Dolphin Feeding, Hunting and Getting High | Sea Life, Islands and Oceania

FEEDING DOLPHINS

Amazon dolphin eating a big fish

Dolphins, porpoises and toothed whales primarily feed on fish, squid, and crustaceans. They generally grab prey with their toothy jaws and swallow it whole in their multi-chambered stomachs. Dolphins eat about 20 to 30 pounds of fish a day. They eat many mackerel, squids, blue fish and herring. These fish provide them with water as well protein, vitamins and calories. [Source: Robert Leslie Conley, National Geographic, September 1966]

Dolphins catch flying fish by jumping out of the water and stunning their prey with a head butt before eating it. Some dolphins chase schools of fish onto the shore and then climb up on land and eat them. At Shark Bay in Australia, dolphins briefly beach themselves to grab fish after driving the fish up onto the shore. This technique was spread "vertically," mainly through the female dolphin population, from mother to daughter.

Joshua Foer wrote in National Geographic: They have proved ingenious at discovering feeding strategies that are particular to the environments they inhabit. In the shallow waters of Florida Bay dolphins use their speed, which can exceed 20 miles an hour, to swim quick circles around schools of mullet fish, stirring up curtains of mud that force the fish to leap out of the water into the dolphins’ waiting mouths. Dusky dolphins off the coast of Patagonia herd schools of anchovies into neat spheres and then take turns gulping them down. [Source: Joshua Foer, National Geographic, May 2015. Kenneth Norris, National Geographic, September 1992]

A video recorded in November 2022, shows the chaotic moment a group dolphins attacked a massive school of tens of thousands of salmon off Australia’s southern coast near the coastal town of Merimbula. The video was shot by blogger Jason Moyce — known as “Trapman Bermagui” — who posted on Facebook: “I didn’t see the dolphins at all till they just turned up while filming. “I could hear the noise from 100 meters (328 feet) away. Incredible to watch in real life.” [Source: Mark Price, Miami Herald, November 14, 2022]

According to the Miami Herald: His video reveals it only took a few dolphins to create the panic. The predators are seen charging into the school of fish, then quickly exiting (likely with their mouth full). Prior to the attack, the “monster school” of salmon blanketed the shallow seafloor and was shown moving in slow, hypnotic circles. Australian salmon gather in such schools to feast on smaller bait fish, experts say. That means the video captured overlapping feeding frenzies. It was one of two dolphin attacks Trapman Bermagui recorded along the rocky shoreline, and the second video appears to show the dolphins herding the salmon like sheep to their doom.

Dolphin Group Feeding

dolphin barrier feeding strategy

Pacific white-sided dolphins have been observed working as a team to attack schools of herring by coming at the school from all sides and pushing it near the surface into a tight mass and then plucking away at herring on the edge. If the school attempts to retreat the dolphins use bubbles and physical force to keep it a tight mass. Often seabirds show up to join in on the feast. Dolphins, seal lions and sharks have been seen together hunting stragglers from large schools of fish off South Africa.

Bottlenose dolphins that live in waters off South Carolina form small groups of a half dozen or so that move inshore to fish in winding channels between sand bars and low flat islands. These dolphins have to make decisions about the tide, the presence of fish and other factors to determine the best places to feed. They often make snap judgments at a given moment and need to communicate and relay information back and forth between members.

Describing the South Carolina dolphins on the hunt, David Attenborough wrote: “At low tide, the falling water exposes narrow strips of mud between the water’s edge and the reed bed beyond. The dolphins swim back and forth in a rough semicircle from one end to another of such a mud-bank, moving closer and closer to it. Then, with perfect synchronization the suddenly come together to form a line abreast with their flanks almost touching, and charge towards the mud bank, driving shoals of small fish ahead of them. They swim so fast and with such power they create a bow wave that sweeps them and the fish right out of the river and up on the mud. As the water drains away, the dolphins roll over on their flanks and snap up the fish with the sides of their mouths. They all turn in the same direction — always on their left flank...Then the dolphins, flapping their bodies energetically, wriggle back into water and swim further up river to repeat the performance on another mud-bank.”

Critter Cam Study of Dolphins Hunting

Video cameras attached to bottlenose dolphins have given scientists remarkable insight into how dolphins hunt, search for prey and squeal with delight when they snag something. One dolphin is even seen hunting and eating several venomous sea snakes. The videos, released in August 2022, are an “incredible addition” to the scientific knowledge of dolphins hunting in the open ocean, biologist Brittany Jones of the National Marine Mammal Foundation, a nonprofit group based in San Diego, said. The scientists observed “eye movements, capture strategies, and movements of the lips, tongue, muscles, and gular [lower jaw] region during prey capture events which would be very difficult to achieve with wild dolphins.” [Source: Tom Metcalfe, NBC News, August 18, 2022]

NBC News reported: For the latest study the researchers fitted six U.S. Navy dolphins — identified in the study only as B, K, S, Y, T and Z — with a harness and underwater video camera that could record their eyes and mouths. The cameras also made audio recordings of any noises. Study co-author Dianna Samuelson Dibble, a foundation biologist, said although the dolphins in the study aren’t wild, they have frequent opportunities to hunt in the open ocean and the scientists expect wild dolphins hunt in much the same way.

