Big Whales Have Super Stretchy Nerves

This week, researchers from the University of British Columbia published a paper in Current Biology on their serendipitous discovery of the stretching nerve cords of whales.

The team were investigating Rorquals, a family that includes large whales such as the blue, humpback and fin whale. These animals feed using a mechanism known as ‘lunge feeding’, a form of inverted suction feeding in which the whale takes in a huge volume of water and filters it through the baleens.

The researchers were located in Iceland and carried out the analysis on a 20m fin whale. First author, Professor Vogl, emphasised the importance of using the correct equipment when studying the colossal creatures: “if a heart falls on you, it could kill you.”

Whilst investigating adaptations of the whale to lunge feeding, such as specialised muscles and sensory organs in the jaw, the stretching nerve cords were discovered. Robert Shadwick, a co-author of the paper, made the discovery when he noticed a white cord at the mouth base, which he picked up and pulled. At first the team thought it was a blood vessel until it was sliced in half and found not to be hollow, but to contain a small yellow core.

Shadwick described the nerve cords as stretching “like bungee cords”. They have the ability to extend to twice their length and then recoil to their original length. Under the microscope, analysis revealed that the fibres are wound tightly to a central core and unfold as the cable stretches. The cord is coated in coiled collagen fibres which are robust enough to prevent the nerve from overstretching.

Stretching is an unexpected property for nerves as in humans it results in injury. Dr Bewick, a neuroscientist who has studied muscles and nerves for his whole career highlighted how unusual this finding was saying; “one of the things that you really try and avoid – in the clinical situation or just personally – is stretching your nerves.”

The next step for the team is to understand how this stretching nerve functions and additionally if this unusual type of nerve is found anywhere else in the animal kingdom.