15 February 2007

Blind as a . . . Dolphin?

Platanista gangetica (Blind River Dolphin)

There are only four species of river dolphins. Or were, I should say, since the Baiji, or Yangtze River Dolphin, may now be extinct. The others are the the Amazon River Dolphin, the La Plata Dolphin (which inhabits saltwater estuaries off the coast of S. America), and the Blind River Dolphin of India.

Two subspecies of the Blind River Dolphin Exist. The Indus, and the Ganges, inhabiting these rivers respectively. One of the most interesting facts about this species is that it is blind. It has eyes, but no lenses, meaning it can detect light, but cannot resolve images. Instead, it has a highly developed sonar system, similar to bats. It emits pulses of sound, which it uses to find prey and navigate through the river.

It is likely that less than 2000 of these animals are still alive in India. They suffer from the damming of the rivers, pollution, poaching, and habitat degradation. Conservation has been hampered, in part, because of the difficulty of obtaining information on populations and their movements and habits.

Now, technology has been developed by the Japanese which will allow scientists to identify and track individual dolphins. The device is an underwater hydrophone that can differentiate between the clicks of different dolphins, which are unique to each individual.

No comments: