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Caught on film for the first time: One of the world’s rarest whales

The first underwater images of True's beaked whales show a cohesive group of three adult or subadult whales swimming together. The species is considered one of the most elusive in the ocean. (Video: Roland Edler, PeerJ, Photo: Dylan Walker/Roland Edler, PeerJ)

Natacha Aguilar de Soto has studied beaked whales for 15 years. She has spent dozens of months at sea, floating above the deepest parts of the ocean, straining her eyes and ears to detect whatever might be moving in the fathoms below.

She rarely finds anything. Beaked whales — a family of 22 cetacean species characterized by dolphinlike noses and missile-shaped bodies — are some of the most elusive animals on Earth. They dive deeper and longer than any other marine mammal and spend an estimated 92 percent of their lives far beneath the ocean surface. One species, the True's beaked whale, is so rare that only a handful of people have ever seen it alive.

“Imagine,” Aguilar de Soto said, “these are animals the size of elephants that we just can't find. They're a mystery.”

Then, in 2013, a colleague sent her a 46-second video clip that had been taken by science students on an educational trip in the Azores. Greenish white shapes drift in a brilliant blue sea. The camera zooms closer and the shapes come into focus: three oblong sea creatures are undulating lazily through the water. They point their pale faces up toward the sky, just barely cresting above the surface, then angle back down again. Too soon, the animals swim out of view, and the videographer pulls the camera back out of the water.

“When I saw the video, I just couldn’t believe it,” said Aguilar de Soto, a marine biologist with the University of St. Andrews in Scotland and the University of La Laguna in the Canary Islands. “I thought, 'My god, these are True's beaked whales.' ”

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The video — the first ever taken of True's beaked whales in the wild — was released Tuesday along with of a detailed new study in the journal PeerJ that aims to demystify the enigmatic animals. The paper combined data from strandings and sightings with genetic analyses of individual whales from both the northern and southern hemispheres. Aguilar de Soto, the lead author, says it's one of the most comprehensive surveys of scientific knowledge about True's beaked whales.

The research could prove vital to efforts to protect the species. Little is known about the appearance and behavior of True's beaked whales and its cousins, making these species difficult to identify even for beaked whale experts. Without an accurate, data-backed methodology for identifying the whales, it's impossible to count them.

“We don’t know how large the populations of True's beaked whale or any other species are,” said Aguilar de Soto. “The populations could decline and we would never know.”

Since the species was identified by Smithsonian scientist Frederick William True in 1913, dead True's beaked whales (Mesoplodon mirus) have been found washed up on beaches across the North Atlantic and South Pacific. Those carcasses are usually bloated and decaying, but they still offer a wealth of information to scientists who have few other means of studying the species.

Research on stranded whales revealed that males have a signature set of small teeth sticking out from their lower jaw, sort of like Sweetums the Muppet. These teeth probably aren't used for eating — like other beaked whales, M. mirus feeds by sucking prey into its mouth — but for fighting with other males.

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Both male and female True's beaked whales are remarkably well-adapted to their deep-sea lifestyle. Their rotund bodies are torpedo shaped, and their sides bear “pockets” into which they can tuck their flippers, making them even more hydrodynamic. They have never been tagged, so scientists don't know how deep they can swim. But if the habits of other beaked whale species are anything to go by, they are certainly champion divers; in 2014, scientists at the Scripps Institute of Oceanography reported that a Cuvier's beaked whale journeyed 9,816 feet below the surface, breaking a marine mammal record. The animals can spend hours underwater on a single breath of air.

Beaked whales are an incredible example of the adaptations of mammals to the ocean,” Aguilar de Soto said. “They overcome incredible physiological challenges to dive, but that means they are very sensitive to anything that changes or challenges the physiological balance.”

Beaked whales like the Trues' live their lives “on a physiological tightrope,” she continued. They must maintain a careful equilibrium within their bodies to withstand the pressure of diving deep. Noise and water pollution, as well as plain old trash, can easily knock them off balance. Scientists have linked mass strandings to the use of military sonar. And last month, a Cuvier's beaked whale washed up on a beach in Norway with 30 plastic bags clogging its stomach.

“We can make the link between what we do on land and on the shores and what happens with this animal offshore,” Aguilar de Soto said. Because of their sensitivity, beaked whales “are like the canary in the coal mine” — warning humans of the threats we pose to creatures that only seem to live in a world apart.

It will take more research and genetic analysis to determine whether True's beaked whales are in danger because of human activity. But Aguilar de Soto said that the PeerJ study is an important first step. It provides scientists with better resources for identifying the species, including the video and analysis of two calves bearing a coloration pattern that has never been seen before. And it indicates possible “hot spots” for True's beaked whales that could be prime locations for researchers hoping to get a better look at the species. Aguilar de Soto said she is interested in searching for the whales around the Azores after seeing the video.

The genetic analyses in the study also suggest that the northern and southern populations — which are separated by a huge swath of ocean — may actually be two distinct species.

“It's just a possibility,” Aguilar de Soto said. She hopes to launch a broader genetic study to investigate.

If the southern beaked whale does turn out to be distinct from the northern one, it would be the fifth new beaked whale species discovered in the past 25 years, Aguilar de Soto said. “That tells us how little we know about this family of elephant-sized mammals that inhabit the oceans.”

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