Discuss the effect of light on animals.

Explanation

1. Pigmentation. Animals develop dark colour in dim light and light colour in bright light. Prolonged exposure to light in humans causes tanning of skin.
2. Aphids develop wings in response to alternate light and darkness.
3. Daily Rhythm in animals. Many animals are (i) duirnal (active during the day e.g., Butterflies, birds), (ii) Some Nocturnal e.g. Cockroach, Bats, some are (iii) Auroral (active during dusk or sunset) e.s., Rabbit or (iv) Crepuscular (Active during dawn and dusk).
4. Animal breeding.Turkeys, breed in response to lengthening of days, white sheep, goat, deer et.c breed in response to shortening of days.