organism

an individual living thing, such as a bacterium, fungus, protist, plant, or animal

population

a group of interacting individuals belonging to one species and living in the same geographic area

community

an assemblage of all the organisms living together and potentially interacting in a particular area

abiotic component

a nonliving component of an ecosystem, such as air, water, or temperature

biotic component

a living component of a biological community; an organism, or a factor pertaining to one or more organisms

biosphere

the entire portion of Earth inhabited by life; the sum of all the planet's ecosystems

habitat

a place where an organism lives; an environmental situation in which an organism lives

tropics

latitudes between 23.5 degrees north and south

doldrums

an area of calm or very light winds near the equator, caused by rising warm air

trade winds

the movement of air in the tropics

temperate zones

latitudes between the tropics and the Artic Circle in the north and the Antartic Circle in the south; regions with milder climates than the tropics or polar regions

prevailing winds

winds that result from the combined effects of Earth's rotation and the rising and falling of air masses

westerlies

winds that blow from east to west

biome

a terrestrial ecosystem, largely determined by climate, usually classified according to the predominant vegetation and charcterized by organisms adapted to the particular environments

intertidal zone

a shallow zone where the waters of an estuary or ocean meet land

pelagic zone

the region of an ocean occupied by seawater

phytoplankton

algae and photosynthetic bacteria that drift passively in aquatic environments

zooplankton

animals that drift in aquatic environments

benthic zone

a seafloor, or the bottom of a freshwater lake, pond, river, or stream

photic zone

the region of an aquatic ecosystem into which light penetrates and where photosynthesis occurs

aphotic zone

the region of an aquatic ecosystem beneath the photic zone, where light does not penetrate enough for photosynthesis to take place

continental shelf

the submerged part of a continent

coral reef

a warm-water, tropical ecosystem dominated by the hard skeletal structures secreted primarily by the resident cnidarians

estuary

an area where fresh water merges with sea water

wetland

an ecosystem intermediate between an aquatic ecosystem and a terrrestrial ecosystem. Wetland soil is saturated with water permanently or periodically

savanna

a biome dominated by grasses and scattered trees

desertification

the conversion of semi-arid regions to desert

chaparral

a biome dominated by spiny evergreen shrubs adapted to periodic drought and fires; found where cold ocean currants circulate offshore, creating mild, rainy winters and long, hot, dry summers

temperate grassland

a grassland region maintained by seasonal drought, occasional fires, and grazing large mammals

temperate broadleaf forest

a biome located throughout midaltitude regions where there is sufficient moisture to support the growth of large, broadleaf deciduous trees

coniferous forest

a biome characterized by conifers, cone-bearing evergreen trees

tundra

a biome at the northernmost limits of plant growth and at high altitudes, characterized by dwarf woody shrubs, grasses, mosses, and lichens

permafrost

continuously frozen ground found in the tundra