An Amazon River Dolphin (Inia geoffrensis) eating an armored catfish

An Amazon River Dolphin (Inia geoffrensis) eating an armored catfish

Among the rarest and most endangered of mammals are the beautiful river dolphins, a group of magnificent freshwater cetaceans which live in certain huge river basins in Asia and South America.  Up until today, science knew about the Ganges River Dolphin (Platanista gangetica), the Amazon River Dolphin (Inia geoffrensis), the Bolivian river dolphin (Inia boliviensis), the Yangtze Dolphin (Lipotes vexillifer), and the La Plata River Dolphin (Pontoporia blainvillei).  I have a weakness for river dolphins and each of these incredible species is worthy of a much longer post!  In fact my ill-fated toy company, River Dolphin Toys, was named for the botu, the playful pink river dolphin of the Amazon River (but, alas, making good toys is no substitute for being well-organized, ruthless, and severe). China’s Yangtze River Dolphin was one of the prettiest animals alive but it is now functionally extinct (the tale behind the mass death of these beautiful white dolphins is a profoundly sad story of modern China which I will tell some other day when we all feel stronger).  The Ganges dolphin is swiftly going extinct because of…actually, let’s cover the known river dolphins some other time.  Today’s news is about the new river dolphin species which was just discovered: the Araguaian river dolphin, Inia araguaiaensis!

The Araguaian river dolphin (Inia araguaiaensis) eating a fish.  Can you spot the differences? (photo by Nicole Dutra)

The Araguaian river dolphin (Inia araguaiaensis) eating a fish. Can you spot the differences? (photo by Nicole Dutra)

The Araguaian dolphin lives in the Araguaia River (a tributary of the Tocantins River) in a rainforest watershed habitat very much like the Amazon.   Araguaian dolphins look nearly identical to Amazon dolphins and were long regarded as a subspecies.  Both river dolphins are clever alpha predators of the river with sharp wits and long toothy rostrums for catching tasty freshwater fish.  As it turns out however, the two species diverged 2 million years ago when the rivers became separate.  Despite a similar appearance to the Amazon River dolphin, the Araguaian dolphin has a larger brain case and different genetic makeup.  Araguaian dolphins do not interbreed with either of the other two known Inia dolphin species (although I have no idea how scientists discovered this fact).  The “new” dolphins are threatened by deforestation, fishing, and hydroelectric dams.  Indeed, biologists speculate that only a thousand individuals are left in their population.  Hopefully the Brazilian people will find a way to protect the lovely and intelligent animals before they too vanish forever.

Tocantins_watershed