Scientists Strapped a GoPro on Dolphins and Then They Noticed Something Very Strange

Scientists released Dolphin S from her netted enclosure after strapping GoPro cameras on her body, calling her to follow their boat. Out in the waters of San Diego Bay, the boat came to a stop. Dolphin S was now free to forage and roam wherever she desired. Once set free, Dolphin S drilled into the waters to catch a fish. She found one, as seen in the footage shared by scientists as part of a study published in the journal PLOS One.

Once she had decided upon a plan, Dolphin S approached the fish. The first chase was unsuccessful. The fish escaped. But Dolphin S didn’t give up. She continued the chase and eventually succeeded in gripping the fish in her mouth. While the fish flailed and agitated, Dolphin S slurped it down. In the footage, Dolphin S can be seen making groaning sounds all the way while feasting upon the prey. Once the fish had been gobbled up, she coughed up the plant matter and seafloor sediment back into the ocean.

The team recorded 15 periods of footage from Dolphin S, each spanning a duration of 50 minutes. She wasn’t the only dolphin to be studied. Several dolphins were strapped with cameras and sound traps. As they glided through the ocean waters, the researchers observed the actions and strategies they employed while eating live bass, fish, croakers, halibut, smelt, and pipefish. Dolphin K, for instance, ate eight venomous yellow-bellied sea snakes from the San Diego waters. And she turned out just fine. "Our dolphin displayed no signs of illness after consuming the small snakes," reported the researchers.

The objective of this study was to know the strategies and techniques dolphins employ for foraging, feeding, and hunting. GoPro cameras attached to the back and sides of these predators displayed distractingly odd angles of their mouths and eyes. Typically trained to work in undersea mines and guard America’s nuclear stockpiles, these dolphins were utilized for research.

The clips and recordings collected from these cameras revealed some astonishing insights about the behaviors of these dolphins. One, for example, revealed that these mammals use not just vision, but also sound to locate fish. Another observation was that instead of ramming into the prey, they used suction to gulp or slurp them down as they seized and swallowed them. All the while they attacked the prey, they made sounds of clicking, buzzing, and squealing, all of which were recorded in the sound traps.

"As dolphins hunted, they clicked almost constantly at intervals of 20 to 50 milliseconds. On approaching prey, click intervals shorten into a terminal buzz and then a squeal. On contact with fish, buzzing and squealing were almost constant until after the fish was swallowed," the researchers write in the paper. Most mammals use two techniques for hunting and eating – either slurping up the prey directly within their mouths or ramming them down like a sandwich. Most of the observed dolphins appeared to use the former technique, that is, by slurping the fish down their throats.

According to the footage, seen in close-up mode, the dolphins appeared to suck the fish in from the sides of their open mouths by expanding their throat muscles and withdrawing their tongues out of the way. If a fish succeeded in escaping, like the one in the case of Dolphin S, the dolphin continued to chase. “The dolphin’s lips flared to reveal nearly all of its teeth. The throat expanded outward. The fish continued to escape, swimming even as they entered the dolphins’ mouths, yet the dolphins appeared to suck the fish right down,” the researchers described in the paper. The research pinpoints the mechanism driving the intricacies of a dolphin’s intelligence.

You can watch the footage of Dolphin S chasing her prey below: