Anaconda Expert Wades Barefoot in Venezuela's Swamps

Hillary Mayell
National Geographic News
Updated March 13, 2003

This story airs in the United States tonight on the National Geographic Channel's Five Days of Snakes—a series of programs about serpents, and the scientists and others who work with them.

Jesús Rivas has the kind of job that would keep most of us lying awake at night hoping to keep the nightmares at bay. He's a man who has followed his passion, and his passion is giant snakes.

The green anaconda to be specific, the largest snake in the world.

Other snakes may grow longer, but none matches the length and weight of the anaconda. The largest specimens can grow to close to 30 feet (9 meters) long and weigh 1,200 pounds (550 kilograms).

Rivas, who grew up in Venezuela and is now a visiting scholar at the University of Tennessee, thinks science should be conducted the old-fashioned way—out in the field.

To find the snakes, he wades—barefoot—in the knee-deep water of the Venezuelan llanos, the lowland savannah that is flooded each year during rainy season.

"The anaconda is the master of the swamp," says Rivas. "Before 1992, no one knew anything about it, and you can't really know anything about an animal by building computer models in the lab. You have to put on the shoes of the snake and wear them. That way you learn the difference between the truth and what you think the truth is."

Rivas started the Anaconda Project in 1992. For ten years, Rivas and a revolving group of graduate students and volunteers have captured and released about 800 green anacondas. As a result, some of the giant snake's story can now be told.

Amid the Llanos

The llanos is an ecosystem of extremes. About 5 feet (1.6 meters) of rain falls each year, flooding the lowlands during the wet season. Yet during the dry season, from January to April, the land is so parched it more closely resembles a desert, with temperatures soaring up to 130 degrees Fahrenheit (54 degrees Celsius).

"Great for birds, horrible for fish," says Rivas.

Animals such as the green anaconda that depend on water must seek safe havens to survive. They generally retreat to mud holes and cool, damp caves.

The primeval landscape where Rivas and his colleagues work is home to animals not seen in more temperate arenas—capybaras (giant rodents that can weigh up to 140 pounds [64 kilograms]), giant and lesser anteaters, crab-eating foxes, armadillos, raccoons, giant river otters, spectacled caimans, side-neck turtles, green iguanas, and tegu lizards.

Continued on Next Page >>


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