VIDEO: Watch a humpback whale do a headstand

Screenshot. Photo: Hawaii Public Radio/ YouTube.

Scientists have captured an incredibly rare sight of a humpback whale doing a “headstand” off the coast of Hawaii.

It was captured by a research drone by the Office of National Marine Sanctuaries’ Collaborative Center for Unmanned Technologies during a field operation earlier last week.

In it a female humpback whale can be seen swimming vertically and doing a “headstand and drifting with her tail out of the water” while its calf swims around.

The scientific name for the behaviour is “tail-sailing” and is common for southern right whales but has “rarely been observed or documented among humpbacks,” according to the National Oceanic & Atmospheric Administration.

“We’re not entirely sure why the whales do this,” said Ed Lyman, a resource protection specialist for Hawaiian Islands Humpback Whale National Marine Sanctuary.

“But we think this could be another way for them to rest, nurse, or just try to stay cool.”

Check it out below.