Glossary, continued. 



PREDATION — An interspecific interaction where one 

 animal species (predator) feeds on another animal or 

 plant species (prey) while the prey is alive or after killing 

 it. The relationship tends to be positive (increasing) for 

 the predator population and negative (decreasing) for 

 the prey population. See PARASITISM, SYMBIOTIC, 

 CARNIVORE, and TROPHIC LEVEL. 



PRODUCTION — Gross primary production is the 

 amount of light energy converted to chemical energy in 

 the form of organic compounds by autotrophs such as 

 algae. The amount left after respiration is net primary 

 production and is usually expressed as biomass or 

 calories/unit area/unit time. Net production for herbi- 

 vores and carnivores is based on the same concept, 

 except that chemical energy from food, not light, is 

 used and partially stored for life processes. Efficiency 

 of energy transfers between trophic levels may range 

 from 10 to 65%, depending on the organisms and 

 trophic levels. Organisms at high trophic levels have 

 only a fraction of the energy available to them that was 

 stored in plant biomass. After respiration loss, net 

 production goes into growth and reproduction, and 

 some is passed to the next trophic level. See FOOD 

 WEB and TROPHIC LEVEL. 



PROTANDR Y-A type of hermaphroditism in which and 

 individual initially develops as a male, then reverses to 

 function as a female. Common among some species 

 of shrimps. 



PROTISTAN-Pertaining to the eukaryotic unicellular 

 organisms of the kingdom Protista, including such 

 groups as algae, fungi, and protozoans. 



PROTOGYNY — The condition of hermaphrodite plants 

 and animals in which female gametes mature and are 

 shed before maturation of male gametes. 



PROTOZOA — A varied group of either free-living or 

 parasitic unicellular flagellate and amoeboid organ- 

 isms. 



PROTOZOEA — A post-naupliar, pre-zoeal larval stage 

 in penaeid shrimp. See NAUPLIUS and ZOEA. 



PTEROPODS — Group of marine gastropod molluscs 

 with wing-like extensions to the foot, commonly called 

 sea butterflies. 



PYCNOCLINE — A zone of marked water density gra- 

 dient that is usually associated with depth; the density 

 gradient may be due to salinity and/or temperature. 



QUERIMANA — Prejuvenile stage in striped mullet that 

 is identical to the adult form except that it has two anal 

 spines instead of three, that the adipose eyelid is not 

 yet apparent, and that the axillary scales are quite 

 short. 



RACE — An intraspecific group or subpopulation char- 

 acterized by a distinctive combination of physiological, 

 biological, geographical, or ecological traits. 



RADULA — A toothed belt or tongue in the buccal cavity 

 of most molluscs that is used to scrape food particles 

 from a surface, or modified otherwise to serve a variety 

 of feeding habits. 



RANGE— (1 ) The geographic range is the entire area 

 where a species is known to occur or to have occurred 

 (historical range). The range of a species may be 

 continuous, or it may have unoccupied gaps between 

 populations (discontinuous distribution). (2) Some 

 populations, or the entire species, may have different 

 seasonal ranges. These may be overlapping, or they 

 may be widely separated with intervening areas that 

 are at most briefly occupied during passage on rela- 

 tively narrow migration routes. (3) Home range refers 

 to the local area that an individual or group uses for a 

 long period or life. See DISTRIBUTION and TERRI- 

 TORY. 



RECREATIONAL VALUE— Economic and social at- 

 tributes of fishes and invertebrates sought by individual 

 persons as leisure activity. 



RECRUITMENT — The addition of new members to a 

 population or stock through successful reproduction 

 and immigration. 



RED TIDE — A reddish coloration of sea waters caused 

 by a large bloom of red flagellates. The accumulation 

 of metabolic by-products from these organisms is toxic 

 to fish and many other marine species. The accumu- 

 lation of these metabolites in shellfish makes shellfish 

 toxic to humans. 



PUERULUS — A brief (several weeks), nonfeeding, 

 oceanic postlarval phase in the development of spiny 

 lobster. 



350 



