ear structures on the sides of their heads and highly evolved hearing mechanisms beneath that. Their chief conduit for hearing is their lower jaw. The lower jaws of cetaceans are not only fairly large, but they are also hollow, filled with a fatty material that collects sound and transmits it through the middle and inner ears and on to the auditory nerve. This structure means that not only are the most distant and subtle sounds detected, but all these sounds are processed by those big brains at lightning speed,
