Orinoco



Silver arowana, Osteoglossum bicirrhosum

Though the Silver and Black arowanas of South America, and the Asian and Australian arowanas resemble each other, and share the behavior of brooding their eggs and fry in their mouths, they last shared a common ancestor around 170 million years ago, when the great Southern Continent Gondwana began to split apart. This took place in the Jurassic period, when dinosaurs still thrived. Although Asian arowanas are endangered, South American ones are abundant, and are important both to subsistence fishing and the sustainable aquarium trade.

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Red-bellied piranha, Pygocentrus nattereri

It appears there are no documented cases of piranhas killing people, but there have been several cases where they have eaten humans that had drowned. In general, these specialized relatives of the tetras are opportunistic scavengers. Of the 50 or so species found in South American Rivers, this one is the most familiar, and is popular in aquariums for its bright colors. If maintained in groups of less than four, piranhas are likely to eventually kill each other. They have been bred many times in captivity.

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Cuvier’s dwarf caiman, Paleosuchus palpebrosus

Rarely longer than five feet, this widespread South American alligator relative is the smallest species of living crocodilians. In contrast to most other crocodilians, it prefers fast moving streams with relatively cool water. Rare in collections before the 1980s, it is now bred in captivity.

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Goliath bird-eating spider, Theraphosa blondi

Until 2001, when the Giant huntsman spider was discovered in Laos, this enormous tarantula of the Northern South American rainforests was known as the largest spider in the world, and is still the heaviest. The legs may span one foot and they can weigh up to six ounces. While it is certainly capable of eating small birds, their more usual prey is insects, frogs, and lizards. Their venom is comparable to that of a wasp, but they are also capable of damaging human skin with their detachable irritating hairs. Females can live to be 25 years old and males only to six.

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Striped basilisk, Basiliscus vittatus

Named for a mythical crowned serpent, basilisks are specialized iguana relatives from Central and South America. They are capable of running on their hind legs so quickly that they can cross water without sinking. The ornate crest on the head is actually an extension of the skull. This species is found from Belize to Colombia, and is also now one of the many reptiles that have become feral in Florida.

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Vampire bat, Desmodus rotundus

It might seem surprising that Vampire bats have the fewest number of teeth of any bat — only 20, most of them tiny. However the incisors and canines, that dominate their jaws, are superbly suited to slice through skin, giving their owner access to the blood that is its sole food. Found from Northern Mexico to Chile, they prey on a wide variety of sleeping mammals and birds, including occasional humans (who are often attacked through their toes). They do well in captivity, and most zoo specimens are captive-bred. Their DWA diet is cow’s blood.

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Blue poison dart frog, Dendrobates azureus

When these amazing frogs first appeared in zoos in the 1970s, they created a sensation and remained very rare in collections until the mid-1980s. They are now widespread in captivity, thanks to their popularity. As with other poison dart frogs, captive-bred animals raised on fruit flies and crickets lose their toxic qualities. Found only on a few “islands” of forest, arising out of the Sipaliwini savannah of Suriname and Brazil, they are considered vulnerable to extinction, so that their status as a self-sustaining captive population is especially satisfying.

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Budgett’s frog, Lepdibatrachus laevis

Named after J. S. Budgett, who studied lungfish, bichers, and amhibians in South America and Africa over a hundred years ago, this unique frog could be said to resemble a cross between a hippopotamus and a potato. Even the tadpoles have enormous mouths and are cannibals, making their propagation difficult for amphibian keepers. They do not have teeth, but can inflict painful bites with sharp-edged structures in the jaws. Found in Paraguay, Argentina, and Bolivia, these relatives of the horned frogs were very rare in captivity before the 1980s.

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Black-banded leporinus, Leporinus fasciatus

Growing to a foot in length, this eye-catching relative of tetras and piranhas is a typical inhabitant on flooded forests in South America. For more than 50 years it has been very popular in the pet trade. While having a reputation for harassing other fishes in home aquariums, it is not aggressive in roomy accommodations.

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Polka-dot stingray, Potamotrygon leopoldi

This species has a restricted range in South America, found only in the Xingu River Basin of Brazil, creating a concern that mining or other polluting activities could threaten it. Because of its striking pattern, it is highly valued for aquarium displays, and is now being captive bred around the world.

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