Front

Relationship where both species benefit.

Back

mutualism

Front

Dark region in water where photosynthesis doesn't occur; below photic zone.

Back

aphotic zone

Front

A species causing significant community structure change.

Back

keystone species

Front

Succession in an area with remnants of a previous ecosystem, like soil.

Back

secondary succession

Front

First species to colonize barren areas.

Back

pioneer species

Front

Relationship where two organisms live closely together.

Back

symbiosis

Front

A layer of permanently frozen subsoil in the tundra.

Back

permafrost

Front

A relationship where one organism lives on or inside another and harms it.

Back

parasitism

Front

Material from decaying leaves and organic matter.

Back

humus

Front

A plant that sheds its leaves in a season.

Back

deciduous