From: Jeremy Hance, MONGABAY.COM, More from this Affiliate
Published July 15, 2013 11:21 AM

Forgotten Species: The Arapaima or 'Dinosaur Fish'

Everyone knows the tiger, the panda, the blue whale, but what about the other five to thirty million species estimated to inhabit our Earth? Many of these marvelous, stunning, and rare species have received little attention from the media, conservation groups, and the public. This series is an attempt to give these 'forgotten species' some well-deserved attention.

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Let's go back some 14,000 years (or up to 50,000 depending on who you talk to), since this is the first time humans encountered the meandering, seemingly endless river system of the Amazon. Certainly, the world's first Amazonians would have been astounded by the giant beasts of the region, including ground sloths and mastodons (both now extinct), as well as giant anteaters, armadillos, and tapirs, currently the biggest land animal on the continent. But these first explorers might have been even more surprised by what dwelled in the rivers: anaconda, caiman, and the arapaima. Wait, the what?

"Arapaima are like living fossils, they are among the oldest [freshwater] fish on the globe. Only found in the Amazon and Essequibo River drainages, they are among the largest freshwater fish in the world reaching up to ten feet in length!" explains Lesley DeSouza with Chicago's John G. Shedd Aquarium, which is supporting conservation efforts of the arapaima in Guyana.

Due to its massive size and the fact that its virtually unchanged in the fossil record for 23 million years, DeSouza says the arapaima has become known as the "dinosaur fish." And while the species never actually lived during the time of the dinosaurs, its primeval appearance certainly brings the popular image of prehistoric beasts to mind.

This monster fish can weigh between 200-400 pounds (90-180 kilogram), and likely served as a hugely-important food source for the first peoples of the Amazon, just as it does for many indigenous tribes today. Although the bulk of the arapaima is the most instantly noticeable feature of the fish, many aspects of its natural history set it a part.

"Arapaima are obligate air breathers, which means they have to come up for air every 10—20 minutes," DeSouza told mongabay.com. Arapaima evolved this behavior due to low oxygen levels in Amazon rivers; while the fish do not have proper lungs, they have evolved special tissue in its swim bladder that process oxygen.

Until humans arrived on the scene, arapaima were the top predators in their river systems. Nothing dared eat them, for they sport incredibly tough, but flexible, armored scales that can't even be penetrated by piranha teeth; the scales are so effective that engineers are studying them for modern applications.

Continue reading at MONGABAY.COM.

Arapaima fish image via Shuterstock.

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