Orcas have incredible eyesight both in and out of the water, making them uniquely suited to hunt both fully aquatic and aquatic-adjacent sea life. There is some speculation that this eyesight, combined with their complex echolocation, is what allows orcas to be so specific in the prey they eat. This also contrasts many other species of marine mammals, including some of the larger whales, which may be another way that killer whales have advantage over the creatures they hunt.
Going back to our Salish orcas, this ability to distinguish their specific preferred food source may start becoming a hindrance. They prefer Chinook salmon and have been seen refusing both sockeye and pink salmon, which are abundant in their area. They do this despite Chinook salmon becoming increasingly scarce. However, their excellent eyesight is likely part of what enables pods to coordinate large group attacks!
We spoke about killer whales having effective ocean camouflage, but some pods of orcas go even further than relying on their coloration. Orcas have been observed hiding in the dark of the ocean, completely silent, relying on their excellent hearing to passively track prey before going in for the kill. This behavior was noted in the far northern reaches, which sometimes only have a few hours of darkness. Therefore, it must be incredibly effective and efficient to keep the killer whales sustained.
This method is most often seen in the mammal-eating orca groups, such as transient and offshore groups, and is distinct from the pods which eat mostly fish. The fish-eating pods are exceptionally vocal, “talking” to each other often, while the mammal-eating groups often only vocalize after they’ve secured their kill. One scientist speculates that their burst of communication after a kill is largely because of the need for speed and precision in dismantling their prey! And while some scientists thought that the silent killer whales hunted by sight alone, the fact that they hunted in the dark shows that they can also rely on their excellent hearing to track and corner prey.
You wouldn’t think of a moose as being prey for an orca. After all, moose live primarily on land, while orcas live in the ocean. Both orcas and moose are the largest members of their relative species, and both have few – if any – natural predators. The current most dangerous creature in the lives of these species is man; though moose are herbivores, they’re considered an apex species through sheer size alone.
But there is a strange relationship between orcas and moose. In the summer, moose prefer aquatic vegetation, and will even dive to get it, which makes them vulnerable to killer whales. While killer whales don’t often hunt moose, there is anecdotal evidence – such as moose corpses washing up with distinctive killer whale bite marks – that shows that orca can and will eat moose. This makes sense, because orcas can be opportunistic predators, often willing to eat anything and everything they can sink their teeth into.
Perhaps one of the most fascinating details about orcas, especially those that hunt sharks and aquatic mammals, is that they have the ability to be choosy in what they eat. Despite needing hundreds of pounds of food a day to survive, killer whales have been observed eating only the fatty, nutrient-rich livers of sharks and leaving the rest of the shark behind. They even have a specific method to extract the liver! They’ll make a hole near the liver and simply squeeze it out of the shark, like we would squeeze toothpaste from a tube.
One scientist even observed a pod of killer whales attacking a blue whale, the largest animal known to have existed! Approximately 12 orcas repeatedly bashed into the blue whale, biting at it, and finally wore it down enough that they were able to force it underwater and drown it. Then, instead of feeding indiscriminately, they went for the tongue first! Sometimes, the tongue is the only part of the baby they eat, despite how much food they need to survive.
Although orcas aren’t the largest creatures in the ocean, they’re some of the deadliest. But still, you’d think that something would hunt them, right? Sharks, for example, are powerful predators known for being perfectly designed to kill and eat prey. Polar bears, though ostensibly a land animal, spend much of their lives in the sea. They’re often spotted hunting belugas, narwhals, and bowhead whales, and can be found hundreds of miles from land. Other toothed whales also exist, but most have evolved to hunt fish and squid, not mammals. Still, their sheer size should render them able to fend off a killer whale attack… right?
Wrong. Not even the great white shark will mess with a pod of orcas. Though many people see the great white as the apex predator of the ocean, these strong hunters will flee in the face of killer whales, sometimes never to return. Blue and gray whales, some of the largest marine life to ever exist, demonstrate timidity and even fear in the face of orcas; despite having large bodies and heavy tails that they often use to stun or kill other potential predators, they’re almost hesitant to attack an orca even if it’s actively attacking them! It’s largely suspected that the killer whale’s overall intelligence, skilled hunting methods, and pack behavior is what has secured them their rightful spot at the top of the ocean’s food chain.
