The giant Rorqual whales – which include fin, blue and humpback whales – are capable of ingesting an amount of water higher than the volume of their own body when they get ready to eat. And then they filter out meals of shrimp-like krill and small fish. Now researchers at the University of British Columbia have discovered how they do this as it requires enormous physical distortion.
An accidental discovery while studying ‘lung feeding’ of whales
According to a study published in the journal Current Biology, whales have elastic nerves that help them feed by engulfing huge amounts of water and food. Scientists led by Prof Wayne Vogl had traveled to Iceland to study the “lung feeding” of whales. In humans and other animals, it could cause significant damage to mouth and tongue nerves, which have a fixed length.
Researchers were looking at the muscle in the floor of a whale specimen’s mouth. That when Robert Shadwick, the co-author of the study, found long white cords that were about 3-feet long. They initially thought it was a blood vessel. It could stretch to twice its length and then spring back to its original size. When they cut it open, there was no hollow inside like a blood vessel. Inside the cord, there was a yellowish small core running through the middle.
How these nerves can manage to stretch like bungee cords?
Prof Vogl said this nerve was “very different” from any other nerve he had ever seen. Nerves are brain’s cables that carry messages to all parts of the body. In most animals, it could spell trouble if a nerve gets pulled. But jaw nerves in whales could manage to stretch “like bungee cords.” The microscopic study revealed that nerve fibers in Rorqual whales are wounded tightly into a centralized core.
They “unfold” as the nerve cord stretches. The outside layer is made up of stretchy, tough fibers of elatin protein. Its coating has collagen fibers that can stretch up to a certain point, and are strong enough to prevent the nerves from over-stretching. Evolutionary biologists believe that lung feeding has played a crucial role in allowing whales to grow to their enormous sizes.