1.
abyssal zone: a subdivision of the benthic zone characterized by extremely high pressures, low temperatures, low oxygen, few nutrients, and no sunlight
2.
benthic zone: one of the marine life zones that includes any sea-bottom surface regardless of its distance from shore
3.
benthos: the forms of marine-life that live on or near the ocean bottom; includes marine algae, sea stars, and crabs
4.
chemosynthesis: the process by which certain microorganisms use chemical energy to produce food
5.
density: mass per unit volume, usually expressed as grams per centimeter
6.
food chain: a succession of organisms through which food energy is transferred, starting with primary producers
7.
food web: a group of interrelated food chains
8.
intertidal zone: the area where land and sea meet and overlap; the zone between high and low tides
9.
mixed zone: an area of ocean surface with uniform temperatures created by the mixing of water by waves, currents, and tides
10.
nekton: 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
11.
neritic zone: the marine life zone that extends from the low-tide line out to the shelf break
12.
oceanic zone: the marine-life zone beyond the continental shelf
13.
pelagic zone: open ocean of any depth; animals in this zone swim or float freely
14.
photic zone: the upper part of the ocean into which sunlight penetrates
15.
phytoplankton: algal plankton, which are the nost important community of primary producers in the ocean
16.
phytosynthesis: the process by which plants, algae, and certain prokaryotes use light energy to convert water and carbon dioxide into energy-rich glucose mlecules
17.
plankton: passively drifting or weakly swimming organisms that cannot move independently of ocean currents; includes microscopic algae, protozoa, jellyfish, and larval forms of many animals
18.
primary productivity: the production of organic matter from inorganic substances through photosynthesis or chemosynthesis
19.
pycnocline: a layer of water in which there is a rapid change of density with depth
20.
salinity: the proportion of dissolved salts to pure water, usually expressed in parts per thousands
21.
thermocline: a layer of water in which there is rapid change in temperature with depth
22.
trophic level: a nourishment level in a food chain; plant and algae producers constitute the lowest level, followed by herbivores and a series of carnivores at progressively higher levels
23.
zooplankton: animal plankton
