Moment giant fin whale's huge mouth engulfs thousands of gallons of water

This is the moment the planet's second largest living creature opens its giant jaws and swallows thousands of gallons of water during feeding.

The fin whale was filmed by videographer Rhys Morgan off the Pembrokeshire coast in Wales, and it shows the mammal's expandable pleats take in up to 18,000 gallons of water and krill.

Morgan said "it was complete luck" that he captured the whale feeding and swimming with dolphins on his drone while fishing with a friend.

Second only to the blue whale, the fin whale is one of the largest animals ever to have lived, reaching up to 24m in length and weighing up to 70 tonnes.

Despite its enormous size, the fast-swimming creature is elusive and spends much of its life in the open ocean and often surfacing only briefly before disappearing beneath the waves.

The mammal can be found all over the world's oceans but is most at home in cooler waters.

Morgan, from Houghton, Pembrokeshire, works at an oil refinery by day, and said he was "brought up on the water", but became interested in marine videography after using his friends drone to capture footage of sea creatures across the surface of the ocean.

"It's pretty incredible really," Morgan said.

"It makes you feel very small out there."

To avoid causing harm to the whales while recording out at sea, Morgan said: "We do what we can to keep our distance in the boat but unfortunately nature can have a mind of its own sometimes.

"There's been times when we've been anchored up fishing with nothing happening in the area and a whale has popped up next to us.

"The wildlife will approach you sometimes."

Dr Marianna Chimienti is a lecturer in marine top predator ecology at Bangor University and said Morgan experienced a "rare and fortunate encounter".

Chimienti, who specialises in animal behaviour added: "It is normal that the fin whale comes and feeds at the surface, as it is part of the species foraging strategy but being in the coastal water is quite spectacular.

"In theory, they should have migrated."

Little is known about fin whale migration but their movements are believed to be quite different from other baleen whales such as blues and humpbacks.

Scientists have found that fin whales are more abundant in higher latitudes in warmer months of the year, and more numerous in lower latitudes during colder months, but this can vary.

Fin whales have a pretty simple diet which is usually made up of krill, small schooling fish and squid.

Due to the small size of its prey, fin whales have to eat a lot to survive and can spend several hours each day feeding, consuming up to 2,000 kilograms of food.