The Insane Biology of: The Orca

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In every ocean in the world, from coastal shorelines to the tropics to the poles and the endless deep expanses, lives the most widespread creature in the world after humans. Through the centuries, it’s been given many names: blackfish, grampus, and whale killer. While the seas are full of creatures vying for their place on the food chain, the orca is unequivocally on top.

Their Latin name, *Orcinus orca*, is derived from the name Orcus, the god of the underworld and champion of death—an apt reference to their fierce hunting reputation. They are the ultimate apex predator of the ocean, hunting everything from fish to seals and sea lions, to humpback whales and even great white sharks.

It’s not just what they hunt, but how they do it that sets them apart from every other animal. In the case of great white sharks, orcas will chase them down in packs and ram into their sides. The blow stuns the shark, allowing the orca to flip the great white over and hold it upside down, which paralyzes and drowns it. The orcas don’t simply eat the shark either; they carefully extract and consume just the livers with almost surgical precision. Great whites are so terrified of orcas that if a shark escapes an encounter with an orca, it will immediately flee the hunting ground and stay away for up to a year.

Packs of Antarctic orcas use cunning tactics, such as working together to create waves to wash seals off floating ice. Other groups swim in circles around schools of fish, blowing bubbles while slapping their tails on the water to corral the fish to the surface, where they can be easily caught. They have been seen to coordinate hunts with as many as 50 individuals and are constantly innovating new, often terrifying hunting methods.

Hunting strategies like this have fascinated scientists for years because of their apparent military precision. How are orcas able to communicate and coordinate such complicated concepts? How do they come up with so many new ideas and implement them so effectively? While many of these answers are still being uncovered, research is starting to reveal just how powerful the orca collective can be.

Though often called killer whales, orcas are more specifically in the dolphin family, of which they are the largest member. Today, they are the apex predator of the sea, but their evolutionary story didn’t always take place there. Fifty million years ago, a land-dwelling wolf-sized creature called *Pachycetus* lived along the edges of a shallow ocean, where it ate fish and other small sea creatures. Over the next eight million years, some of its lineage slowly ventured more and more to sea, exploiting more ocean resources and trading its legs for flippers.

Remnants of today’s whales’ land-dwelling origins can be found in their front flippers, where there are arm, wrist, and finger bones, and in their vestigial pelvic bone—a bone which serves no purpose today but is simply a leftover from when they had hind legs.

Today, orcas are one of the most recognizable animals in the ocean, with their distinct black and white coloring and immense size. Males can reach over 9 meters long and weigh up to 10 metric tons—about the size and weight of a school bus. They can propel their huge bodies through the water at a remarkably fast speed. An orca’s body is cylindrical and tapers at each end to form a hydrodynamic shape. This shape, along with the orca’s size and strength, makes it the second fastest marine mammal, reaching speeds of up to 35 kilometers an hour. At times, they’ve been seen leaping 15 feet into the air, and you would not want to be their target. Their bite force exceeds 131 megapascals; for reference, a great white’s bite force is estimated to be only 27.5 megapascals.

Acting alone, their size, speed, and powerful jaws would likely be enough to put them at the top of the food chain in the ocean, but they don’t operate alone. Orcas almost always work together in pods. The pod is a family unit based on the maternal group. A typical mature line consists of an older female or matriarch and her male and female descendants. These groups work together in sometimes perfect synchrony, with a precision that is hard for scientists to comprehend.

The basis for this teamwork is likely a refined and complex form of communication. We don’t know yet exactly what they’re saying, but researchers believe that their huge repertoire of sounds, calls, and whistles communicates complex messages to one another. In the 1970s, scientists started to record and analyze the numerous sounds orcas make beneath the waves in an attempt to gain insight into their mysterious underwater language.

First, they heard many clicks called click trains. These are the sounds the whales use for echolocation as they look for food sources and map their underwater environment with sound. To create a click train, the orca takes a breath, and pressure from streams of air bubbles moves up the airway from the lungs. This causes two flaps called the phonic lips to slap together. The clicking vibrations are then transferred to their bulbous forehead, aptly called their melon. The melon is an organ made up of specialized fats that help sound propagate. The clicks are organized into a beam as they travel through the melon, and the sound is emitted outwards as a series of high-frequency clicks that spread through the water like a flashlight beam. Each click lasts less than one millisecond, with frequencies ranging from 20 to 60 kilohertz and levels recorded over 220 decibels.

Decibels underwater are measured slightly differently than in air, making this seem extreme, but it is still incredibly loud. If the sound waves hit an object, some sound waves bounce back to the whale in the form of an echo. Specialized fatty tissues in the jaw area pick up the sound, and auditory nerves conduct it to the middle ear and brain, where it creates a picture of the environment for the orca. Echolocation allows killer whales to detect fish at distances of up to 500 feet—much further away than they could see in the dark, murky water. They can even differentiate the acoustic signatures of different swim bladders of various fish species to ensure they get their favorite kind.

