If I were to think of what types of animals hunt in groups, I’d probably say something like wolves, hyenas, lions, maybe even my friend Kevin. That’s why when Season 1, Episode 1 of Frozen Planet depicted killer whales using coordinated and precise hunting techniques, I couldn’t believe my eyes. It turns out that even marine animals take part in “social predation” (or group hunting), something that can be considered one of the greatest boosters of an individual’s ability to survive and have children [1]. One hypothesis is that “social predation” has evolved in multiple populations due to the increase in likelihood of catching the prey [2].
One food source for killer whales is seals, which are often laying on ice sheets. One specific hunting technique used by killer whales is to throw themselves onto the ice sheet to catch the prey [4]. This can be costly; sometimes it can be hard for the whale to return to sea after beaching itself on the ice [4]. So why not bring the food to you?
According to the video, pods of killer whales work together to capture the tasty artic seals that are sitting on the sheets of ice. They do so by swimming as a unit under the ice, and at the exact moment that they are under the seal, they all flip their tail up toward the ice at the same time, breaking the sheet apart. Without that barrier, the seals are sitting ducks. Suddenly, the killer whales have access to their next meal.
But unique group hunting behaviors are not exclusive to only those marine animals with killer in the name. In fact, there are multiple species of fish that do just that. Sailfish for example, take turns swimming through schools of sardines, which injures their prey. This then increases the success of the next sailfish to capture an injured fish [3].
These whales and fish show us just how dependent organisms are on, not only the animals that they eat, but the other individuals that they work with. Teamwork really does make the dream work.
by Robert Roundy
Frozen Planet, Season 1, Episode 1, starting at approximately 34:30
References
- Lang SDJ & DR Farine. 2017. A multidimensional framework for studying social predation strategies. Nature Ecology & Evolution 1(9): 1230-1239.
- Krause J, Herbert-Read JE, Seebacher F, et al. 2017. Injury-mediated decrease in locomotor performance increases predation risk in schooling fish. Philosophical Transactions of the Royal Society B-Biological Sciences 372(1727).
- Herbert-Read JE, Romanczuk P, S Krause, et al. 2016. Proto-cooperation: group hunting sailfish improve hunting success by alternating attacks on grouping prey. Proceedings of the Royal Society B-Biological Sciences 283(1842).
- Guinet C, J Bouvier. 1995. Development of intentional stranding hunting techniques in killer whale (Orcinus orca) calves at Crozet Archipelago. Canadian Journal of Zoology. 73(1): 27-33.
The Evolution of Planet Earth 