Unit 8: Ecology

A taxis is directed movement toward or away from a stimulus (e.g., phototaxis); a kinesis is a change in the rate or turning of movement in response to a stimulus, without a specific direction.

Pill bugs move more and turn more in dry conditions and slow down in humid conditions, so they accumulate in moist places without orienting toward moisture.

Photoperiodism is a physiological response to relative lengths of day and night; for example, flowering in many plants is triggered by night length detected by phytochrome.

Phototropism is growth toward (or away from) light; auxin accumulates on the shaded side of a shoot, elongating those cells so the shoot bends toward light.

Pheromones are chemicals released to communicate with members of the same species, e.g., to attract mates, mark trails (ants), or signal alarm.

A forager's dance conveys the direction of a food source relative to the sun (angle of the waggle run) and its distance (duration of waggling), a tactile and visual signal.