Killer whales in the North Pacific, for example, prefer to eat almost exclusively Chinook salmon, whose range exceeds 15,000 square miles. This huge area is occupied by hundreds of other species of fish, including five other species of salmon, whose populations are often far more abundant than the Chinook salmon. Yet, the orcas can pinpoint and hunt down just the fish they want. Their echolocation is astoundingly precise.

Next, researchers focused on a different sound the orcas were making: whistles. Whistles are high-pitched, show a high degree of directionality, and are highly modulated. As a result, they don’t carry far underwater. Whistles are narrowband tones with few harmonic components at frequencies typically between 1.5 and 18 kilohertz and durations up to 12 seconds. They can even extend into the ultrasonic range, with frequencies ranging up to 75 kilohertz in some populations. Because they don’t travel far in water, scientists realized that these are the sounds the whales make when they want to have close-range private communication with their pod mates, which likely helps them coordinate certain attacks in relative secrecy.

Then there are the orca calls, as loud as jet engines, that echo over many miles in the ocean. These pulsed calls are the most common vocalization of killer whales. They show sudden and patterned shifts in frequency based on the pulse repetition rate, which is usually between 0.25 and 2 kilohertz. What’s surprising is that these vocalizations are not genetically predetermined; they are learned. When a calf is born, its first vocalizations are loud, high-pitched screams that bear no resemblance to the adults’ calls. But eventually, calves learn which calls to make and under what circumstances.

Scientists, however, have not yet learned the exact meaning of the orca language but know that it’s important for coordinating hunts. When orcas are working together during a herring hunt, for example, the sound underwater is off the charts—there are clicks, whistles, calls, sometimes with harmonic tones, and tons of undulation. Because of its learned nature and complexity, scientists believe that there is potential for communication of complex, specific information in calls—a true language being spoken.

Researchers are processing hundreds of hours of audio data from tagged animals in an attempt to correlate the sounds to certain behaviors to understand how exactly they communicate during hunts. Using artificial intelligence, scientists hope to one day be able to literally translate whale language into ours, perhaps even allowing us to converse with another species. Recently, an AI was developed that can translate one human language to another without help from a Rosetta Stone or key. Taking this one step further to decipher whale language may not be that far-fetched. Researchers are already working on training their AI to identify call types, find possible sub-units, and detect recurring communication patterns. This correlated with observed behavioral patterns may one day decode the orca’s language.

But beyond giving hunting signals, orca language serves another purpose: it is the basis for every orca pod’s group identity—an identity so solid that orca pods, in a sense, have cultures as rich and varied as our own. This culture, this group identity, sets them apart as the most effective predators in the ocean.

Though many pods of orca often live in close proximity to each other, they can lead wildly different lives. A type of pod called resident pods lives in relatively predictable locations, largely around coastlines, such as the well-studied northern and southern residents off the coast of British Columbia. These are the most common types of orca, and many pods of resident orcas can live near each other—not exactly living and working together, but occasionally interacting. These pods typically have an average of 14 members but can have as many as 50, and they typically hunt fish.

Then there’s another type of orca called transient orcas that are far more rare. These elusive and mysterious whales occur sporadically in unpredictable locations, often staying submerged for much longer than residents, hugging the shore but staying out of sight. These transient orcas travel huge distances over their lives, with some pods known to travel between Alaska and California. Transient pods are much smaller, averaging around three members, and they typically hunt marine mammals like sea lions. Transient orcas do not interact with resident orcas.

It was clear to researchers from the beginning that orcas opted to live in these groups, but just how distinct these pods were from one another wasn’t revealed until the 1980s when researchers began to listen more closely to the different orca conversations happening under the waves. What they found was that each pod has its own collection of calls, referred to as their very own dialect. One group of resident orcas, for example, relied on calls that begin with a low pulse rate burst followed by a simultaneous narrowband tone, which begins at a frequency of three to five kilohertz and then increases to over eight kilohertz. Another group of resident orcas uses a different type of call altogether—a low-frequency gradually rising tone followed by a lower pitch pulse, which is then followed by a sudden shift to a high-frequency tone and ending with another low-pitched burst. Resident orcas can have dozens of identifiable calls like this, each completely unique to their specific pod.

The difference in calls between resident and transient orcas, even in the same area, gets even bigger. Transient whales overall are very quiet compared to the residents. When they are foraging, they’re usually completely silent—not even using echolocation, which is heard in abundance in resident pods. But all transient orcas studied in the Pacific Northwest shared one type of distinct call, usually used while foraging, and even then they did so rarely—a long, quiet, low-frequency call.

The different orca dialects often go unchanged within a pod for decades, indicating that they’re likely an essential way to maintain group identity. This group identity is the key to their unrivaled success. A cultural species behaves differently than a species where everything is determined genetically. With each orca dialect comes a suite of wildly varied behaviors from group to group, each with particular traditions that allow them to carve out a specialized niche, hunting a particular target with a sophisticated, sometimes terrifying strategy.