While we’ve talked about how orcas have spread across the world, becoming distinctive in their preferred prey, it’s also true that some regional groups are known as generalist eaters. Rather than having a specific species or type of prey, these groups will eat anything they can get. Worldwide, marine biologists saw them eating 140 different kinds of animals, including over 50 different types of marine mammals!
Orcas in the Antarctic, specifically, have been seen hunting and eating penguins. The birds they chase are smaller, and orcas seem specifically interested in the breast meat of penguins. They often meticulously picking off feathers and skin – sometimes with the help of other orcas. This behavior is highly unusual to scientists. The killer whale may only get a pound or two of meat – if that – from each penguin. When they need to eat hundreds of pounds of food a day, being so picky about the penguin makes little sense for survival.
Orcas, like many other ocean-dwelling mammals, are manual breathers. Unlike humans, who have a subconscious reflex that keeps us breathing even in deep sleep, killer whales must choose when they breathe. That means that they can’t go completely unconscious like us or they would sink and die!
Instead, orcas practice something called “unihemispheric sleep,” where one half of the brain shuts down and the other stays alert. This lets the killer whales keep an eye out for danger and continue to breathe while still getting the rest they need. They switch which side of the brain is “turned off” to ensure that they’re getting enough rest! And while they’re not fully conscious, they’re still capable of travel; orcas that are sleeping will swim slowly and steadily, close to the surface of the water, so that they can easily breach whenever necessary.
We know, we know – but baby animals are so cute! Unfortunately, baby and adolescent animals are often the weakest and most vulnerable of a species, and so killer whales have become experts at eating the young of a variety of different species. This method of hunting is most often seen with seals and sea lions, but transient and offshore orcas have also been known to hunt baby gray and blue whales.
Their method of hunting involves attacking small pods or single family groups. They work together to separate a baby from the mother. Gray whales are particularly vulnerable to this type of attack. Why? Because they most often travel alone or in groups of no more than three, though marine biologists see some bigger pods. Once the orcas have succeeded in getting a whale calf separated from its mother, they will either drown it or start devouring it. However, some scientists speculate that killer whales will hunt baby blue whales for the sheer enjoyment of it. Why? Because sometimes spending hours working to kill the calf only to eat the tongue and leave the rest.
Because orcas only give birth once every 3-10 years, after a 17-month gestation, they’re incredibly protective of their young. Orca mothers will nurse juveniles for up to two years, and adolescent female orcas will often help care for the younger killer whales in the pod. Because pods are matrilineal, and hunting methods are passed from mother to child, it’s vital that adolescent orcas are given the opportunity to grow up. Mothers have even been seen holding single salmon in their mouths, allowing their calves to chew at the fish, and thus learn the preferred prey of their particular regional group.
Killer whales also ensure that calves have plenty of food. In the case of hunting larger prey, such as blue whales, orcas will dive down to the corpse as it sinks to tear off chunks to bring to the surface. Young orcas can’t dive as deep or for as long as mature killer whales. Plus, they need proportionally more food than mature whales (10% of their body weight as opposed to 2-3% for an adult killer whale). Thus, the pod makes sure the young get their fill. Sure, some juvenile killer whales will separate from their mother’s pod and move to another group. However, many choose to stay within the pod for their entire lives.
Perhaps one of the most fascinating – and most alarming – facts about killer whales is that they have their own distinct cultures. Much like humans, individual regional groups (and even pods within the regions) have their own dialects, accents, and preferences! A study of four “clans” of resident killer whales off the coast of British Columbia and Washington showed that despite overlapping ranges and close proximity, each clan had a totally unique “language.”
Other differences include some whales visiting rubbing beaches. They purposefully scratch themselves on pebbly rocks in the shallows, while other whales that are nearby don’t exhibit the same behavior. Salish Sea whales are known to be extremely playful and even have greeting ceremonies!