PROTOZOA 



Protozoa — 1. A phylum of mostly microscopic, 

 one-celled animals. This group constitutes one 

 of the largest populations in the sea, including 

 some bioluminescent genera. 



2. An often used common name for the mem- 

 bers of the phylum. 



protozoan — One of a phylum (Protozoa) of 

 single-celled animals. See Protozoa. 



proud of the bottom — Resting on the surface of 

 the bottom, that is, not imbedded in the bottom. 



province — A region composed of a group of simi- 

 lar bathymetric features whose characteristics 

 are markedly in contrast with surrounding areas. 

 (62) . ■ 



psammite — (or spelled psammyte). See sand- 

 stone. 



psephite — A coarse fragmental rock (conglom- 

 erate) or deposit composed of rounded pebbles. 

 (2) 



pteropod — (or sea hutter-fly). One of an order 

 (Pteropoda) of pelagic, free-swimming gastro- 

 pods in which the foot is modified into fins ; both 

 shelled and nonshelled forms exist. The accum- 

 ulated shells of these organisms form a type of 

 bottom sediment called pteropod ooze in some 

 ocean areas. See ooze. 



pteropod ooze — A pelagic sediment containing 

 at least 30 percent calcium carbonate in the form 

 of tests of marine animals, the dominant form 

 being pteropods. See ooze. 



puddingstone — See conglomerate. 



puddle — (also called pool, snoio puddle on the 

 ice). 1. /S'ee snow water on the ice. 



2. A small body of water, usually fresh melt 

 water, in a depression or hollow on ice. (68) 



pulse height analyzer — An electronic circuit 

 which sorts and records pulses according to 

 height (energy). 



Such electronic devices are used for sorting of 

 pulses from gamma ray interactions in the de- 

 tector of a gamma ray spectrometer. Ob- 

 served pulses are sorted into adjacent energy 



channels enabling determination of the energy 

 spectra or energy frequency distribution of ob- 

 served gamma rays in a selected energy range 

 (usually to 3 million-electron-volts for gamma 

 ray emitting radioisotopes). Pulse height 

 analyzers may be single or multichannel devices. 

 All multichannel analyzers consist of (1) an 

 analog-to-digital converter which assigns a 

 channel to each input pulse according to its 

 amplitude (energy), (2) a memory which re- 

 cords the number of counts falling into each 

 channel and, (3) a display or readout device 

 indicating the number of counts in each channel. 

 (70) 



pumice — An excessively cellular, glassy lava. It 

 is very light and can float on water until it be- 

 comes waterlogged and sinks. 



pure water — (or distilled toater). Water that 

 contains no impurities. Compare with fresh 

 water. 



purse seine — A large net, used in commercial fish- 

 eries, placed in a circle around a school of fish 

 and drawn together. (35) 



pycnocline — The vertical gradient of density. 



pycnogonid — See sea spider. 



pyramidal iceberg — A pinnacled iceberg of 

 pyramidal shape. (59) 



pyramidal sea — See intersecting waves. 



pyrheliometer — A general term for the class of ac- 

 tinometers which measure the intensity of direct 

 solar radiation. In oceanography, this instru- 

 ment measures the total sun and sky radiation 

 received on a horizontal surface. 



pyrosome — (or fire hody, fire cylinder) . One of a 

 genus {Pyrosoma) of luminescent, pelagic, co- 

 lonial tunicates. Individuals form thimble- 

 shaped colonies commonly 3 or 4 inches long but 

 reaching a length of at least 2 feet. They occur 

 only in warm waters and produce brilliant 

 luminescence resembling long incandescent gas 

 mantles. 



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