Scientists from the University of British Columbia (UBC) have discovered a large piece of nerve which they believe holds the key to explaining how rorqual whales feed using their gigantic mouths.

Professor Robert Shadwick, head of UBC's zoology department, led a team of researchers who studied the remains of a fin whale, considered to be the second largest animal in the world.

While the team initially though that the piece of whale nerve was a blood vessel, they found out that it had a yellowish central core with a thick white coating.

"It was then that we realized it must be a nerve, unlike anything we had seen before," Professor Wayne Vogl of the Department of Cellular and Physiological Sciences at UBC said.

Vogl explained that the nerves located on the floor of the rorqual whale's mouth are unusually expandable similar to bungee cords. He said that this is an interesting discovery since most nerves of vertebrates have fixed lengths.

Rorqual whales-humpbacks, fins, blues, minkes and their close relatives-feed on small crustaceans called krill. These giant whales swallow krill by the millions using a method called lunge-feeding, wherein they quickly swim toward a school of krill then they open their mouth to take in their food.

In order to allow the whale to take in more food, two bones located on its lower jaw swing outward while its tongue moves inward. The mouth of the whale also balloons to massive proportions, capable of increasing its size by up to 162 percent.

The research team, however, noted that the whale's nerve fibers do not stretch during feeding. These fibers instead fold and unfold instead each time the animal lunge-feeds.

Vogl said the nerves of rorqual whales get hurt or injured every time they stretch.

Scientists have also recorded other animals with wide openings for their mouths.

The bowhead whale currently holds the Guinness Record for having the biggest mouth in the animal kingdom, which can measure up to 16 feet long, 12 feet high and 8 feet wide. As one of the species of baleen whales, this whale has the largest baleen, or filter-feeding organ, consisting of 325-360 fringed plates that overlap located on both sides of its upper jaw.

Perhaps one of the most popular big-mouthed animals on the planet is the megamouth shark. First caught in 1976 off the coast of Kāneʻohe in Hawaii, this rare 18-foot shark has a mouth of up to 4 feet and 3 inches in width.

Despite its imposing name, this megamouth shark is known to be a planktivorous, an aquatic animal that feeds on tiny organisms called plankton.

Photo: A.Davey | Flickr