Wash Zone: The depth zone in which sediments are disturbed by wave action near the shoreline.

Wastewater: Water used in domestic or industrial process and as a result contains pollution that has potentially harmful substances.

Water Mass: A body of water that maintains its identity and can be characterized by such parameters as temperature and salinity.

Water Properties: Elements used to determine water quality. Total hardness, carbonate hardness, pH, ammonia, nitrate and temperature are the most used indicators.

Water Table: The upper level of a saturated formation where the water is at atmospheric pressure. The water table is the upper surface of an unconfined aquifer.

Watershed: The land area that is drained by a river or estuary and its tributaries. Watersheds range in size from a few acres to large areas of the country.

Wave Maker: A device which switches powerheads on and off at timed or random intervals, in order to simulate wave action in an aquarium.

Weber's Apparatus: Described in 1820 by E. H. Weber, the Weber's apparatus connects the hearing organ with the swim bladder where it operates as a sounding board thus amplifying sounds.

Weir: A fence-like fish trap placed across a stream or outlet forces fish to swim into waiting traps.

Westerlies: Persistent eastward-equatorward winds in midlatitudes in both the Northern and Southern Hemispheres.

Wet/Dry Filter: A biological filtration system that consists of a plastic chamber with a biological filtration media. Water runs through the media, which mixes with the air, and reacts with the bacteria, which serve to remove ammonia and nitrites. It is this wet / dry exchange that promotes bacterial growth. Common forms are trickle filters and rotating "paddle wheel" filters.

Whiteworms: A small worm used as food available either live or freeze-dried.

Whorl: A group of more than two organs of the same kind, like leaves arising at the same level. Also refers to each turn of a spiral shell.

Windward Side: The side of an island that faces a persistent wind.

Wing Pad: A developing wing or sheath of a developing wing.

Within-Habitat Comparison: A contrast of diversity between two localities of similar habitat type.

Wrack Zone. A bank of accumulated litter at the strandline.