A Humpback Whale (Megaptera novaeangliae) calf breaches (pictures courtesy of Lorenzo Fiori).
Last sunday our guests witnessed the jaw-dropping moment everyone has always been waiting for: a whale breaching.
Breaching is a jump where at least 40% of a whale’s body leaves the water.
The main reason for this aerial behaviour appears to be sociality. Animals found in larger groups, and for whom social structure seems more important, breach more frequently. So we may believe that breaching has a communicative function.
What might the breacher be signaling? Suggestions for large whales include aggression, “extreme annoyance” (perhaps with a nearby vessel), an “act of defiance”, courtship, or a display of strenght by males. For dolphins, leaps have mainly been considered signals concerning schooling. Leaps may be used to define the deployment of a school, to recruit dolphins to a cooperative feeding event or as social bonding.
One proposed benefit of breaching is the removal of ectoparasites. For example, we can imagine that whale lice can be really annoying when crawling on whale’s bodies (if you wish more information about these crustaceans, check our previous post by clicking here). As cetaceans don’t have the ability to scratch, breaching could be relieving.
A North Atlantic Right Whale (Eubalaena glacialis) calf’s head and mouth is covered by orange whale lice. Whale calves are fastly colonized by whale lice aggregating around the genital slit of their mothers.
References:
Würsig B., Thewissen J.G.M., Kovacs K. M. 2018. Encyclopedia of Marine Mammals, third edition. pp. 6-9
