Zoologist Robert T. Paine, who coined the term "keystone species," had an unorthodox way of doing his work. Instead of just observing the habitat of the Pisaster ochraceus sea star, Paine experimented by actually changing the habitat. Paine and his students from the University of Washington spent 25 years removing the sea stars from a tidal area on the coast of Tatoosh Island, Washington, in order to see what happened when they were gone. He was one of the first scientists in his field to experiment in nature in this manner.
characterized by the absence of life or living organisms
in large amounts.
tree or shrub that is often thorny.
harmful chemicals in the atmosphere.
(singular: alga) diverse group of aquatic organisms, the largest of which are seaweeds.
organism that changes biotic and/or abiotic resources from one physical state to another.
caused by people.
species at the top of the food chain, with no predators of its own. Also called an alpha predator or top predator.
region at Earth's extreme north, encompassed by the Arctic Circle.
organism that modifies its environment by modifying its own biology.
a slope of land adjoining a body of water, or a large elevated area of the sea floor.
body of water partially surrounded by land, usually with a wide mouth to a larger body of water.
having to do with the bottom of a deep body of water.
all the different kinds of living organisms within a given area.
the process in which a living organism wears away at rock or another hard substance.
study of living things.
area of the planet which can be classified according to the plant and animal life in it.
having to do with living or once-living organisms.
type of animal (mollusk) with two shells hinged together, such as a clam or mussel.
land covered by evergreen trees in cool, northern latitudes. Also called taiga.
ecological phenomenon in which a producer or primary consumer is removed from the environment.
small hole or tunnel used for shelter.
reproduction of rare species controlled by humans in a closed environment, such as a zoo.
to stop or end.
large animals with popular appeal due to their appearance or cultural significance.
gradual changes in all the interconnected weather elements on our planet.
to fall apart completely.
group of one species of organism living close together.
to merge or fuse into one entity.
management of a natural resource to prevent exploitation, destruction, or neglect.
rocky ocean features made up of millions of coral skeletons.
type of animal (an arthropod) with a hard shell and segmented body that usually lives in the water.
learned behavior of people, including their languages, belief systems, social structures, institutions, and material goods.
structure built across a river or other waterway to control the flow of water.
to name or single out.
foods eaten by a specific group of people or other organisms.
spread of something to a new area.
the way something is spread out over an area.
having to do with money.
community and interactions of living and nonliving things in an area.
organism that creates, modifies, maintains or destroys a habitat.
organism threatened with extinction.
conditions that surround and influence an organism or community.
to destroy or remove.
mouth of a river where the river's current meets the sea's tide.
the hard external shell or covering of some animals.
methods by which an organism obtains food and eats.
aquatic animal that strains nutrients from water.
industry or occupation of harvesting fish, either in the wild or through aquaculture.
organism that serves as a symbol for an environmental habitat, movement, campaign, or issue.
all related food chains in an ecosystem. Also called a food cycle.
(singular: foraminifer.) Type of microscopic organism (protist) that forms a shell and lives in marine or salty conditions.
ecosystem filled with trees and underbrush.
species that creates or maintains an ecosystem.
characteristic of species whose contributions to an ecosystem are matched by other species.
movement and exchange of genes between interbreeding populations.
heat energy generated within the Earth.
system or order of a nation, state, or other political unit.
ecosystem with large, flat areas of grasses.
animal that feeds on grasses, trees, and shrubs.
environment where an organism lives throughout the year or for shorter periods of time.
organism that eats mainly plants and other producers.
group of animals.
the study of the way human communities and systems interact with their environment.
organism that is very sensitive to changes in its environment. Also called a sentinel species.
characteristic to or of a specific place.
to slow or prevent.
a species that does not naturally occur in an area. Also called alien, exotic, or non-native species.
type of plant or animal that is not indigenous to a particular area and causes economic or environmental harm.
animal that is no longer a baby but has not reached sexual maturity.
organisms that participate in mutually beneficial interactions, the loss of which would have a profound impact on the ecosystem.
organism that has a major influence on the way its ecosystem works.
animals raised for sale and profit.
animal with hair that gives birth to live offspring. Female mammals produce milk to feed their offspring.
having to do with the ocean.
animal, person, or thing representing a group of people or organization.
wide area of grassland.
organisms that travel from one place to another at predictable times of the year.
to change or alter.
large phylum of invertebrate animal, all possessing a mantle with a significant cavity used for breathing and excretion, a radula (except for bivalves), and the structure of the nervous system.
species that occur naturally in an area or habitat. Also called indigenous species.
sweet plant material that attracts pollinators.
protected area built by birds to hatch their eggs and raise their young.
role and space of a species within an ecosystem.
substance an organism needs for energy, growth, and life.
process of too many animals feeding on one area of pasture or grassland.
large plateau in southern South America, stretching from the Andes Mountains to the Atlantic Ocean.
study of the natural features and processes of the Earth.
flat, smooth area at a low elevation.
(singular: plankton) microscopic aquatic organisms.
organism that produces its own food through photosynthesis and whose cells have walls.
to transfer pollen from one part of a flower (the anther) to another (the stigma).
animal, object, or force such as wind that transfers pollen from one plant to another, allowing seeds to develop.
chemical or other substance that harms a natural resource.
a type of animal with a fixed base, a tubelike body, and tentacles for catching prey.
total number of people or organisms in a particular area.
animal that hunts other animals for food.
animal that is hunted and eaten by other animals.
organism that eats plants or other autotrophs.
organism on the food chain that can produce its own energy and nutrients. Also called an autotroph.
highest-ranking teacher at a college or university.
to strike violently and repeatedly.
a ridge of rocks, coral, or sand rising from the ocean floor all the way to or near the ocean's surface.
available supply of materials, goods, or services. Resources can be natural or human.
to wander or travel over a wide area without a specific destination.
type of tropical grassland with scattered trees.
organism that eats dead or rotting biomass, such as animal flesh or plant material.
solid material transported and deposited by water, ice, and wind.
structure that protects people or other organisms from weather and other dangers.
type of plant, smaller than a tree but having woody branches.
having to do with a community or other group of organized people.
top layer of the Earth's surface where plants can grow.
native, geographic area in which an organism can be found. Range also refers to the geographic distribution of a particular species.
region just south of the Arctic Circle.
something used to represent something else.
land an animal, human, or government protects from intruders.
to develop and be successful.
large, flat area where mud and sediment are deposited by ocean tides. Also called tidal flat or mudflat.
wood in an unfinished form, either trees or logs.
ecological phenomenon in which a top predator is removed from the environment.
person who travels for pleasure.
ecological phenomenon triggered by the addition or removal of predators from an environment.
large, usually migratory species on which other species in an ecosystem depend.
to tear or remove a tree or other plant by the roots.
introduction of harmful materials into a body of water.
area of land covered by shallow water or saturated by water.
land covered with trees, usually less dense than a forest.
the study of animals.