Blue whales are the largest animals on Earth, but we know surprisingly little about their complex social interactions—and they've rarely been recorded on camera.

But new footage filmed off the coast of Sri Lanka by pro whale photographer Patrick Dykstra, in conjunction with blue whale independent researcher Howard Martenstyn, claims to be a first. Their video shows what they believe is the first known clip of a blue whale "heat run" but has drawn criticism from established blue whale researchers.

Heat runs have been well documented in humpback whales, but no known footage exists of the behavior in blue whales (or at least that Dykstra or National Geographic could find).

A BBC Earth clip from 2009 shows a heat run