Toss and slap — how dolphins disarm a dangerous meal
© KATE SPROGIS/MUCRU
A group of hungry dolphins off the coast of Western Australia have figured out how to eat a dangerous meal. It’s octopus. And if eaten alive, it can stick in the throat. The dolphins, though, know how to immobilize their prey, a new study finds. They shake and toss it until the head falls off, the animal is in pieces and its arms are tender and no longer wiggling.
Most people who dine on octopus also prefer it immobile. We cut it into pieces and grill or otherwise cook it. Some people do eat live octopus. They may consider the wiggly, armed entree a treat. But this isn’t a meal to be eaten carelessly. Those sucker-covered arms can stick to the throat and suffocate the diner if the entree has not first been chopped into small pieces.
Dolphins risk the same fate. “Octopus is a dangerous meal,” notes Kate Sprogis. She’s an ecologist at Murdoch University in Australia. “The suckered arms would be difficult to handle considering dolphins don’t have hands to assist them,” she says.
But Sprogis and her colleagues turned up dolphins that have figured out how to eat octopus safely. Their behavior, never before reported, was discovered during observations of bottlenose dolphins between March 2007 and August 2013. These marine mammals live in waters off of Bunbury, Western Australia. Researchers witnessed 33 events in which the dolphins used either of two techniques to turn a wriggly octopus limp. Sprogis’ team shared what it learned April 2 in Marine Mammal Science.
In one technique, a dolphin held an octopus in its mouth and shook it. The dolphin then slammed its prey into the water’s surface until the meal was in pieces. Another method involved repeatedly flinging the octopus into the air until it was ready to eat.
Story continues below image.
Each dolphin would repeat its preferred motion, or combine the two, usually around a dozen times. After several minutes of this, the battered prey was safe to eat.
“If the dolphins haven’t prepared their meal enough, then this can cause problems,” Sprogis notes. There have been two dead dolphins found in this area with whole octopuses lodged in their throats.
Dolphins have picked up a reputation for tackling difficult-to-eat foods in creative ways. Some have been spotted using cone-shaped sponges to flush out little fish from the sandy ocean floor. Others use a six-step process to prepare a meal of cuttlefish.
The Bunbury dolphins eat both octopus and cuttlefish. Those meals appear to be more common in the winter and spring, when waters are cooler, Sprogis notes. That may be when the octopus and cuttlefish breed and lose some of their camouflage. And that would make them easy prey for dolphins brave or with enough know-how to take advantage of the potential meal.
behavior The way something, often a person or other organism, acts towards others, or conducts itself.
bottlenose dolphin A common species of dolphin (Tursiops truncate), which belongs to the order Cetacea among marine mammals. These dolphins are found all over the world.
breed (noun) Animals within the same species that are so genetically similar that they produce reliable and characteristic traits. German shepherds and dachshunds, for instance, are examples of dog breeds. (verb) To produce offspring through reproduction.
camouflage Hiding people or objects from an enemy by making them appear to be part of the natural surroundings. Animals can also use camouflage patterns on their skin, hide or fur to hide from predators.
colleague Someone who works with another; a co-worker or team member.
cuttlefish Lesser-known members of the cephalopod family, which includes octopuses and squid. Hunting by night, cuttlefish use their big eyes and arms with suckers. Masters of disguise, these animals can hide in plain sight by changing their colors to blend into their surroundings.
dolphins A highly intelligent group of marine mammals that belong to the toothed-whale family. Members of this group include orcas (killer whales), pilot whales and bottlenose dolphins.
ecology A branch of biology that deals with the relations of organisms to one another and to their physical surroundings. A scientist who works in this field is called an ecologist.
mammal A warm-blooded animal distinguished by the possession of hair or fur, the secretion of milk by females for feeding their young, and (typically) the bearing of live young.
marine Having to do with the ocean world or environment.
marine mammal Any of many types of mammals that spend most of its life in the ocean environment. These include whales and dolphins, walruses and sea lions, seals and sea otters, manatees and dugongs — even polar bears.
octopus Sea mollusks with a soft, sac-shaped body and eight tentacles. Two rows of suckers along each tentacle give the animal an ability to grasp and hold onto things. Cousins of the squids, these animals have a sharp beak-like mouth and good vision.
prey (n.) Animal species eaten by others. (v.) To attack and eat another species.
sponge A primitive aquatic animal with a soft, porous body.
suffocate To be unable to breathe, or to cause a person or other organism to be unable to breathe.
Journal: K.R. Sprogis et al. Complex prey handling of octopus by bottlenose dolphins (Tursiops aduncus). Marine Mammal Science. Published online April 2, 2017. doi: 10.1111/mms.12405.