At the El Frío Biological Station, graduate student and herpetologist Kate Jackson helps heft an anaconda.

Andean Classroom

Biology 250 meets in Venezuela.

Photographs by Geoff Morse

Juan Silva had warned us about the killer bees. Silva, a visiting professor at Harvard last fall, had called the bees by their more proper name, "Africanized honeybees." But his warning had signaled all the danger implicit in the ominous nickname. We knew the standard advice: watch for hives and don't go near them. If the bees attack, run away as fast as you can or perhaps jump into water.

Now, an Africanized honeybee swarm shot toward the group of Harvard students across the puddled yet dusty landscape of tropical savanna south of the Apure River in Venezuela. The bees spun like a biological tornado and sounded like the whining tires on a Mack truck. There was no time to run, and the pools of water around us were laden with crocodiles and anacondas. We simply froze.

The strange cloud moved through us and flew on. It was over in an instant, another of those events that happen in the tropics far too quickly for anyone to panic. For a few moments, we sorted out together what had just happened to us, achieved the intellectual equivalent of a group "Wow," and went back to studying the eyes of the crocodiles in the muddy water just beyond our feet.

Coffee caterpillar. Its coloration warns predators of painful spines.

Dragonfly eating a native bee.

The "backwards beetle," a weevil, uses its snout as an ovipositor.

Longhorn beetle. Larvae burrow in and eat wood. Adults eat pollen.

Welcome to another day of the (optional) three-week field trip of Biology 250, "Tropical Ecology." The one-semester course is offered every other fall, and each odd-year January, about 20 Harvard students venture to the Venezuelan Andes and environs to reinforce lessons learned about ecological patterns and processes during lectures held in the University Herbarium. They do so aware that the tropics contain some of the world's most diverse biological communities, which have long been sources of scientific insight. At the same time, the students are aware that ecological destruction is disrupting these communities at a rapid rate.

On the trip, as waves of gastrointestinal distress captured many of us, the group explored nearly two dozen tropical habitats, from hot, humid lowland rain forest to the snow-line region in the high Andes. Along the way we were briefed and guided by Silva and other faculty members of the Universidad de los Andes, in Mérida, a city among the heights situated, literally, in the shadow of Venezuela's tallest mountain, Pico Bolívar, at 16,430 feet.

As a Knight Science Journalism Fellow at MIT, I tagged along with the students, lecturer Mark Leighton (standing in for Bullard professor of forestry Peter Ashton, who was on sabbatical), and teaching fellow Christopher Dick, pursuing, in my mid forties, a lifelong passion for learning about nature in general and tropical ecosystems in particular.

The trip brought new insights for all of us, spurred on, to use the words of the great explorer-scientist Alexander von Humboldt, "by an uncertain longing for what is distant and unknown."

Experiments comprised much of the intellectual content of the field course, as students gained experience conducting short-term scientific investigations. They each formulated a hypothesis, planned methods to test it, produced results from fieldwork, and wrote complete scientific papers, including detailed statistical analyses of their results.

That was why several days earlier I watched mosquito after mosquito land on my forearm, dip its proboscis into my skin, and start spitting into my blood supply. It was part of an experiment designed by Rania Milleron, and one of many conducted over the next three weeks by the students. Milleron, a graduate student, had devised a system to survey mosquito populations on the mountain. The aim of the experiment was to find out if the number and abundance of mosquito species varied at different altitudes, and, thus, different climate conditions.

We broke into two two-person teams: Milleron and graduate student Sandra Andaluz, and Yukiko Otsuka, also a graduate student, and me. As I stood like a scarecrow and watched mosquitoes home in on my exposed skin, Otsuka sucked them through a rubber tube connected to a glass pipette. She then blew each captured bug into a collecting tube laced with insecticide. After a few minutes, we switched roles, and within a few hours, we collected dozens this way. (Humboldt, had he known the relationship between mosquitoes and disease, would have been shocked at our bravado, especially since he suffered a bout of Venezuelan malaria. We put our faith in mefloquine.) The data-- and more collected the next day-- supported Milleron's hypothesis that higher up, the cooler conditions translate into less mosquito activity and diversity.

Geoff Morse, a graduate student of entomology, at 12,000 feet in the Sierra Nevada National Park. Kate Jackson Birder Chris Witt, a senior in Harvard's visiting undergraduate program, by a daisy tree in the cloud forest.

Humboldt, whose writings inspired Darwin, Lyell, and other great scientists, traveled through Venezuela in 1800 as part of his five-year journey through Spain's American colonies. He never had to face any Africanized honeybees, but then our trip held nothing like the level of danger from disease, violence, and accident that Humboldt endured. Although powered by jet, bus, and outboard motor rather than sail, foot, and mule, the Harvard group journeyed in the same spirit of land-based scientific expedition, very much the intellectual offspring of Humboldt and other scientist-naturalists who explored the New World tropics in centuries past.

At the end of our time in Venezuela, near the El Frío Biological Station, we stopped for half an hour on a bridge over the Apure, not far from where Humboldt had passed. A few of us peered through binoculars at the water to the west, scanning for the pale-colored river dolphins that Humboldt had described as "noisy and impetuous" as they "play in long lines on the river surface." Within a few minutes, we spotted a group of three. This was no long line, and they were hardly playful. A somber juxtaposition--those two images of the dolphins--symbolizing, perhaps, two centuries of ecological change.

~ William Allen