River Dolphins: A Glance At Freshwater Cetaceans

On September 24, 2014 by Tim Newman

Dolphins are normally associated with the open ocean, and rightly so, because that’s where the vast majority of them live. But not all of them dwell in the salty deep.

There are five river dolphin species in all, and one recently extinct version. All of these dolphins are odd-looking in their own right and have specific adaptations that have evolved separately to deal with the freshwater world they’ve found themselves in.

River dwelling cetaceans are thought to have colonised rivers after being out-competed by ocean-going dolphins in the wilds of the cut-throat seven seas.

Here’s a short rundown of some of these oddly shaped, freshwater wonders:

Chinese River Dolphin – Baiji

Sadly the baiji, also known as “Goddess of the Yangtze”, is now defined as “functionally extinct“. The baiji only lived in the Yangtze river, and as of 2004 none have officially been seen alive. An expedition to search for baiji in 2006 returned without a single sighting, some video footage which may show baiji was taken in 2007, but it can not be confirmed. The likelihood is that the population is too small to recover even if there are some stragglers left behind.

The Baiji suffered the consequences of industrialization and all the pollution and bedlam that goes with it. The Yangtze is over 1000 miles long and 12% of the entire population of earth live and work in its vicinity. Humans are dirty and water mammals aren’t keen on filth; human pollution in combination with major dam projects put increasing pressure on the poor old baiji.

India’s Ganges River Dolphin

The South Asian river dolphin is found in the Ganges and Brahmaputra Rivers. These mighty rivers sprawl though Bangladesh, Nepal and Pakistan making this particular river dolphin one of the most cosmopolitan of the gang.

The Ganges River dolphin has a particularly long and pointy snout which is characteristic of most river dolphins. From millennia spent in muddy rivers the Ganges dolphin has developed a crystalline eye lens becoming pretty much blind, maybe only seeing light and dark patches. Like other dolphin species their primary hunting tool is echolocation.

The weirdest thing about the Ganges River dolphin is that it’s the only cetacean that swims on its side. I guess if it’s blind it wouldn’t notice and its friends wouldn’t notice to tell him either.

The species has suffered at the hands of human pollution, lowered water levels and fishing nets and is now considered endangered. They are protected but the occasional unlucky individual is caught by locals who use the mammal’s oil and meat as an aphrodisiac and as bait for catfish. If they were catching them to eat I could understand, but aphrodisiacs and bait? OMG.