Maddie Bender
Wed, August 17, 2022
At the risk of awarding the title prematurely, we think we’ve found the weirdest study published in 2022. Scientists strapped GoPro cameras to the bodies of six dolphins trained by the U.S. Navy, and recorded them hunting for food and consuming their prey in grisly detail. According to the study, there was a purpose behind this potential invasion of dolphin privacy; namely, to learn more about how the mammals hunted and ate.
Scientists have previously made two competing assumptions about how dolphins ate. They engaged in either ram feeding, in which the predators swim faster than their prey and clasp the fish in their jaws as they overtake them; or suction feeding, in which predators move their tongues and expand their throats to create negative pressure and slurp up prey. The authors of the study, which was published on Wednesday in the journal PLoS ONE, set out to determine which method dolphins actually used.
“[S]ound and video together have never been used before to observe the behavior of dolphins and of the live fish they capture and consume,” they wrote in the study.
Photo Illustration by Kelly Caminero / The Daily Beast / Getty
And, of course, there’s the fact that these dolphins were trained by the U.S. Navy. The Marine Mammal Program as it’s called today has existed in some form since before 1960, when Navy researchers attempted to improve torpedo design by studying dolphins. Since then, they have spent millions of dollars annually to foster and train bottlenose dolphins and California sea lions. According to the program’s website, these animals “have excellent low light vision and underwater directional hearing that allow them to detect and track undersea targets, even in dark or murky waters”—and unlike human divers, they don’t suffer from the bends.
Ridgway et al.
Still, the existence of a Navy program to train dolphins to identify targets like deep-sea mines does not explain why this study was conducted. And because Sam Ridgway, the lead author of the research and a founder of the Marine Mammal Program, passed away earlier this year, it does not seem like we will ever know the answer to this pressing question. We must instead hew to the text of the study itself, which is helpfully written like dolphin fan fiction. Here is a passage explaining what the GoPro footage of the three dolphins hunting looked and sounded like:
“Squeals continued as the dolphin seized, manipulated and swallowed the prey. If fish escaped, the dolphin continued the chase and sonar clicks were heard less often than the continuous terminal buzz and squeal. During captures, the dolphins’ lips flared to reveal nearly all of the teeth. The throat expanded outward. Fish continued escape swimming even as they entered the dolphins’ mouth, yet the dolphin appeared to suck the fish right down.”— Ridgway et al.
The angle of the cameras’ present a view of dolphin side eye that we have never before seen, nor care to see again. Up close, it is clear that these are not idyllic Lisa Frank dolphins; these are terrifying, nightmare-inducing Roman dolphins that seem to crave the thrill of the chase. The study, which is the Marine Mammal Program’s 330th peer-reviewed article, details how “it became apparent” when the dolphins had identified their next target: The animals picked up speed, as observed by an increase in the sound of the water as they whooshed through, and their heartbeats became audible in the recordings.
It is important to remember that there was a scientific purpose to this pseudo-horror movie footage. The researchers found that for the most part, the dolphins engaged in suction feeding, not ram feeding. “We were surprised by the ability of all of our dolphins to open their upper and lower lips” to suck in food, they wrote.
Ridgway et al.
But wait! The GoPros also captured a dolphin eating sea snakes, which has never before been observed: “It is notable that on one day, dolphin Z preyed on 8 yellow bellied sea snakes. The dolphin clicked as it approached the snake and then sucked it in with a bit more head jerking as the flopping snake tail disappeared and the dolphin made a long squeal.”
You’re welcome.
Read more at The Daily Beast.
Videos from dolphins with GoPros strapped to their sides reveal they hunt venomous sea snakes and emit eerie 'victory squeals'
Videos from dolphins with GoPros strapped to their sides reveal they hunt venomous sea snakes and emit eerie 'victory squeals'
Morgan McFall-Johnsen
Thu, August 18, 2022
A dolphin with a camera attached to the left side of her harness.US Navy/National Marine Mammal Foundation
Dolphins with GoPro cameras on them captured incredible up-close footage of their hunting habits.
The videos surprised scientists, as the dolphins used suction to feed and ate venomous sea snakes.
Watch the dolphins' point of view and hear their sonar clicks and victory squeals as they hunt.
Video footage from GoPro cameras strapped to a pair of Navy-trained bottlenose dolphins reveals the ocean animals' hunting habits up close for the first time.
Scientists at the National Marine Mammal Foundation fixed the dolphins with their cameras and set them loose in the San Diego Bay. They captured hours of video and sounds that reveal a few secrets of dolphin life.
