A pair of Navy dolphins, with cameras attached to their sides, is the first to be seen chasing and catching prey in a natural environment using both video and sound.
As specified in a Newsweek report, dolphins that have video cameras strapped to them have been recorded, producing excited noises as they caught prey, which included yellow-bellied sea snakes, in the San Diego Bay and the open ocean.
This footage enabled researchers to compare the sounds produced by the dolphins to the behaviors they were displaying.
According to research, dolphins that were inquest for their prey produced different sounds when they approached and when they caught their would-be meal. The same study specified too, that dolphins constantly kept their eyes on the prey.
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This handout photo from the U.S. Navy shows Spetz, a bottlenose dolphin belonging to Commander Task Unit 55.4.3 beach up on a transfer mat before going out on a training mission from the well deck of the USS Gunston Hall on March 17, 2003, in the Arabian Gulf.
Vocalizing for Echolocation
One of the dolphins was also observed eating eight yellow-bellied snakes, which are venomous species that had never been seen being preyed upon by dolphins. It did not fall ill.
Also mentioned in the research published in PLOS One, dolphins are vocalizing for various reasons, frequently for echolocation when searching for prey.
The click rate for such vocalizations is believed to increase when reaching an object of interest. They are communicating with one another using tier vocalizations. They even have signature whistles within their social group, almost similar to a name.
In the paper, the researchers reported that placements of the camera that they used could be used with tiny cameras and suction cup tags "to observe feeding in wild dolphins." The study authors added this would provide better insight into feeding and nutrition in endangered populations.
Strange Dolphin Behavior
When chasing prey, the dolphins were observed to click at 20- to 50-millisecond intervals. These were trimmed into a terminal buzz, a series of quick subsequent clicks, sounding akin to high-pitch buzz, and then a sequel as the dolphin reached a potential catch.
As the dolphin caught and ate the prey, the squeals continued, deviating in duration, peak, amplitude, and frequency.
The squeal and terminal buzz continued even if the fish fled and the dolphin gave chase. If the eye of the dolphin was visible in the footage, the study authors discovered that "it was always rotated toward the fish."
Simultaneous video and sound of all prey capture occurrences, and some fish that fled capture showed that echolocation, which is described in National Geographic, was used to find prey at a distance and up close vision demonstrated by eye tracking was used as well.
Catching and Eating More from the Bottom
The San Diego Bay dolphins, in particular, were observed in numerous sessions of approximately 50 minutes and discovered that while the dolphins fed on prey, both at the water's surface, and close to the seabed, they caught and ate more from the bottom.
One dolphin, in particular, caught 64 fish from close to the seabed and five close to the surface while the other was captured at the bottom and four at the surface.
Scientist Brittany Jones, from the National Marine Mammal Foundation, said such findings are an outstanding to the literature offering detailed analyses during prey capture in the open ocean, which would be quite difficult to attain with wild dolphins.
Related information about army dolphins is shown on Real Science's YouTube video below:
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