A mechanism within an organism (for example, the pineal gland in the human brain) that governs biological rhythms.
The use of sound waves, which are reflected back to the emit ter, as a means of navigating.
A stereotyped, or largely unvarying, behavior that is typical of a par ticular species. An instinctive behavior does not have to be learned; rather, it is fully functional the first time it is per formed.
A small cavity that transmits sound waves, via a network of tiny bones, from the eardrum, which lies between it and the outer ear. Bats use the middle ear to separate transmission and reception signals in echolocation.
A pattern of movement, usually regular and seasonal, whereby animals travel (typically guided by instinct) to specific locations.
The process whereby some organisms thrive and others perish, depending on their degree of adap tation to a particular environment.