Step-by-step view of a Navy dolphin using suction to capture, rotate, and swallow a fish in the Pacific Ocean.US Navy/National Marine Mammal Foundation
It turns out that the animals use suction to feed, swallow venomous sea snakes, and squeal in victory after a successful hunt.
One video, below, shows the dolphin's face as it tracks a fish, grabs it, and swims a victory lap. It's not just the footage that's incredible. The dolphin's creaky and echoing calls are equally revealing. The dolphins emitted sonar clicks as they searched for prey. As they approached a fish, the clicks sped up to become a buzz, punctuated with a squeal as they caught and swallowed their meal.
from Vimeo.
The research was led by Sam Ridgway, a prominent marine-mammal scientist who earned nicknames like "Dolphin Doctor" and "the father of marine mammal medicine," before he died in his San Diego home in July.
Sam Ridgway was known as the father of marine-mammal science.
from Vimeo.
Did you catch that? It went quickly.
A sea snake (indicated with pink arrow), moments before it is captured and eaten by a Navy dolphin.US Navy/National Marine Mammal Foundation
That's a yellow-bellied sea snake, and it's highly venomous. Scientists assumed that's why they'd only observed dolphins playing with snakes and releasing them, not consuming them — especially not consuming eight of them.
Ridgway and his co-authors couldn't believe their eyes at first. They searched for other fish that might look like a sea snake on camera, but they found no other explanation.
"I've read that other large vertebrates rarely prey on the yellow-bellied sea snake. There are reports of leopard seals eating and then regurgitating them. This snake does have the potential to cause neurotoxicity after ingestion and its venom is considered fairly dangerous," Dr. Barb Linnehan, director of medicine at the National Marine Mammal Foundation, said in a statement emailed to Insider.
The dolphin showed no signs of illness after its sea-snake meals, the researchers reported.
"Perhaps because the snakes ingested were thought to be juveniles, they had a lower amount of venom present," Linnehan said.
Dolphins appear to be suction feeders
The sea-snake footage is also revealing because the dolphin caught its prey in the open ocean, indicating that it used suction to capture and swallow its food. Researchers previously assumed that bottlenose dolphins use a technique called ram feeding, where they capture prey simply by clamping their jaws around it.
Images from a dolphin's camera show its eye closely tracking the fish it's catching (left) and its lips curled and throat expanded after it's caught the fish (right).
Videos from dolphins with GoPros strapped to their sides reveal they hunt venomous sea snakes and emit eerie 'victory squeals'
Morgan McFall-Johnsen
Thu, August 18, 2022
A dolphin with a camera attached to the left side of her harness.US Navy/National Marine Mammal Foundation
Dolphins with GoPro cameras on them captured incredible up-close footage of their hunting habits.
The videos surprised scientists, as the dolphins used suction to feed and ate venomous sea snakes.
Watch the dolphins' point of view and hear their sonar clicks and victory squeals as they hunt.
Video footage from GoPro cameras strapped to a pair of Navy-trained bottlenose dolphins reveals the ocean animals' hunting habits up close for the first time.
Scientists at the National Marine Mammal Foundation fixed the dolphins with their cameras and set them loose in the San Diego Bay. They captured hours of video and sounds that reveal a few secrets of dolphin life.
Step-by-step view of a Navy dolphin using suction to capture, rotate, and swallow a fish in the Pacific Ocean.US Navy/National Marine Mammal Foundation
It turns out that the animals use suction to feed, swallow venomous sea snakes, and squeal in victory after a successful hunt.
One video, below, shows the dolphin's face as it tracks a fish, grabs it, and swims a victory lap. It's not just the footage that's incredible. The dolphin's creaky and echoing calls are equally revealing. The dolphins emitted sonar clicks as they searched for prey. As they approached a fish, the clicks sped up to become a buzz, punctuated with a squeal as they caught and swallowed their meal.
from Vimeo.
The research was led by Sam Ridgway, a prominent marine-mammal scientist who earned nicknames like "Dolphin Doctor" and "the father of marine mammal medicine," before he died in his San Diego home in July.
Sam Ridgway was known as the father of marine-mammal science.
US Navy/National Marine Mammal Foundation
Ridgway helped found the US Navy's Marine Mammal Program more than 60 years ago. That's the program that trained the dolphins in this study. He also founded and led the National Marine Mammal Foundation, the nonprofit behind the new paper. He dedicated his entire career to understanding the behavior, physiology, and health of ocean mammals — especially bottlenose dolphins.
