Visit to Encante - dolphins of the Amazon region

Animals, March, 2000 by Sy Montgomery

"Tucuxis," Nildon Athaide, our guide, announced over the roar of the 15-horsepower motor. In Brazil, these small gray dolphins are still called by the name the Mayanas Indians gave them in the Tupi language. We recognized them as the species scientists call Sotalia fluviatilis--the other Amazon dolphin that shares these waters with the boto. But unlike botos, tucuxis look and act the way we expect of dolphins: with their neat, compact bodies, short, well-defined snouts, and triangular dorsal fins, they launch out of the water, leaping and spinning, leaving arcs of spray as they spurt along the water's surface. Perhaps 50 yards from our boat, first one leapt, then the other, revealing soft, pinkish bellies; then the two leapt together, almost touching. Dianne Taylor-Snow and I grabbed each other's hands. "First the symphony," she yelled at me over the motor, "then the opera--and now the ballet."

Everyone likes the tucuxis, Vera da Silva, the director of the aquatic-mammal lab at INPA, an Amazon research institute, had told us. River people tend to be suspicious of the big botos, who approach boats so close and so suddenly. But the tucuxis are not as bold. They perform their joyous leaps at a distance, and they are small and pretty. Only four to five feet long, tucuxis look like miniature marine dolphins, elegant and streamlined, their bottle-snouts split with cheerful smiles.

Within the whale order, which includes the dolphins, Sotalia is classed in the Delphinidae, the same family as the marine dolphins who swim in the seas. In fact, until relatively recently, tucuxis almost certainly were exclusively marine dolphins, for even today they can be found in both fresh and salt water, ranging from southern Brazil to Honduras.

Although there are no fossil records of Sotalia, most scientists agree that these dolphins entered the Amazon from the Atlantic, probably no earlier than 5 million years ago. But the botos are representatives of a very different whale lineage. Until recently, botos were classed with the other five species of river dolphins in the Platanistidae, the family to which the dolphins we had seen in Bangladesh and India belong; but now many scientists believe that the boto and one related species, the La Plata dolphin of southeastern South America, should make up their own family, the Iniidae.

The boto's big body, which may stretch to eight feet long and weigh 400 pounds, is quite different from most dolphins'. It lacks a prominent dorsal fin, possessing only a low ridge along the back. The flippers are huge, almost like wings. But it is the face that is most arresting: compared with the tucuxi's neat, smooth head, the boto's bulbous forehead seems misshapen, like a troll's or a dwarf's. The eyes are tiny. The face ends in a tube-shaped beak, which often curves to one side as if it has gotten bent.

American scientists David and Melba Caldwell, who studied captive botos in Florida, described them as "beady-eyed, humpbacked, long-snouted, loose-skinned holdovers from the past." But there is a strange beauty to the boto: it is like the beauty of the very old and the beauty of the fetus. Theirs is the beauty of becoming, or a creature poised on the brink of becoming something else.