Imagine gliding smoothly across the surface of the ocean in a beautiful transparent kayak when you come across the tail of a humpback whale perfectly poised above the surface of the water. That is exactly what happened to Brodie Moss when he came across a phenomenon known as "tail sailing".
Whales have all kinds of fun behaviors, from launching themselves out of the sea to carefully planned whale spa visits. This behavior of tail sailing is extremely rare to witness and scientists don’t fully understand the reasons for it. Tail sailing has been observed in southern right whales and humpbacks in multiple locations, so what could be an explanation for this behavior? While Moss doesn't say where the video was filmed, he shared the encounter on his Youtube and Tiktok channels.
Whale tail sailing is often recorded in female whales with calves, so one possible explanation could be that the mothers are resting while the calf swims safely nearby. According to one study, this behavior is not purely for whale nursing, since this can happen in a range of postions, but could allow the mother to rest while feeding.
"We know logically that nursing is a part of this [behavior]," Ed Lyman, resource protection specialist for the Hawaiian Islands Humpback Whale National Marine Sanctuary, told the Huffington Post. When a whale rests in this position, its mammary glands are perfectly oriented to squirt milk into the calf's mouth, he explained.
Some whales are known to sleep in the unusual position of totally upright in the water, so this unusual upright tail behavior could be related to different resting behaviors.
Another alternative explanation for tail sailing is that the whale is simply cooling down. Whales have been known to carry out this behavior for around 15 minutes, though reports suggest it can last many hours. Whale tails contain high levels of blood vessels, which could benefit from evaporative cooling when held above the water.
Whales are known to slap their tails heavily on the surface of the water in a behavior sometimes called “lobtailing”. This could be used as a method of communication between whales, either warning off aggressive males or it is suggested that the noises and subsequent bubbles scare prey species, making them more confused and therefore easier to hunt.