Endotherms
Animals that generate their own body heat through metabolism.
Ectotherms
Animals that lack an internal mechanism to control body temperature.
Instinct
Inborn, unlearned behavior.
Learning
A change in behavior brought about by an experience.
Imprinting
When offspring accept the first moving object they see as their mother in the absence of their actual mother.
Critical period
A window of time when the animal is sensitive to certain aspects of the environment during imprinting.
Habituation
When an animal learns not to respond to a stimulus.
Circadian rhythms
Internal clocks or cycles that occur in animals and plants.
Pheromones
Chemical signals between members of the same species that affect behavior.
Agonistic behavior
Aggressive behavior that occurs due to competition for resources.
Dominance hierarchies
A social structure in which members of a group establish the most dominant members.
Territoriality
A behavior that occurs when food and nesting sites are scarce.
Altruistic behavior
Unselfish behavior that benefits another organism in the group at the individual's expense.
Mutualism
A symbiotic relationship in which both organisms benefit.
Commensalism
A symbiotic relationship in which one organism benefits without harming the other.
Parasitism
A symbiotic relationship in which one organism harms the other.
Tropism
A turning in response to a stimulus
Phototropism
The way plants respond to sunlight
Gravitropism
The way plants respond to gravity
Thigmotropism
The way plants respond to touch
Ecology
The study of interactions between living things and their environments
Biosphere
The entire part of the Earth where living things exist
Ecosystem
The interaction of living and nonliving things
Community
A group of populations interacting in the same area
Population
A group of individuals that belong to the same species and that are interbreeding.
Gross Productivity
The total amount of organic matter produced by photosynthesis in an ecosystem.
Net Productivity
The amount of organic matter produced by photosynthesis in an ecosystem, minus the amount used by the producers for their own cellular energy needs.
Keystone Species
A species that has a disproportionately large impact on its ecosystem relative to its abundance.
10% Rule
Only about 10% of the energy available at one trophic level is transferred to the next level.
Biomass Pyramid
A diagram that shows the amount of living organic matter at each trophic level in an ecosystem.
Pyramid of Numbers
A diagram that shows the number of individual organisms at each trophic level in an ecosystem.
Pyramid of Energy
A diagram that shows the amount of energy available at each trophic level in an ecosystem.
Toxins
Harmful substances that can accumulate in the tissues of organisms.
Concentration
The process by which toxins become more concentrated in the tissues of organisms at higher trophic levels.
Danger
The increased risk of harm to animals at higher trophic levels due to the concentration of toxins in their tissues.
Ecological succession
The predictable procession of plant communities over a relatively short period of time (decades or centuries).