Being a baleen feeder isn’t easy. When baleen whales — like the enormous blue whale — gulp up a mouthful of water to filter for food, a pouch of skin under their chins stretches to accommodate the load. This stretch should hurt, but new research finds that whale nerves are specially adapted to prevent these giant beasts from feeling pain.
(From Live Science / By A study of fin whales (Balaenoptera physalus) finds that their nerves have two levels of waviness. The whales’ nerves are coiled like an old-fashioned telephone cord so that they can still work when stretched. Within the coils is a second level of waviness that allows the nerve fibers to twist around the curves without stretching.
“Waviness in nerves per se isn’t surprising, but we saw what appeared to be tight hairpin turns in the tissue that we thought couldn’t be right — nerves shouldn’t be able to bend so tightly,” study leader Margo Lillie, a zoologist at the University of British Columbia in Vancouver, said in a statement.
Lillie and her colleagues from the University fo British Columbia were interested in rorqual whales, a group of baleen whales known for their pleated throats. The pleats allow the whales to take in huge gulps of water, which they then push out of their mouths with their tongues, past their bristle-like baleen. The water gets forced out, while prey gets trapped and swallowed.
In the fin whale, the throat can expand to 162 percent of its resting circumference when feeding, Lillie and her colleagues wrote in the journal Current Biology. That’s a big change for nerves to absorb, so the researchers decided to find out how whale nerves cope.
The researchers dissected fin whale nerves, which are covered with a collagen sheath. Upon opening the collagen sheath, the coiled nature of the nerve was obvious, the researchers reported.
Next, the researchers used a micro-computed tomography (CT) scanner to get a closer look at the nerve structure. Each nerve was actually a bundle of nerve fibers called fascicles, which had their own small-scale waviness, the scientists found. The wavy structure of the fascicles was most apparent on the inside of the larger coils.
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