The True's beaked whale is an enigma. With only a handful of sightings on record, few people have ever even seen it. That's why newly uncovered footage of these rare mammals has generated so much excitement. And the first-of-its-kind video comes from an unexpected source. 

The whale trio was caught on camera by staff with the children's education programme Master Mint during a field cruise all the way back in 2013 – but it wasn't until recently, when the clip made its way into the hands of local experts, that they realised how just lucky they'd been. 

Only seven sightings of a True's beaked whale (Mesoplodon mirus) exist on record for the Macaronesia region (five in the Azores), and the new footage has revealed some interesting traits that might help us to identify these elusive animals better in the future.

Beaked whales regularly dive deep – up to three kilometres (9,816 ft) down – for hours at a time, surfacing for only minutes between dives to gulp air. It's been estimated that these oblong cetacean submarines spend a whopping 92% of their lives submerged. Yet amazingly, the trio in the footage circled around the group's inflatable boat for ten minutes, enough time for a GoPro to be slipped into the water.  

The incredible clip has been included in a new study, which collates sighting data to paint a clearer picture of how these whales use the southernmost reaches of their known habitat. 

"The relative abundance of live sightings of True's beaked whales in deep coastal waters off the Azores, and to some extent off the Canary Islands, suggests that these archipelagos could be ideal areas to research True's beaked whales in the wild," write the authors, led by Natacha Aguilar de Soto, a marine biologist from the University of St Andrews UK and the Canary Islands' Universidad de La Laguna.  

Not only did Aguilar de Soto and the team identify the whales in this video, but they also noticed some distinct colouration in the various sightings that could help us single out the species.

If you look closely, you'll notice a white spot near the animals' heads. This is known as a "blaze" or "beanie cap", and other beaked whales – most notably the Cuvier's beaked whale (Ziphius cavirostris) – have similar features. "These two species are very difficult to distinguish at sea," writes the team. 

However, it turns out the cranial paint job on the True's whale is more pronounced than we thought. Sometimes, for example, the white patch extends down onto the beak or around the eye in this species. 

Learning to properly identify these animals is a big step in getting to know them better – and protecting them. The species has never been tagged, and even the basics are a mystery to us: like where the whales like to hang out, or even how many of them are out there.

The sighting survey also turned up the first close-up images of a True's beaked whale calf, photographed in 2015 by whale-watching charter group Futurismo.

Image: Ida Eriksson/Futurismo

"Both whales showed the pale blaze on their heads," says the team. It's possible that this strip of light skin, which was more pronounced in the youngster, is a feature present only in the region. But with so few sightings to go on, we can't be certain. 

Analysis of confirmed True's whale strandings also showed that this signature skin tone fades quickly after death. This underscores just how easily the whales can be mistaken for their close kin, as well as the importance of genetic sampling as a tool to prevent future mixups.

Almost everything we know about these whales comes from dead specimens, so identifying them accurately during standings is probably our best chance at pinning down population hotspots. 

Based on data from other beaked whale species, scientists suspect that True's whales could be extremely sensitive to environmental disturbances like pollution or noise, but to understand just how human activity might be affecting them, we have to be able to find them first.


Top header image: João Quaresma (Espaço Talassa)/Peer J