When rorqual whales eat, they open their mouths and lunge. Their tongues invert as their mouths take in a huge volume of water and prey. In the process, nerves running through the ventral groove blubber along the floor of the whales’ mouths stretch to more than double their length and then recoil again without suffering any damage in the process. Now, researchers reporting in Current Biology on February 16 have discovered that the secret to that stretch is not one but two layers of waviness.