Jumping whales use their bodies for percussion-based communications
If you’re a 72,000 pound whale moving around 18 miles-per-hour in order to launch your body as high as 10 feet above sea level, you don’t do it by accident. The amount of energy demanded to pull off such a feat makes this an impractical activity to spend your efforts on unless there’s some other advantage of doing so. Granted, YouTube provides many counter examples of humans doing things for no discernible benefit to themselves or others, but the frequency and consistence of jumping whales like the humpback may finally be revealing why they are willing to put so much effort into these activities, even at times when they’re eating fewer calories than normal.
Scientists in Australia first started isolating this pattern after watching 76 groups of humpback whales (Megaptera novaeangliae) for over 200 hours. They looked at more than just breaching, or jumping, whales, and also looked for other behaviors that took place on the surface of the ocean, like slapping fins and flukes on the water. What they found is that these activities seemed to correspond to the proximity of the active whale’s audience. If it was close to its listeners, slapped fins seemed to suffice. If the whale was interested in peers over two and a half miles away, full-body breaches were more likely to be used.
Slapping and breaching as talking and shouting
The core of all this is whales’ dependence on audio communication. Humpback whales are noted for their elaborate vocalizations that seem to be tied to courting mates, and they clearly have an appreciation for communicating through sound. Part of this specialization is thanks to the fact that sound carries much further through water than light does, and so it’s a more dependable way to carry on longer-distance conversations. While blue whales’ deep vocalizations may be detectable for miles, even whales sometimes need a way to pipe up over other background noises. Researchers suspect that that’s when they start relying on forms of percussion to get each other’s attention.
In this model, the slaps are quieter, and thus useful for communicating with immediate neighbors, parents or calves. When a whale then wants to greet or acknowledge another group of whales moving in from a distance, a breach becomes useful since the much louder sound will carry over a bigger distance, or at least over other sound in the area. Researchers noted that on windier days, whales were more likely to resort to breaching than normal, indicating that they were having to compete with more background noise in order to be heard.
Beyond helping us better understand this amazing and at times dramatic behavior, it also reinforces the notion that humans must be more conscientious about the noise we create in the oceans. There are many reasons to be concerned about the increasing noise levels underwater, and now we can add shouting humpbacks to that list.
Source: https://www.hakaimagazine.com/article-short/why-whales-leap-air by Jason G. Goldman, Hakai Magazine
