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| Ecology Notes 2 Section 2-1 |
| Cycles in Time: Rhythms of Life |
| A. Rhythms are patterns that occur over and over again. 1. Biological rhythms are often in harmony with natural cycles of time. a. Biological clocks may be responsible for keeping track of many different cycles of time. b. Biological clocks help living things stay in step with rhythmic cycles of change in their environment. Examples: Birds and butterflys fly south for the winter. Morning glories open and close during the day. c. In nature, biological clocks are very accurate. They set and reset by environmental cues such as dawn or dusk, day length, moisture, and temperature. 2. Daily rhythms are changes that occur daily. a. Diurnal organisms are active during the day. Examples: The emperor tamarin monkey & people. b. Nocturnal organisms are active during the night. Examples: Bats & owls c. Some organisms are neither nocturnal or diurnal like the vole. They are active at dawn and dusk. 3. Lunar rhythms are changes that occur with the moon. a. Some are 12 hour cycles and some are two week cycles. Examples: Grunion (2 week cycle), Rise and fall of tides (12.4 hours) b. Human pregnancy is exactly 10 lunar months from the time the egg is released to the time the baby is born. 4. Annual rhythms are changes that occur annually (yearly), this is usually associated with the seasons of the year. a. Migration is an annual rhythm in which organisms travel from the place where they breed to the place where they feed. b. Hibernation is the winter resting state of animals so they can wait out the cold. c. Estivation is a summer resting state so animals can wait out harsh, hot, and dry conditions. |
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