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!