Baleen whales like this Bryde’s whale need nerves that can stretch Photograph: Rungroj Yongrit/EPA. Baleen whales feed by sucking in vast quantities of water, then filtering the prey from it through modified, comb-like teeth called baleen. In some species of baleen whale, the volume of water engulfed during a lunge can be greater than the volume occupied by the whale itself.
In order to achieve this feat of physical distortion, baleen whales need stretchy nerves. How do we know? Because researchers have taken fin whale nerves (obtained from carcasses at a commercial whaling station in Iceland) and stretched them. “Large nerves that supply the tongue and ventral grooved blubber in fin whales are like bungee cords,” they write in Current Biology this week. “The nerves…can more than double their length without hindering their return to resting length after extension.”
This is unusual. In most vertebrates, nerves are surrounded by a thin collagen wall and overstretching can cause irreparable damage. In the mouths of fin whales, however, the nerves are highly folded at rest. When the whale opens its mouth, the nerves unfold to their full, straightened length, a thick surrounding wall of elastin helping them to recoil into their resting state.
It seems highly likely that other baleen whales, like the blue whale for instance, will have similarly stretchy nerves.