cachalot

noun

1. The sperm whale, Physeter macrocephalus.

   “A flexible rib cage facilitates the collapse of the lungs of a diving cachalot (a synonym derived from an old French word for tooth), so reducing the nitrogen uptake which is responsible for decompression sickness in diving humans, while high levels of haemoglobin in the blood and myoglobin in the skeletal muscles carry the oxygen required to sustain long periods between breaths.”