Drone films fin whale swallowing up to 18,000 gallons in a single gulp

A drone has filmed a fin whale opening its enormous mouth and taking in thousands of gallons of water in a single gulp. The footage was shot off the Pembrokeshire coast in Wales and shows the animal feeding right at the surface, with dolphins swimming nearby.

The mouth that can stretch to 18,000 gallons

The fin whale is the second largest living creature on the planet, after the blue whale, and one of the largest animals ever to have lived. It can reach 24m (79ft) in length and weigh up to 70 tonnes. What the drone caught was not a bite in the everyday sense: the whale opens its jaws and the expandable pleats in its mouth take in up to 18,000 gallons of water and krill in one go.

The water arrives with food in it. Fin whales live mostly on krill, small schooling fish and squid, and because the prey is so small the animal has to eat a great deal of it. They can spend several hours of the day feeding and put away up to 2,000 kilograms of food.

Complete luck over the water

The footage was taken by videographer Rhys Morgan, who is from Houghton in Pembrokeshire and works at an oil refinery by day. He said he was brought up on the water and became interested in marine videography after using a friend's drone to film sea creatures at the surface.

He was out fishing with a friend when the whale appeared, and he said it was complete luck that he captured it feeding and swimming with dolphins. "It's pretty incredible really," he said. "It makes you feel very small out there."

Morgan also said the people in the boat do what they can to keep their distance. "We do what we can to keep our distance in the boat but unfortunately nature can have a mind of its own sometimes," he said. He described times when they had been anchored up and fishing with nothing happening nearby, only for a whale to pop up next to them. "The wildlife will approach you sometimes."

A whale that, in theory, should have moved on

Dr Marianna Chimienti, a lecturer in marine top predator ecology at Bangor University, called it a "rare and fortunate encounter". She said it is normal for a fin whale to come and feed at the surface, since that is part of how the species hunts, but that being in coastal water is quite spectacular.

Her most striking point was about timing: "In theory, they should have migrated."

Little is known about fin whale migration, and their movements are believed to be quite different from those of other baleen whales such as blues and humpbacks. Scientists have found that fin whales are more abundant in higher latitudes in the warmer months and more numerous in lower latitudes in the colder months, though this can vary.

That is part of why the clip stands out. Fin whales are elusive for their size: they swim fast, spend much of their lives in the open ocean and often surface only briefly before disappearing beneath the waves. They are found in oceans around the world but are most at home in cooler waters.