and ecology of marine and brackish water plants 

 and animals. (15) 



BIOLUMINESCENCE . The emission of light by living 

 organisms. (15) 



BIONEPHELOMETER . This is an instrument for record- 

 ing the intensity of scatter at 90° from a Tyndall 

 beam in a light-tight chamber through which sea- 

 water is pumped from an overside collector. It ap- 

 pears that intensity of scatter may be related to 

 settling volume of the water being examined by the 

 instrument. Settling volumes are used by marine 

 biologists as an indication of standing crop of the 

 water. The instrument itself consists of a Tyndall 

 chamber into which seawater is conducted from a 

 plastic hose through an 8° diffuser. Water is con- 

 ducted from the chamber through an extraction cone 

 to the outlet hose. Extraction ratio in the dif- 

 fuser is approximately 6:1. A light source and a 

 barrier-layer photocell are situated in the cham- 

 ber wall at 90° to the flow axis, disposed at 90 

 to each other. Opposite each is a conical light 

 trap. A plastic window separates the light source 

 and photocell from the seawater. A condensing lens 

 is situated in front of the light source assuring 

 that a parallel beam of light shines through the 

 plastic window into the chamber. Output of the 

 photocell is fed to an amplifier and recorder. (30) 



BIONICS . The study of systems which function after 

 the manner of, or in a manner characteristic of, or 

 resembling, living systems. (31) 



BIOSPHERE . That transition zone between earth and 

 atmosphere within which most forms of terrestrial 

 life are commonly found; the outer portion of the 

 GEOSPHERE and inner or lower portion of the ATMOS- 

 PHERE. (12) 



BIOTA . The animal and plant life of a region; 

 flora and fauna collectively. (38) 



BIOTOPE . A biotope, or niche, is an area of which 

 the principal habitat conditions and the living 

 forms which are adapted to them are uniform. Smal- 

 ler habitat anomalies found within the biotope are 

 called facies. The community of forms in a biotope 

 is called a biocoenosis. Biotopes having certain 

 characteristics in common are united into larger 

 divisions known as biochores . (13) 



BIPOLAR DISTRIBUTION . See BIPOLARITY. 



BIFOLARITY (BIPOLAR DISTRIBUTION) . A break in the 

 continuity of distribution of a species or higher 

 division is called discontinuous distribution, and 

 when this occurs in a meridional direction so that 

 the animals involved are absent from the tropical 

 belt, the phenomena is known as bipolarity or bi- 

 polar distribution. According to older usage, 

 the term referred only to animals living in arctic 

 and antarctic waters, but now it is used also to 

 indicate those living in the temperate zones. The 

 term bipolarity of relationship is used to indicate 

 a bipolar distribution in which animals of higher 

 latitudes are more closely related taxonomically to 

 each other than to those of lower latitudes. There 

 is also bipolarity of phenomena such as are as- 

 sociated with mass vernal production of diatoms, 

 for example, or with production of great numbers 

 of individuals but of relatively few species . 

 Northern littoral or surface pelagic stenohaline 

 animals that are sufficiently euryhaline and eury- 

 bathic, may form a continuous distribution from 

 high northern to high southern latitudes by living 

 in deep water in that part of their meridional range 

 crossing the equitorial region. This is referred 

 to as tropical submergence. The term bipolar- 

 epiplanktonic is used to describe the distribution 

 of related high northern and high southern plank- 

 tonic animals connected through tropical submer- 

 gence. (13) 



BIPOLARITY OF PHENOMENA . See BIPOLARITY. 



BIPOLARITY OF RELATIONSHIP . See BIPOLARITY. 



BIRAMOUS . Consisting of or possessing two branches, 

 as a crustacean appendage. (19) 



BITTERN . The liquid remaining after sea water has 

 been concentrated by evaporation until salt has 

 crystallized. (24) 



BLACK AND WHITE ICEBERG . An ICEBERG having a dark, 

 opaque portion containing sand and stones, and sep- 

 arated from the white portion by a definite line of 

 demarcation. (25) 



BLACK ICE . Ice crust which is transparent enough 

 to reveal the color of the sea water beneath. (17) 



BLACK STREAM . See KUROSHIO CURRENT. 



BLIND ROLLERS . Long, high swells which have in- 

 creased in height, almost to the breaking point, 

 as they pass over shoals or run in shoaling water. 

 (11) 



BLINK . A glare on the underside of extensive cloud 

 areas created by light reflected from snow or ice 

 covered surfaces; also observable in a clear sky. 

 Blink caused by ice surfaces is usually yellowish- 

 white in contrast to the whitish, brighter glare 

 caused by snow surfaces. This distinction is some- 

 times difficult to perceive. In contrast to SNOW- 

 BLINK and ICEBLINK, the sky is dark above bare land 

 or open water surfaces. (25) 



BLOCK . A fragment of SEA ICE ranging in size from 

 6 to 30 feet across. (25) 



BLOCKED ADMITTANCE . The blocked admittance of a 

 transducer is the input admittance when the output 

 terminals are short-circuited. (4) 



BLOCKED IMPEDANCE . The blocked impedance of a 

 transducer is its input impedance when its load 

 terminals are open-circuited. (4) 



BLOCKY ICEBERG . An ICEBERG with steep, precipitous 

 sides, and with either a horizontal or nearly hori- 

 zontal upper surface. (25) 



BLUE-GREEN ALGAE (MYXOPHYCEAE) . A class of algae 

 which contains only small, poorly organized plants, 

 some consisting of only a single cell, while others 

 are multicellular. The blue color is due to a 

 water-soluble accessory pigment, phycocyanin. How- 

 ever, some forms, such as Trichodesmium erythraeum, 

 exhibit a red pigment and is responsible for the red 

 color sometimes observed in surface waters. The Red 

 Sea, for instance, owes its name to this form. Some 

 brackish-water forms are responsible for the slim- 

 ing occasionally observed in the calm waters of 

 fjords and in the Gulf of Bothnia. Although wide- 

 spread in both fresh and brackish-water, Myxophyceae 

 is of less general importance in the oceans than 

 GREEN, BROWN, RED and YELLOW-GREEN ALGEA. (13) 



BLUE ICE . The oldest and hardest form of GLACIER 

 ICE. It is distinguished by a slightly bluish or 

 greenish color. 



BLUE MUD . A common variety of deep-sea mud, having 

 a bluish-gray color due to the presence of organic 

 matter and finely divided iron sulfides; calcium 

 carbonate present in variable amounts to 35 per cent. 

 (27) 



BLUFF . A cliff with a broad face, or a relatively 

 long strip of land rising abruptly above surround- 

 ing land or a body of water. (17) 



15 



