If you’ve ever had trouble catching your breath, try catching a dolphin’s.
The plume produced when these “whales” come up for air could reveal signs of how healthy they are. But capturing samples of the spray from agile, skittish wild dolphins is challenging. To make the task easier, a team of engineers has turned to the dolphin’s chuff. This is the forceful exhale that sends water, air and mucus hurtling skyward from the animal’s blowhole. Their first step: getting good data on the fluid’s flow.
The researchers started with high-speed video of captive Atlantic bottlenose dolphins. Those videos revealed that each chuff lasts around a quarter of a second.
The chuff begins with a brief spurt of water flung off the top of the blowhole. Then comes a second wave: the exhale. That powerful outflow produces a turbulent jet moving at a maximum speed of nearly 100 kilometers (62 miles) per hour, notes Alvin Ngo. He’s an engineer at Oklahoma State University in Stillwater. He and his colleagues presented these data November 24 in Seattle, Wash. They were taking part in the American Physical Society’s Division of Fluid Dynamics meeting.
The expelled mucus contains health indicators. One is a stress hormone known as cortisol. Understanding these chuffs could help scientists design drones to swoop in and sample the spray. That could turn up information on the animals. For instance, it might show whether the animal’s pod is being stressed by human activity. In the past, researchers used drones to sample spouts from whales. However, dolphins produce less spray. And that can greatly complicate sampling efforts.