Полярні ведмеді мають прозору порожнисту шерсть що працює як світловоди для обіг

Polar bears are true masters of the Arctic. Did you know their thick white fur isn’t white at all? It’s actually transparent and hollow, working like tiny fiber optic cables to funnel sunlight to their black skin, which soaks up heat while protecting them from UV rays.
Underneath two layers of fur lies a thick blanket of blubber, keeping them toasty even in frigid temperatures. Their compact ears and tail help conserve heat, while their massive paws—about the width of a ruler—distribute weight on ice and double as paddles in the water.

National Geographic