The proportion of dissolved salts to pure water, usually expressed in parts per thousand (0/00).
A layer of water in which there is a rapid change in temperature with depth.
Mass per unit volume of a substance, usually expressed as grams per cubic centimeter.
A layer of water in which there is a rapid change of density with depth.
An area of the ocean surface with uniform temperatures created by the mixing of water by waves, currents, and tides.
Passively drifting or weakly swimming organisms that cannot move independently of ocean currents; includes microscopic algae, protozoa, jellyfish, and larval forms of many animals.
Algal plankton, which are the most important community of primary producers in the ocean.
Microscopic animals that swim or drift near the surface of aquatic environments.
Organisms that can move independently of ocean currents by swimming or other means of propulsion; includes most adult fish and squid, marine mammals, and marine reptiles.
The forms of marine life that live on or in the ocean bottom; includes marine algae, sea stars, and crabs.
The production of organic matter from inorganic substances through photosynthesis or chemosynthesis.
The process by which plants, algae, and certain prokaryotes use light energy to convert water and carbon dioxide into energy-rich glucose molecules.
The process by which certain microorganisms use chemical energy to produce food.
A nourishment level in a food chain; Plant and algae producers constitute the lowest level, followed by the herbivores and a series of carnivores at progressively higher levels.
A succession of organisms through which food is transferred, starting with primary producers.
A group of interrelated food chains which provides animals with multiple sources of food.