[WATCH] Risso's Dolphin Performs Unusual Headstand Underwater While Rotating Slowly

Drone footage used in surveying marine mammals off the Isle of Lewis in Scotland showed a Risso's dolphin suspended vertically with its nose down, completely submerged underwater, and rotating slowly.

Wildlife conservationists said that this unusual behavior of headstanding was previously seen in other species of dolphin in other parts of the world with their tails out of the water, but this was the first time they have seen a fully-submerged dolphin doing the maneuver.

[WATCH] Why Was a Risso's Dolphin Performing an Unusual Headstand Underwater and Rotating Slowly? Pixabay/Ildigo

Why Was the Dolphin Doing a Headstand-Like Maneuver?

Whale and Dolphin Conservation (WDC) has been monitoring the population of Risso's dolphins off the coast of the Isle of Lewis by taking pictures of their dorsal fins with unique characteristics like fingerprints. The charity has been using non-invasive surveying techniques to study the dolphins and recording them individually from boats at a distance.

They have used a drone as part of that effort this year, Mail Online reported. This helped them capture the never-before-seen underwater headstanding behavior of a Risso's dolphin that is thought to be at least 20 years. The dolphin was on its own when they captured the footage of the unique behavior.

WDC researcher Nicola Hodgins, a policy manager in the charity, said that they did not know why the dolphin was behaving in that way, but perhaps it could have been communicating with other dolphins and creatures underwater. She added that this shows how little is known about marine mammals' social and cultural lives.

Studying their behavior will help wildlife conservation understand the species' needs and requirements to protect them better and their habitats. Hodgins noted that this was the first time they saw this behavior and added that maybe it was just the dolphin's way to chill and relax.

Risso dolphins have been recorded before doing "headstanding" before, especially in the Mediterranean region. But in those cases, their body is always half in and half out. Their bodies are submerged underwater, while their tails are out of the water. Watch this unique behavior below the article.

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Risso Dolphins Invented Rapid Spin-Dive Technique to Drill Into the Water

The charity is excited to find out why the dolphins are headstanding and piece it together with the dolphin's other unique behavior. An earlier article by New Scientist reported that scientists have noticed that Risso's dolphins dive rapidly to efficiently catch their prey that is hundreds of meters deep underwater.

The round-faced dolphins would exhale air in their lungs and dive at high speeds on a near-vertical trajectory, making at least three twists to "drill" through the water. Scientists call this move the spin dive, a technique that helps Risso's dolphins easily get to a dense layer of water full of squid, crustaceans, and fish to make their dives highly profitable.

Furthermore, scientists noted that the dolphins would start an intense stroke of the fins that rotated their bodies when making deeper dives. They combine it with a strong exhalation that scientists presume reduces their buoyancy.

Then they turn downward at a 60-degree angle and enter a high-speed, twisting descent followed by a gliding phase to achieve a speed of 5.5mph (9kph) and reach an estimated depth of 1,397 feet (426 meters). They start using echolocation to find their prey in the dark when they finish spinning, which is 36 seconds into their dive.

This behavior suggests that dolphins carefully plan the dive, knowing that there is food in that layer of the ocean waters. Risso's dolphins would stay underwater for almost 10 minutes, including the diving behavior.