These videos are one of his final research efforts. For the first time, Ridgway and his team captured up-close video and sound of dolphins hunting and eating live fish. A paper about the footage was published in PLOS ONE on Wednesday.
"Dr. Ridgway was very proud of these findings and was ecstatic to know that this culmination was going to be published in PLOS ONE," Brittany Jones, a scientist at the National Marine Mammal Foundation who worked with the study authors while they completed their paper, told Insider in an email.
"He was always eager and excited to review the video and audio of these fish-capture sessions and recently spoke of his appreciation and admiration for [co-authors] Dianna Samuelson Dibble, Mark Baird, the amazing animals, and the animal care staff that made this research possible," Jones said.
One dolphin's diet included venomous sea snakes
Shocking to the researchers, one dolphin ate eight venomous sea snakes — a behavior never observed before in dolphins.
The video below shows one of those sea-snake meals. After catching the snake, the dolphin jerks its head and emits a high-pitched "victory squeal."
Ridgway helped found the US Navy's Marine Mammal Program more than 60 years ago. That's the program that trained the dolphins in this study. He also founded and led the National Marine Mammal Foundation, the nonprofit behind the new paper. He dedicated his entire career to understanding the behavior, physiology, and health of ocean mammals — especially bottlenose dolphins.
These videos are one of his final research efforts. For the first time, Ridgway and his team captured up-close video and sound of dolphins hunting and eating live fish. A paper about the footage was published in PLOS ONE on Wednesday.
"Dr. Ridgway was very proud of these findings and was ecstatic to know that this culmination was going to be published in PLOS ONE," Brittany Jones, a scientist at the National Marine Mammal Foundation who worked with the study authors while they completed their paper, told Insider in an email.
"He was always eager and excited to review the video and audio of these fish-capture sessions and recently spoke of his appreciation and admiration for [co-authors] Dianna Samuelson Dibble, Mark Baird, the amazing animals, and the animal care staff that made this research possible," Jones said.
One dolphin's diet included venomous sea snakes
Shocking to the researchers, one dolphin ate eight venomous sea snakes — a behavior never observed before in dolphins.
The video below shows one of those sea-snake meals. After catching the snake, the dolphin jerks its head and emits a high-pitched "victory squeal."
from Vimeo.
Did you catch that? It went quickly.
A sea snake (indicated with pink arrow), moments before it is captured and eaten by a Navy dolphin.US Navy/National Marine Mammal Foundation
That's a yellow-bellied sea snake, and it's highly venomous. Scientists assumed that's why they'd only observed dolphins playing with snakes and releasing them, not consuming them — especially not consuming eight of them.
Ridgway and his co-authors couldn't believe their eyes at first. They searched for other fish that might look like a sea snake on camera, but they found no other explanation.
"I've read that other large vertebrates rarely prey on the yellow-bellied sea snake. There are reports of leopard seals eating and then regurgitating them. This snake does have the potential to cause neurotoxicity after ingestion and its venom is considered fairly dangerous," Dr. Barb Linnehan, director of medicine at the National Marine Mammal Foundation, said in a statement emailed to Insider.
The dolphin showed no signs of illness after its sea-snake meals, the researchers reported.
"Perhaps because the snakes ingested were thought to be juveniles, they had a lower amount of venom present," Linnehan said.
Dolphins appear to be suction feeders
The sea-snake footage is also revealing because the dolphin caught its prey in the open ocean, indicating that it used suction to capture and swallow its food. Researchers previously assumed that bottlenose dolphins use a technique called ram feeding, where they capture prey simply by clamping their jaws around it.
Images from a dolphin's camera show its eye closely tracking the fish it's catching (left) and its lips curled and throat expanded after it's caught the fish (right).
US Navy/National Marine Mammal Foundation
In the videos from the dolphin with a camera on its side, however, the researchers could see the dolphin's lips opening, tongue withdrawing, and throat expanding. They think all these subtle movements increase the space in the dolphins' mouths and create negative pressure for suction.
"With years of experience in feeding dolphins, we had not noticed this lip motion," the researchers wrote in their paper. "Rather than seizing fish in a 'claptrap' of the toothy beak, dolphins appeared to mostly suck in fish."
In the videos from the dolphin with a camera on its side, however, the researchers could see the dolphin's lips opening, tongue withdrawing, and throat expanding. They think all these subtle movements increase the space in the dolphins' mouths and create negative pressure for suction.
"With years of experience in feeding dolphins, we had not noticed this lip motion," the researchers wrote in their paper. "Rather than seizing fish in a 'claptrap' of the toothy beak, dolphins appeared to mostly suck in fish."
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