NANOPLANKTON 



N-/ 



Very minute p lankton not retained in a plankton 

 net equipped with no. 25 silk bolting cloth 

 (mesh, 0.03 to 0.04 mm.). 



NATIVE SPECIES 



A species that is part of an area's original 

 biota. 



NATURAL SELECTION 



Processes occurring in nature which result in 

 survival of the fittest and elimination of 

 individuals less well adapted to their 

 environment. 



NAUPLIUS 



Free-swimming microscopic larval stage 

 characteristic of many crustaceans, barnacles, 

 etc. 



NEAP TIDES 



Exceptionally low tides which occur twice each 

 month when the earth, sun and moon are at 

 right angles to each other; these usually 

 occur during the moon's first and third 

 quarters. (See Spring Tides ) 



NEKTON 



Macroscopic organisms swimming actively in 

 water; e.g., fish. (See Plankton ) 



NERITIC ZONE 



Relatively shallow water zone which extends 

 from the high-tide mark to the edge of the 

 continental shelf. 



NET PLANKTON 



Plankton retained in a plankton net equipped 

 with no. 25 silk bolting cloth (mesh, 0.03 

 to 0.04 mm. ) . 



