11:216:269 Lecture 8: Clocks, Rhythms, Orientation
27 Nov 2017
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Predators: birds can catch bats easily. Birds are diurnal, so bats know that they have to adjust their clock and not be predated upon: ex. crickets. Male crickets sing to attract females; females hide in litter. Males use their clocks to know when to sing/call for female. & caves, only come out at nightfall: synchronize behaviour with events that cannot be observed directly, ex. bees certain times. Bees used clock to visit flowers, only when it opens: declining photoperiods (days are getting shorter) triggers, ex. cicada (generation x - red eyes) - comes out every 17 years rutting, time annual events. Balances both receptors; allows stimulus organisms with 2 receptors to move in a straight line. Turning ; allows animal with 1 receptor to compare 2 stimuli intensities (still travels in a straight line: long distance orientation. Important for migrations: ex. ruby-throated hummingbird, ex. sea turtles. Turning rate is proportional to stimulus intensity.
