Definition: A species that can greatly affect population numbers of an ecosystem
Example: Sea otters are keystone species, because without them, the health of their ecosystem would greatly decline. Sea otters eat sea urchins, which consume kelp, which act as a habitat for fish. Without sea otters, the sea urchin number would rise, causing kelp biomass to decrease, causing any fish populations that use kelp as a habitat to decrease also.
- Keystone species are much less common than dominant species but still extremely important to the health of an ecosystem
- Keystone species are generally not abundant
- Keystone species can be plants or animals