Of special note are the sounds they make while hunting. The dolphins made “clicks” every 20 to 50 milliseconds as they looked for prey, a rapid noise that only they can hear clearly and which seems to be a form of echolocation — the natural sonar sense used by dolphins, porpoises and toothed whales to detect fish by bouncing sounds off them. “It became apparent during video analyses when the dolphins had identified the next prey target,” Dibble said in an email. “The background noise would quickly intensify, masking many dolphins’ sounds as the animal picked up speed in pursuit. The dolphins then began making a buzzing sound as they closed in, followed by a squeal of victory when they caught their prey. “The buzzing and squealing was almost constant until after the fish was swallowed,” she said.

How Dolphins Hunt

Maddie Bender wrote in The Daily Beast: 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 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. [Source: Maddie Bender, Daily Beast, August 18, 2022]

The scientists said: “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. They wrote: “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.”

The videos show that dolphins also use their eyes to track prey at close range. “As the dolphins approached prey, it was evident that the visible eye was oriented toward the fish,” Dibble said. “At times we see a ring of skin deformation surrounding the eyeball that is probably indicative of eye muscle contractions.” Fish near the surface would sometimes jump into the air in a desperate attempt to escape, but the dolphins were able to stay on target. “The dolphin would swim ventrally [almost upright] while tracking the prey visually and capture the fish as it landed back in the water,” she said. [Source: Tom Metcalfe, NBC News, August 18, 2022]

Dolphin Feast on Venomous Sea Snakes

In the video described above, according to NBC News, one intrepid animal, dolphin Z, was seen on video hunting and devouring eight yellow-bellied sea snakes in one day, apparently without suffering any ill effects, although they’re known to be extremely venomous and have made other marine mammals vomit. The researchers said: “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.” Scientists think the snakes were juveniles that had not developed strong venom, and that wild dolphins may be taught by other members of their group to avoid them. [Source: Tom Metcalfe, NBC News, August 18, 2022]

According to Business Insider: Dolphins have never been documented eating sea snakes, only playing with them. The attacks puzzled scientists, since consuming venomous snakes can be dangerous. In one video, the dolphin catches a snake and swims around with it for a while, jerking its head repeatedly to swallow the prey. Then it emits a high-pitched "victory squeal," according to the study. "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," the study authors wrote. [Source: Morgan McFall-Johnsen, Business Insider, August 20, 2022]

At first the researchers didn't believe their eyes. 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.

Dolphins Use Sea Sponges and Shells to Obtain Food

Dolphins at Shark’s Bay Australia have been observed pushing around large pieces of sponge. It is believed they use them as a mask for protection again things like stingrays and sea anemones when they bottom feed. If this the case his is the first known use of tools among wild dolphins. The practice seems to have originated among one female who taught the trick to other females — which some anthropologists say makes it a form of culture, or at least a socially-learned technique. In the years after the behavior was first observed only one male was seen doing the trick.

According to Nature: Sponge-using bottlenose dolphins were first described in 1997 in Shark Bay, 850 kilometers north of Perth, Australia. Since then, all dolphins known to use this tool have come from the same bay, and the vast majority have been female. Direct observations have been rare, but researchers think the dolphins use the marine sponges to disturb the sandy sea bottom in their search for prey, while protecting their beaks from abrasion. [Source: Andreas von Bubnoff, Nature, Published: 06 June 2005]

In August 2011 Reuters reported, “Dolphins in one western Australian population have been observed holding a large conch shell in their beaks and using it to shake a fish into their mouths — and the behavior may be spreading. Researchers from Murdoch University in Perth were not quite sure what they were seeing when they first photographed the activity, in 2007, in which dolphins would shake conch shells at the surface of the ocean."It's a fleeting glimpse — you look at it and think, that's kind of weird," said Simon Allen, a researcher at the university's Cetacean Research Unit. "Maybe they're playing, maybe they're socializing, maybe males are presenting a gift to a female or something like that, maybe the animals are actually eating the animal inside," he added. [Source: Reuters, August 29, 2011]

Do Dolphins Use Toxic Pufferfish to Get High?

Dolphins appear seem to use toxic pufferfish to get high Footage from a new BBC documentary series, "Spy in the Pod," reveals what appears to be dolphins getting high off of pufferfish. Pufferfish produce a potent defensive chemical, which they eject when threatened. In small enough doses, however, the toxin seems to induce "a trance-like state" in dolphins that come into contact with it, the Daily News reports:

“The dolphins were filmed gently playing with the puffer, passing it between each other for 20 to 30 minutes at a time, unlike the fish they had caught as prey which were swiftly torn apart. Zoologist and series producer Rob Pilley said that it was the first time dolphins had been filmed behaving this way. [Source: Rachel Nuwer, Smithsonianmag.com, December 30, 2013

“At one point the dolphins are seen floating just underneath the water's surface, apparently mesmerised by their own reflections. The dolphins' expert, deliberate handling of the terrorized puffer fish, Pilley told the Daily News, implies that this is not their first time at the hallucinogenic rodeo.

Image Sources: 1) Wikimedia Commons; 2) NOAA; 3) Mikurashima tourism

Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.

Last Updated June 2023