Mahakam River's Miracle: The Secrets of Dolphins with Flexible Necks and Advanced Sonar

In the Mahakam River of East Kalimantan, Indonesia, lives one of the most unique freshwater mammals in the country. The Mahakam dolphin (Orcaella brevirostris) is not only a regional icon but also an intelligent animal with various biological capabilities that help it survive in the riverine environment. Unlike fish, dolphins breathe with lungs, give birth, and nurse their young. Their birthing process is also unique. Calves emerge tail-first, a method that helps reduce the risk of the baby inhaling water before its entire body is out. Newborn calves also have fine hairs around their snouts, a sign that dolphins are mammals, though these hairs disappear as they grow. After birth, the young will nurse from their mother's mammary glands located on the lower part of her body, near the anal area. Another unique feature is their flexible neck. Unlike most dolphins, Mahakam dolphins can move their heads in various directions. This ability makes it easier for them to maneuver and find prey in the murky, shallow, and branched river. Vision is not their only reliance. These mammals are equipped with a highly sophisticated sonar system. They emit high-frequency ultrasonic sounds and read the echoes to identify objects, determine direction, and locate fish or shrimp. Meanwhile, lower-frequency sounds are used for communication with their own kind. The Mahakam dolphin also has an interesting hunting strategy. They can spray water from their mouths to startle or confuse prey. Similar behavior is also observed during play and interaction, indicating a high level of intelligence. Even when resting, Mahakam dolphins never fully sleep. Part of their brain remains active so they can control their breathing and surface to take in air. This article was originally published on Mongabay