Comparing an orca's brain to a human's explains why killer whales are the ocean's ultimate apex predator
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- Orca and human brains have similar features that give them high-functioning abilities like empathy.
- Orcas also have a high sense of self-awareness, which they use to develop unique hunting tactics.
- Orcas also have very wrinkly brains, which enables them to think and process information quickly.
Although orcas are technically dolphins, their size and ferocity have earned them the nickname "killer whale."
They've been known to hunt virtually anything in the water, including blue whales, great white sharks, and even boats.
Orcas can swim up to 30 miles per hour and have sharp teeth to tear into their prey, but their most dangerous weapon is actually their brain.
Orca and human brains are very similar
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An orca brain is five times larger than a human's, but it has many of the same structures that ours do.
For example, orcas' highly developed insula and cingulate sulcus give them self-awareness, understanding of social relationships, and empathy. These heightened skills come in handy for their hunting tactics.
Moreover, "cetaceans like orcas and bottlenose dolphins also have a uniquely elaborated brain area called the paralimbic system," said Lori Marino, founder and president of The Whale Sanctuary Project and a neuroscientist who studies cetacean intelligence.
In fact, the paralimbic system has much more intricate folding and detail in orca brains than in humans'.
It's unclear what the advantage may be, but based on their knowledge of other brain areas, scientists think this intricate paralimbic system helps combine information from the parts of the orca's brain that process emotions with those in charge of higher-level thinking.
Orcas understand the power of numbers
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Orca social groups, or pods, can range from five to 30 orcas, but pods can team up in even larger groups for a big hunt, like when 80 orcas took down a 59-foot blue whale in 2021.
Video showed how the orcas corralled the whale toward the surface, and then in groups of six to eight, they took turns body-slamming the whale and rolling over its blowhole so it couldn't breathe. The hunt took over three hours.
Plus, their large numbers helped ward off rival predators, including pilot whales and a hammerhead shark, from stealing the food.
Each pod has its own unique hunting techniques that target its prey's weaknesses. For example, Antarctic seals are different prey entirely from blue whales.
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A fleeing seal may take refuge on ice floes, but they don't stay safe for long. The orcas can create choppy waves that break up the floes, and the seals slide straight into their waiting mouths.
This is made all the more impressive because pods pass down not just their hunting techniques, but also their unique "dialect" of communicative clicks and whistles to offspring across generations.
Orcas are one of the only other creatures besides humans to have evolved this level of complex culture, per the Orca Network.
Orcas are masters of echolocation
But it's not just orcas' similarity to humans that makes them so deadly. It's also their differences that make them the sea's apex predator — in particular their brain's ability to detect and process sound.
Sound travels four times faster in water than air, and orcas take advantage of that by sending out pulses, clicks, and whistles to scan the area around them like radar — an ability called echolocation.
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"Orcas are very good at detecting the direction of sound," Marino said. They use echolocation not just to communicate with each other and detect obstacles, but also to hunt prey, and even target specific organs within that prey.
Case in point, orcas can use echolocation to detect fish up to 500 feet away and use it to identify the size of the fish and go for larger prey, like older Chinook salmon.
Echolocation may also help explain how killer whales along the coast of South Africa — who seem to love the taste of fatty, high-calorie shark liver — have been observed tearing away the liver on the first bite. They must know where the liver is located, and echolocation might help explain why.
Marino said calculating the origin and nature of each sound they hear likely requires "very complex neurobiological computations." Scientists believe orcas are able to do these calculations thanks to the shape of their wrinkly brains.
Orca brains are very, very wrinkly
Most mammals have the same basic brain structure: a wrinkly outside of gray matter, where all the nerve endings pass off messages to each other. Underneath the surface lays the white matter, which acts like cables connecting nerve endings in different parts of the brain.
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Usually, the larger an animal's brain, the more white matter they need to, hypothetically, keep all the nerve endings connected. But cetaceans, including orcas, don't follow this rule.
Instead, they evolved exceptionally wrinkly cortexes with a bunch of extra gray matter folded in on itself.
Orcas have the wrinkliest brains of any animal, even humans, per Orca Nation. The folds on the surface of their brains bring nerve endings closer together, so it takes less time and energy to send messages back and forth.
This rapid nerve communication lets orcas register, process, and react to sounds faster than almost any other animal in the ocean. In other words, they think fast and are quick on their feet — er, fins in this case.
Between orca's tactical teamwork, their hyper-sensitive echolocation, and overall intelligence, their prey rarely stand a chance.
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