The killer whales off the coast of Argentina have perhaps the most startling tradition of all. It was first observed in 1985, and scientists could hardly believe what they were seeing. When the tide is high and the sea is calm, the orcas snag sea lions directly from the shore by intentionally beaching themselves. Like a terrifying tsunami, the orca surfs on an advancing wave until it’s close enough to grab the unsuspecting sea lion from the tumultuous surf zone. Sea lions are notoriously clumsy on land, and during the transition from swimming to walking in shallow and turbulent water, by the time they notice danger approaching, it’s usually too late to escape.

Once grounded, the whale arches its body with its head and tail lifted and rocks sideways. This motion orients it parallel to the beach, and a subsequent wave helps to lift it off the bottom. The whale can then swim back into deeper water carrying the prey in its mouth, where it will eat it or share it with its pod. This intentional beaching technique is a tricky maneuver; it’s not easy for the orcas to synchronize their movements with the waves coming in and then back out, and if they miscalculate, they risk getting stuck, which can prove deadly.

There are 30 orcas that live along this stretch of coastline, but only 13 orcas have mastered the stranding technique. To reach this level of mastery, they have gone through years of rigorous teaching and training. Young orcas can be seen with older adults practicing repeatedly, beaching themselves without trying to catch any prey. Sometimes the older orca introduces a prop, like seaweed, to enrich the training. It’s always females who teach the young orcas, and they do so with remarkable care and patience. Some young whales never make it through the training; the feeling of going aground and the sensation of their entire body weight out of the water can be enough to deter them from trying again. Only a few ever get the hang of it. The young orca’s first attempt to catch live seals might not happen for years, and when it does, they still need the assistance of an adult to return to the water with their prey.

This shows that learning hunting techniques requires a high degree of skill and significant parental investment to reduce the associated risk. Though difficult, time-consuming, and dangerous, the social transfer of skills like this through apprenticeship is one of the key reasons orcas are so highly adaptable and thus such formidable predators throughout the world.

The culture and groups of orcas are so profound that scientists even believe that orcas are the only non-human organisms whose evolution is driven by culture. Just as some humans have evolved to tolerate lactose as cow milk became increasingly introduced to our diets, orcas too are evolving due to their choices and traditions. Transient orcas are even so distinct from resident orcas that scientists believe it’s only a matter of time until they become their own species—not because geography separated them, but because culture did.

But there’s one more key ingredient without which none of the orca’s complex culture would be possible: the orca’s giant brain and incredible intelligence. Orcas have the second biggest brain in the animal kingdom, after sperm whales, weighing in at a whopping 5.4 to 6.8 kilograms. However, exactly how brain size translates to intelligence is not straightforward. Scientists have found that while absolute size is important, its size relative to the body is more so. The larger the brain is relative to the body, the more brain weight might be available for more complex cognitive tasks.

One measure called the encephalization quotient (EQ) tries to measure this ratio and is used to convey how small or large a species’ brain is compared to other species with a similar body size. Orcas are near the top of the list. Humans have the largest EQ at about seven, bottlenose dolphins are next with an EQ of around four, and orcas follow at about 2.5.

Beyond this impressive brain-to-body ratio compared to other mammals, the orca brain is highly unusual because it has extremely pronounced wrinkling and folding in the cerebral cortex. This wrinkling, called gyrification, increases the amount of total cortical nerve tissue that processes information, making brains with more wrinkles and folds able to handle more data and process it faster. Cetaceans, the toothed whales and dolphins, have significantly higher gyrification compared to land mammals. The gyrification index for humans is 2.2, for bottlenose dolphins it’s 5.6, and for orcas, it’s 5.7—the most gyrified brain in the world.

Yet perhaps the most fascinating structure in an orca’s brain is its extremely developed insular cortex. The insula is involved in consciousness and the regulation of emotions like compassion, empathy, interpersonal experience, and self-awareness. This means the orca may be emotionally intelligent in the same way we are aware of the feelings of others and aware of its own existence. This may be the ultimate measure of consciousness in the animal kingdom.

In 2001, researchers put orcas to the test—a test to gauge if orcas do indeed have a sense of self by determining whether they can recognize their own reflection in a mirror as an image of themselves. This was done surreptitiously by marking the black part of their rostrum with white ointment and the white part with dark green ointment, observing whether the animal reacts in a manner consistent with being aware that the dye is located on its own body. Such behavior might include turning and adjusting the body to better view the marking in the mirror.

The orcas in the study not only noticed the markings but seemed to be completely fixated on them. They had spent time in front of mirrors before, but with the markings, they seemed unable to look away. They blew bubbles at their reflection, bobbed their heads, and stuck their tongues out—all these behaviors were unusually frequent and lasted longer than at any time before the markings were placed.

While this is not necessarily a sign of consciousness as we know it, it is not unreasonable to think that the orca mind works similarly to ours and that they are capable of high-level thinking and feeling, perceiving the vast complexity of the world they live in. In a highly intelligent, dominant social species where the young are taught difficult lessons over many years and where family takes care of each other, it’s hard not to see a reflection of ourselves in them. Even though we diverged from the orcas many millions of years ago, they may be our closest counterpart in the way we both experience this world.

The more we observe the orca world, the more the incredible complexity of their lives becomes clear to us.