Adaptations to Various Modes of Life
The earth’s revolution on its axis around the sun results in a 24-hour cycle composed of light (day) and darkness (night) with twilight (dawn and dusk) periods between. The lengths of these periods vary with season and latitude. Within the tropics, especially along the equator, there is practically no variation in the photoperiod (a constant light/dark period of approximately 12 hours each throughout the year) while in the polar regions there can be days in summer that are composed of 24 hours of daylight. Semi-tropical and temperate regions exhibit variations which are intermediate of the two extremes.
KeywordsVisual Pigment Chromatic Aberration Visual Cell Nocturnal Species Yellow Filter
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