Glossary, continued. 



HATCHERY-REARED— Distinguished from naturally- 

 occurring recruits in population, these animals are 

 raised in captivity for the purposes of release or har- 

 vest. 



HERBIVORE— An animal that feeds on plants (phy- 

 toplankton, large algae, or higher plants). 



HERMAPHRODITIC— Refers to an organism having 

 both male and female sex organs on the same indi- 

 vidual. 



HETEROTROPH-An organism (e.g. animals and fungi) 

 which obtains nourishment by consuming exogenous 

 organic matter. Compare to AUTOTROPH and 

 PHOTOTROPH. 



ISOBATH — A contour mapping line that indicates a 

 specified constant depth. 



ISOPODA— An order of about 4,000 species of dor- 

 soventrally compressed crustaceans that have ab- 

 dominal gills and similar abdominal and thoracic seg- 

 ments. Terrestrial pillbugs and thousands of benthic 

 marine species are included. Most species are scav- 

 engers and/or omnivores; a few are parasitic. 



ISOTHERM — A contourline connecting points of equal 

 mean temperature for a given sampling period. 



ITEROPAROUS— Refers to an organism that repro- 

 duces several times during its lifespan (i.e., does not 

 die after spawning); compare with SEMELPAROUS. 



HYDROZOA— A class of the phylum Cnidaria. The 

 primary life stage is nonmotile and has a sac-like body 

 composed of two layers of cells and a mouth that opens 

 directly into the body cavity. A second life stage, the 

 free-living medusa, often resembles the common jelly- 

 fish. 



JACKSON TURBIDITY UNITS— Measurement of tur- 

 bidity that relates levels of sample liquid in a graduated 

 cylinder to visible loss or merging of the image of a 

 standardized candle, viewed from the top of the col- 

 umn of water, with the lighted candle at a defined 

 distance from the bottom of the graduated column. 



HYPERSALINE — Water with a salt concentration over 

 40 parts per thousand (%o). 



JUVENILE— A young organism essentially similar to 

 an adult, but not sexually mature. 



IMMIGRATION — A movement of individuals into a 

 new population or region. See EMIGRATION, MIGRA- 

 TION, and RECRUITMENT. 



INCIDENTAL CATCH— Catch of a species that is not 

 intended to be caught by a fishery, but is taken along 

 with the species being sought; also known as 

 BYCATCH. 



INDICATOR OF STRESS— Species whose presence 

 or absence in an environment has been documented 

 as correlated with polluted or unpolluted conditions, or 

 ecological stress of other forms. 



INDIRECT DEVELOPMENT— See EMBRYONIC DE- 

 VELOPMENT. 



KINESIS — A randomly directed movement by an ani- 

 mal in response to a sensory stimulus such as light, 

 heat, or touch. When the response is directed, it is 

 called a taxis. See CHEMOTAXIS. 



LACUSTRINE — Pertaining to, or living in, lakes or 

 ponds. 



LAGOON— A shallow pond or channel linked to the 

 ocean, but often separated by a reef or sandbar. 



LARVA — An early developmental stage of an organ- 

 ism that is morphologically different from the juvenile or 

 adult form, intervening between the times of hatching 

 and of juvenile transformation. See EMBRYONIC 

 DEVELOPMENT. 



INFAUNA — Animals living within a substrate. 



INNER SHELF — The continental shelf extending from 

 the mean low tide line to a depth of 20 m. 



INSTAR — The intermolt stage of a young arthropod. 



INSULAR — Of or pertaining to an island or its charac- 

 teristics (i.e., isolated). 



LATERAL LINE — A pressure sensory system located 

 in a line of pores under the skin on both sides of most 

 fishes. The system is connected indirectly with the 

 inner ear and senses water pressure changes due to 

 water movement (including sound waves). 



LC50 — The measured concentration of a toxic sub- 

 stance that kills 50% of a group of test organisms within 

 a specified time period. 



INTERTIDAL — The ocean or estuarine shore zone 

 exposed between high and low tides. 



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