phylogeny: the evolutionary background for the development of a trait or behavior in an animal.

ontogeny: the processes by which a trait or behavior develops in an animal.

mechanism: the way in which the animal is able to achieve a trait or behavior.

adaptive value: the way in which a trait or behavior positively affects the animals survival likelihood.

convergent evolution: the same trait or behavior evolving independently in two or more species.Animation of the Luciferin system at work!

Luciferin: A pigment that reacts with oxygen via the enzyme luciferase to emit energy in the form of light.

sympathetic nervous system: an involuntary aspect of the nervous system associated with stress or arousal responses ("fight or flight").