In Animals
Animals that are not diurnal might be nocturnal (active at night) or crepuscular (active primarily during twilight, i.e., at dusk and dawn). Many animal species are diurnal, including many mammals (including humans), insects, reptiles and birds. In some animals, especially insects, external patterns of the environment control the activity (exogenous rhythms, as opposed to patterns inherent in the habitat). Diurnality is descriptive; it refers to an observed 24-hour pattern, as opposed to ~24-hour circadian rhythms which are self-sustaining within the organism.
Some mainly nocturnal or crepuscular animals have been domesticated as pets and have changed into diurnal animals to coincide with the cycle of human life. Examples are pet dogs and cats, which are derived from the wolf and the wild cat, respectively. However, these animals may exhibit their species' original behavior when they are born feral. Other animals have been forced from their normal cycle to an alternate one as a means of avoiding predators, such as beavers becoming nocturnal creatures after extended predation by mankind.
Read more about this topic: Diurnality
Famous quotes containing the word animals:
“The struggle alone pleases us, not the victory. We love to see animals fighting, not the victor raving over the vanquished.... It is the same in gambling, and the same in the search for truth.... We never seek things for themselves—what we seek is the very seeking of things.”
—Blaise Pascal (1623–1662)
“For the time of towns is tolled from the world by funereal chimes, but in nature the universal hours are counted by succeeding tribes of animals and plants, and by growth of joy on joy.”
—Ralph Waldo Emerson (1803–1882)