1. 27.1 Adaptive Value of Behavior KEY CONCEPT Behavior lets organisms respond rapidly and adaptively to their environment.

2. 27.1 Adaptive Value of Behavior Behavioral responses to stimuli may be adaptive. Detecting and responding to stimuli is key to an individual’s survival. Internal stimuli tell an animal what is occurring in its own body. –hunger –thirst –pain

3. 27.1 Adaptive Value of Behavior External stimuli give an animal information about its surroundings. –sound –sight –changes in day length or temperature

4. 27.1 Adaptive Value of Behavior Specialized cells that are sensitive to stimuli detect sensory information. –information is transferred to the nervous system –nervous system may activate other systems in response Animal behaviors help to maintain homeostasis.

5. 27.1 Adaptive Value of Behavior Kinesis and taxis are two types of movement-related behaviors. –Kinesis is an increase in random movement. – Taxis is movement in a particular direction.

6. 27.1 Adaptive Value of Behavior Internal and external stimuli usually interact to trigger specific behaviors. Most behaviors are a response to both internal and external stimuli. External stimuli may trigger internal stimuli. Green anole reproductive behavior is triggered by internal and external stimuli.

7. 27.1 Adaptive Value of Behavior Some behaviors occur in cycles. A circadian rhythm is the daily cycle of activity. –occurs over 24-hour period –run by a biological clock, a combination of melatonin secretions that detect light and different life stages

8. 27.1 Adaptive Value of Behavior Behaviors may occur daily, monthly, seasonally, or annually. –During hibernation, an animal enters a seasonal dormant state.

9. 27.1 Adaptive Value of Behavior Behaviors may occur daily, monthly, seasonally, or annually. –During migration, animals move seasonally from one portion of their range to another. –During hibernation, an animal enters a seasonal dormant state.