Three Amazing Orca Hunting Strategies: Orcas show a remarkable level of variation between groups. Like humans, orcas around the world differ in how they structure their social groups, how they behave, how they vocalize, and even what they eat. These group-specific behaviors are passed down from generation to generation, and, as some suggest, constitute cultures.
One especially fascinating aspect of orca culture is hunting. Just as a human can be leery of trying unfamiliar cuisine for the first time, orcas exhibit similar culinary caution. Essentially, orcas are picky eaters, and anything they encounter that isn’t on their family’s menu is generally ignored. As such, groups of orcas around the world have developed different hunting strategies, each specialized for their preferred prey.
These strategies are so creative, so clever, that it’s easy to see how they earned the name “killer whale.” Though orcas are apex predators, their hunting prowess is not attributable to their size, strength, and speed alone. Their true asset is their teamwork, which allows them to hunt safely and efficiently as a group. So, here are three remarkable strategies they’ve got up their sleeves:
New Zealand orcas seem to have developed a taste for rays, despite the risks posed by the ray’s venomous spines and foraging in shallow water. These orcas have figured out that the rays have a peculiar weakness: when you flip them upside down, they enter a state of paralysis called tonic immobilization. In some cases, the first orca will daintily pluck the ray out of hiding by its tail, then a second orca swoops in with a fatal bite to the head. Other times one orca will pin the ray to the ocean floor upside down, while another removes the stinger with its teeth.
This type of hunting requires teamwork, and one study reported that 60% of captured rays were shared amongst the group. Additionally, just as with observations of orca hunts in other unrelated populations, calves accompanied the adults but did not participate. This observation supports the notion that adults are teaching calves these specialized hunting behaviors, and that these behaviors constitute a form of learned culture.
SURFING FOR SEALS
In Punte Norte, Argentina, orcas capitalize on the fact that elephant seals and sea lions use the rocky shores as a place to birth and rear their young. The mothers of these newborn pups know better than to let their young roam into deeper waters, so the hungry orcas have to come to them. These orcas swim close to shore, waiting for the perfect alignment of the tides, the seals, and shore, to strike. When the opportune moment arises, the orca surfs a wave onto the shore, grabs a seal pup in its teeth, then rolls its body and uses another wave to pull it back to deeper water. In one study of this behavior, none of the observed whales were stranded permanently, demonstrating their ability to perform this behavior expertly despite risks, and 34.4% of their attempts ended with the successful capture of a seal.
On some of occasions, other orcas cooperatively swam behind the beaching orca on either side, likely as a method of preventing prey from escaping in each direction. Other times, both an adult and a juvenile were observed stranding themselves in unison. The adult would fling a seal pup in the direction of the juvenile, who captured it in its mouth. The authors suggest that during these attempts the adult was teaching the juvenile this hunting strategy, similar to New Zealand calves accompanying adults on hunts.
A third, and perhaps most striking, hunting strategy is called wave washing, a strategy for Antarctic orcas hunting seals on ice floes. According to one study, this behavior begins with a group of five to seven orcas cooperatively chipping away at the sides of the floating ice, reducing the diameter of the seal’s refuge and making escape impossible. Additionally, the group often moves the ice into open water, away from adjacent ice floes or debris, in order to increase the likelihood of capture. Once the floe is reduced to a sufficient size, the orcas retreat to a distance of roughly 15 meters then simultaneously swim at full speed towards the ice. At the last moment, the group ducks beneath the ice in order to create a wave to tip the floe. While performing this behavior, groups of orcas are often observed vocalizing at an increased frequency. It has been suggested that these vocalizations may serve to coordinate the group during the attack. If the first attempt is unsuccessful, this behavior is repeated until the seal is washed into the water.
One particularly interesting feature of this strategy is that the orcas do not always immediately kill the seal once it is successfully washed into the water. During several observed wave-washing attacks, a group member captured the seal in its mouth and either released the prey or deposited it onto another ice floe. It is inferred that this unusual behavior may serve as training, social learning, or perhaps as a method of teaching younger group members how to execute this behavior effectively.
Another possible explanation is that wave washing, and perhaps hunting in general, is an element of play for orcas. In other words, hunting is not only a means for finding sustenance, but also for socializing and entertainment. This suggestion is bolstered by observations of multiple unrelated orca populations playing with their prey at length before killing and eating them.
Orcas’ innovative hunting strategies are not limited to the three described above. Orcas around the world are estimated to feed on over 140 species, such as sharks (including great whites), squids, sea otters, dolphins, bony fish, turtles, seabirds, and even baleen whales.
The strategies used to capture this diverse variety of prey are almost ritualistic in nature, and are passed down from generation to generation. In this way, hunting can be considered an integral part of orca culture, with different populations continually recycling their group’s hunting “traditions.”
Photo credit for Three Amazing Orca Hunting Strategies: Animal Galleries.