biological Station where you will go hungry or dislike the food. Delicious. Anyway, we hiked into the forest. Starting off, we saw some spider monkeys (genus Ateles) and heard howler monkeys bellowing (oddly enough, they sound like a large dog. Except this dog is hanging out high up in the tree canopy.) La Selva has three species of monkeys, so two out of three before we had really started our hike wasn't too shabby. Howler monkeys are pretty interesting, and they lead tough lives from birth. Female howlers will attempt to kill young howler monkeys of other females in order to increase their own offspring's success. How.....sweet. Howler monkeys live in troupes, and in La Selva usually band together in groups of about 15 or so individuals, which have an alpha male. That alpha male will sometimes attempt to kill the offspring of the females, so that he can mate with the females again. Priorities, I suppose. Add to that the fact that howler monkeys usually have only one or two offspring, and it's a bit of a hard life for baby howler monkeys. 

The most interesting thing we found on our hike was a small group of Honduran white bats, Ectophylla alba, huddling together in a tent made from a Heliconia leaf. They're tent-making bats, one of 15 species in Latin America. They do it by cutting the side veins of the Heliconia leaf to the mid vein, which causes the sides of the leaf to fold over, creating a tent. Being small, the little white marshmallows huddle together for warmth and can be in groups of a dozen. In the little group we found, there were three. Usually the groups consist of one male, with a harem of females. Make of that what you wish. 

For some clearer pictures of the bats, check out The Featured Creature.

With some extra time between dinner and our planned night hike, I explored some more. As mentioned earlier, I found a huge wolf spider. While the picture doesn't have much to show for scale, look at your hand, and imagine a spider as big as your palm. That's the approximate size. Fortunately, I found a friendly enough lizard after the spider, which wasn't nearly as creepy.

Shelob.

Much less creepy than Shelob.

And then came the night hike. Sitting on the porch of my cabin around dusk, I noticed a remarkable change in the makeup of the forest wildlife. It was a quick, but seamless transition into the chorus of katydids taking over for the night and producing much of the noise in the forest. It sneaks up on you inconspicuously. Then you realize that there has been an almost imperceptible change. Pretty neat. Once the night sets in, the fireflies start turning on their bioluminescence. You can turn off your flashlight and just watch the trees light up with males attempting to attract females. It's a dazzling mating ritual.

These guys are tricky.

During the night hike, we finally found some snakes. I was excited, but kept my distance. I respect snakes, but would rather leave them to be investigated by the herpetologists. All the snakes we found were in the trees, hunting for their meals, and were relatively small. No fer-de-lances or anacondas. I'll spare you the blurry pictures: I'm sure Google and Flickr have better ones than I do. Still, they were pretty neat. Great camouflage on them, they're tough to spot even from a few feet away. The fauna at night was quite different, and more diverse than what I had found during my day explorations. More frogs were out, especially the tree frogs, and I found a camel cricket, stick insect, scarab beetle, many moths, and some Hemipterans. We even saw an armadillo come lumbering across the path. Looking back at the pictures, I can't help but notice some similarities between some bugs I found at La Selva and some I've found back in Ohio.

I couldn't leave this picture out. This guy was found near our cabin.

Unfortunately, my second and last day at La Selva arrived all too quickly. A 6:30 AM wake up time was a bit daunting, but necessarily. Following the advice of some other men who were staying at the station, some friends and I took some pieces of banana over to the bridge after breakfast, and dropped them into the river. A few seconds later, the waters were churning (and continued to churn after we kept throwing in more pieces): there were frugivorous piranha in the river. 

The assignment for the day was to go into the forest and find a relationship between two organisms. While quite simple, I was enamored with the thought of having four hours to explore the rain forest. So off my partner and I went! 

Check out those mandibles.

 As you can tell, the exploration started off very well. That's a longhorn beetle, and its antennae were indeed quite long. The beetle itself was at least three inches long.

We eventually reached a meadow of sorts, and found a termite nest at least three feet in height and about two in width, six feet up a tree. It had trails crossing all over the tree, and was doing a number on it: the tree was slowly being hollowed out. Even more interesting is that the termites themselves have a mutualism with protozoa in their guts: the protozoa digest the cellulose from the wood for the termites. On top of that, the protozoa have mutualistic bacteria inside them that help to produce enzymes to help break down the cellulose. Ecology: just when you think you have a clear-cut relationship, more and more get piled on.

While not as terrifying as a wasp nest, still not something to mess with. 

Then we saw the bullet ant nest. And by saw, I mean to say we walked through a line of bullet ants without realizing it at first. Not necessarily the best thing to do, but the bullet ants didn't seem to mind. I laid my pencil on the ground for scale while I was taking pictures of the ants, and one go-getter decided to attack the pencil. It bit the top, wrapped its legs around it, and attempted to sting it quite vigorously. If that had been my finger instead of the pencil, I would have been in some intense pain. As in, enough pain that I wouldn't be able to do much with that finger for a few days. Or possibly hand and arm, for that matter. Yeah, don't get bitten by bullet ants.

I wonder which hurts more: the bite from a bullet ant, or the bite from a wheel bug.

After passing by another line of bullet ants (one ant had an unfortunate caterpillar in its jaws), we came upon a small gazebo and sat down for a while, gathering our thoughts, watching the activity around us, and listening to the sounds emanating from the forest. We saw a coati (related to the raccoon) digging around and then sunning itself (it looked very zen), heard the calls of howler monkeys, the grunts of peccaries, and the droning of cicadas. 

A coati: the elongated raccoon of the forest.

Leaving the gazebo and heading back to the station, we saw the aforementioned raptor bird, some gigantic trees, and more interesting insects. We saw an agouti, and while I was busy taking a picture of a leaf-footed bug, I heard a scream. Apparently a bullet ant had hitched a ride on my partner, and she noticed it crawling over her knuckles while she was waiting on me to get my picture of the bug. Thankfully, she shook it off quickly. Dodged that bullet.

Yes, that is a very tall tree.

If there were raptors at La Selva, they would be hiding in there.

  

After that excitement, we continued on our way. The last thing of note we found were some mantis oothecae (egg sacs), both at least two inches in length. Now, a Chinese mantis, which is about three inches long, lays an ootheca about the size of a ping pong ball. I would have loved to see the mantis that laid these ones, it would have been quite large.

After buying some identification guides for beetles, it was time to head back. La Selva is a great place to find all kinds of wildlife and interactions, and it was a great opportunity to be able to visit. You could easily spend months (or more) there and never get bored. 

Sadly, I can't post all the pictures I would like to from my trip, but here's a small summary of what else I saw while I was at La Selva:

-Ctenosaurs/Iguanas? hanging out in the tree limbs above the river
-Very sharp (tested myself) thorns erupting in bands from a tree stem. Did not stop the epiphytes from growing on the smooth space in between the bands of thorns, however.
-Katydids, beetles, moths, frogs, wolf spiders, turkey bird...
-Tree growing halfway up a dead one: it needed that sunlight!
-A flower high in the canopy dropping long threads of who knows what. Think white spaghetti noodles.
-Nine harvestmen (Opiliones, AKA Daddy-long-legs) on one leaf.