Amazing Creatures-Dolphin Human Companion

IT LOVES warm, shallow tropical waters, whether salty or fresh, murky or clear. Its range covers an area from India’s Bay of Bengal through the Malay Archipelago to northern Australia.

Yet, few people—especially Australians, whose northern doorstep may hold the largest concentrations of this animal in the world—have ever seen or even heard of the Irrawaddy dolphin. Surprising? Yes and no.

In the 19th century, zoologist John Anderson saw schools of this bluish-gray dolphin, with its round, beakless head, in the Irrawaddy River in Myanmar (then Burma). He gave it the name Irrawaddy dolphin.

                                                               Why Rarely Seen

Irrawaddies thrive in hot and humid coastal, estuary, and river regions. Their home is often flanked by mud, mangroves, jungle, clouds of mosquitoes and, in places, even crocodiles—not the surroundings that attract humans.

The water in these areas is also generally murky, so the only time you would see a dolphin is when it briefly surfaces to breathe. Even then, it keeps a low profile. Little of its back appears, and its dorsal fin is small compared with that of other dolphins.

But in some places Irrawaddy dolphins are not such a rare sight. Fishermen and riverboat operators working the Irrawaddy River in Myanmar, and other rivers in the dolphin’s Asian domain, frequently see the animals hunting and cavorting far upstream, even squirting jets of water from their mouths like water fountains or figurines in a water garden.

In Australian waters, the Irrawaddies range along the west coast, around the top of the continent, and down the east coast. They are usually seen in groups numbering fewer than 6 but occasionally up to 15. Unlike their Asian kin, the down-under clan have never been known to mimic water fountains.

                                                                  Is It a Dolphin?

Irrawaddies live near land and are slow swimmers compared with their more sprightly blue-water cousins. Yet, scientists have had difficulty studying them. Their uninviting domain is a key factor. However, live Irrawaddies have been studied in the Jaya Ancol Oceanarium, in Djakarta, Indonesia.
Because little is known about Irrawaddies, until recently biologists were unsure where they fit on the whale-dolphin family tree. Obviously, they have much in common with dolphins. Yet, in form, not color (they range from pale to dark bluish-gray), they could almost pass for a smaller version of the Arctic beluga whale, or white whale. Even their unusually flexible neck is much like that of the beluga. So, what are they—the equatorial equivalent of the beluga or a true dolphin?

One way to find out is to load a broad range of their anatomic and genetic features onto the measuring scales, so to speak, and see which way the scales tilt. The weight of evidence, it turns out, falls on the dolphin side of the scales.