Joe Elbert's Zoo Tales
Smooth-sided toads and silver-beaked tanagers breed freely; titi monkeys jump from branch to branch; a two-toed sloth hides behind large leaves; and sun bitterns stalk small fish at the water's edge. This is a mere drop in the tropical bucket that makes up the National Zoo's Amazonia exhibit.
The exhibit mirrors the wild habitat of the Amazon River, which stretches more than 4,000 miles, and its tropical rain forest, which is home to millions of plant and animal species. It is, in fact, the most biologically diverse ecosystem on Earth. In many zoo exhibits, the fauna overshadows the flora, but in Amazonia the plants take center stage. Within Amazonia's conservatory is a tropical forest with more than 350 species of plants, including 50-foot-tall trees, vines and epiphytes.
This habitat also houses dozens of species of mammals, birds, reptiles, amphibians and insects typical of the Amazon basin, all moving throughout the exhibit.
The 15,000-square-foot rain-forest habitat features a tropical river and a 55,000-gallon aquarium teeming with a variety of Amazon River fish. The Amazon has the greatest fish diversity of any river system on Earth, as well as some of the largest freshwater fish in the world. You can come face to face with several of these giants, including a seven-foot-long arapaima, in Amazonia's giant-river-fish exhibit. The arapaima is one of the largest freshwater fish in the world and the biggest fish at the National Zoo. Arapaima can grow to lengths of up to eight feet. Visitors can marvel at these giants during feeding demos at 11 a.m. on Fridays, Saturdays and Sundays. Amazonia's flooded forest exhibit is home to freshwater stingrays and giant river turtles. Stingrays eat crabs, mollusks and other small invertebrates that they forage from stream and river sediments. Amazonia's giant river turtles, some of which can weigh up to 200 pounds, are primarily herbivores and prefer the soft parts of aquatic plants.
Other notable creatures you'll find in Amazonia include poison-dart frogs, so named because some Amerindian tribes have coated their darts with the frogs' toxic secretions.
The most deadly species is the golden poison arrow frog, whose poison, batrachotoxin, is so potent that the amount from one frog can kill many humans. Arrow frogs are not poisonous in zoos. Scientists have found that wild frogs obtain the poison from their diet of insects and other arthropods, which most likely acquired the poison by eating toxic plants. Piranhas also have a ferocious reputation. Their name, coming from their sharp triangular teeth, derives from the Portuguese "piro" for "fish" and sainha for "tooth."
Piranhas have long been thought to eat humans, but reports of man-eating fish are exaggerated. Most of the more than 20 species of piranhas in the Amazon are omnivorous, eating seeds, other fishes and the occasional animal that strays into the water.