How dolphins use tools, teamwork and trickery to get their dinner

There is no doubt that dolphins are incredibly smart. But how they use their intelligence to survive continues to amaze marine biologists, who discover new and fascinating behaviors every year.

There are 36 known species of dolphin, from the 110-pound Maui dolphin to the camper-sized killer whale, and they all face the same battle: how do you catch food without limbs?

One of the most studied species, the common bottlenose dolphin, has developed an impressive array of hunting strategies, such as mud ring feeding. With a few powerful strokes of their tails and a circular swim, these predators round up a school of fish in a tornado of mud. To the fish, the plume looks like an impenetrable wall, causing them to panic and try to jump over the barrier at the water’s surface. Unfortunately for them, other hungry dolphins with open jaws are waiting there. (Watch dolphins catch fish with a mud ‘net’.)

Until recently, mud ring feeding was thought to be unique to only a few populations of bottlenose dolphins living in Florida. But a recent study published in the journal Science of marine mammals proves that the behavior is more common than previously thought, and has been confirmed in Belize and Mexico, said study leader Eric Ramos, a marine biologist at the City University of New York.

While it’s technically possible that a dolphin feeding the mud may have brought the behavior from Florida to the Caribbean, or vice versa, Ramos deems that explanation unlikely. Instead, he believes that separate dolphin populations living in similar habitats have independently innovated the same strategy.

“It’s really cool either way,” Ramos says — and it’s just one of the many clever ways dolphins have learned to survive.

Beach feeding: the most dangerous game

It is very dangerous for a marine mammal to get too close to the coast, where the animal can become stranded and die. However, some dolphin species willingly take the risk by chasing fish onto the beach – then swallowing them in before squirming back in its wake.

“It’s so dangerous,” said Janet Mann, a behavioral ecologist at Georgetown University in Washington, DC, who studies the behavior of Indo-Pacific bottlenose dolphins from Shark Bay, Australia.

In fact, Mann says that one of the most prominent “beach” dolphins, a female named Jamaica, actually showed up a few years ago with burns, likely caused by prolonged sun exposure after getting stuck on the shore.

Beach feeding, or beaches, is another rare strategy known only in a handful of places, such as South Carolina and Shark Bay. “It’s very interesting behavior because there are only a few animals that do it,” Mann says. (Learn how dolphins have bold and shy personalities like us.)

Kerplunking: playing with your food

When a dolphin slaps its caudal fin or tail on the surface of the water, it may seem like a toddler is playing in a bathtub. But this is actually deadly serious hunting behavior.

Depending on where they live in the world, the dolphins can use their tails to stun fish and even shoot them into the air before going in to kill. This is known as fish kicking or fish whacking. (Watch dolphins fish out of the water to stun and eat them.)

Some Australian bottlenose dolphin populations perform a maneuver where they knock octopuses out of the water in an attempt to disarm the sucker-footed cephalopods before devouring them.

Other times, a dolphin’s thump may serve a different purpose. Some dolphins in Australia’s Shark Bay will storm the water’s surface while foraging with their noses in the seagrass below, perhaps to scare away fish. Scientists have called the behavior kerplunking.

Cooperative foraging: putting food on the table

Many animals work together to tackle prey, as dolphins do when engaged in mud ring feeding. But very little tag team with people to do it.

In Laguna, Brazil, bottlenose dolphins drive fish to the shore where fishermen wait. With water up to the chest and hands full of line, the fishermen cast their nets as the dolphins approach.

“The advantage for the fishermen is that they obviously catch a lot more and sometimes bigger mullet fish if they follow the signals from the dolphins,” says Mauricio Cantor, a behavioral ecologist at Oregon State University. “Especially because the water can be very murky, so you simply can’t see where the fish are.”

Of course, the dolphins can “see” them just fine using their built-in sonar called echolocation. And they also benefit, Cantor says, because the fishermen and their nets act as a barrier against which to drive the fish. It’s so successful, there are records of such teamwork going back about 120 years in Brazil.

Cooperative foraging also occurs in another dolphin species, the freshwater Irrawaddy dolphin of Myanmar (Burma).

Sponges and shelling: tools of the trade

Since the 1980s, researchers have tracked several dozen dolphins in Shark Bay who practice the art of ‘sponging’, an example of the use of tools. (Discover our interactive way of how animals use tools.)

This happens when a dolphin plucks a sponge from the seabed and pushes the soft animal on its nose, probably for protection as it plows along the rocky seabed in search of fish. Sponging also allows the predators to deter small fish that may hide from the predators’ natural sonar.

Sponging is more than a hobby, Mann says: It makes dolphins culturally different from their neighbors, according to her research.

“Sponges really stand out as more lonely and less sociable,” she says. And when they socialize, sponges tend to form cliques with other sponges. Most interesting of all, she says, is that sponges seem to be passed from mothers to daughters. “One of the females discovered in 1984 is still sponging,” Mann says. “She is 37 years old.”

Even less common is a behavior known as “shooting,” in which a person chases a fish into an empty shell. (Read how Indo-Pacific bottlenose dolphins prepare a “recipe” for squid.)

“The dolphins stick their mouths into the opening of the shell, bring it to the surface and then shake it so that the fish basically falls into their open mouths,” said Sonja Wild, a behavioral ecologist at the University of Konstanz in Germany, who will start in 2020. an investigation led to shelling among Shark Bay dolphins.

Oddly enough, shelling behavior is transmitted horizontally, while sponging is only learned vertically. In other words, dolphins can learn shells from their friends, but sponges are kept within the family.

With satellite imagery and drones, as well as the proliferation of smartphone cameras, it’s likely that scientists will continue to add new discoveries to the already long list of dolphin foraging behaviors, says Ramos of the City University of New York.

“Technology gives us access to things we could never see before.”

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