Weighing up to 90,000 pounds, Gray whales (Eschrichtius robustus) may seem too large to ever worry about being eaten. However, orcas are known to hunt juvenile whales and there have even been reports of groups of orcas attacking adult gray whales. As is common with marine mammals, orcas are very vocal and produce high-pitched “screams” to communicate with one another. Like any loud noise made by a predator, it is possible for their prey to recognize the sound and use it as a cue to actively avoid a potentially dangerous area. Indeed, playback experiments using recorded orca vocalizations have demonstrated that gray whales can localize these orca screams and will leave the area. In contrast, the whales will continue on when random noise, pure tones, or no noise is played at them.

Sketch contributed by Megan McElligott. Fact contributed by Adrian Perez

Sources:

Cummings, W.C. and Thompson, P.O., 1971. Gray whales, Eschrichtius robustus, avoid the underwater sounds of killer whales, Orcinus orca. Fishery Bulletin, 69(3), pp.525-530.

Baldridge, A., 1972. Killer whales attack and eat a gray whale. Journal of Mammalogy, 53(4), pp.898-900.