BACTERIA IN THE DEEP SEA 



By Claude E. Zobell and Richard Y. Morita 



Scripps Institution of Oceanography 

 University of California, La JoUa 



Bacteria are simple micro-organisms each consisting of a single cell. 

 Some varieties, called cocci or coccus, are almost spherical or ball-shaped. 

 Rod-shaped bacteria are called bacilli. Those that are curved like a 

 comma are called vibrio. Spirilla is the term applied to spiral-shaped or 

 complexly curved bacteria. Some bacilli and all vibrio and spirilla have 

 flagella, long whip-like appendages that serve as organs of locomotion. 



Numerous genera of each of these four main morphological forms 

 occur in the sea. The genera differ in shape, size, structure, and in many 

 other characteristics, including food requirements, salinity preference, tem- 

 perature tolerance, physiological activity, colour, and colonial behaviour. 

 Their form and structure can be observed with a good microscope, but 

 it is necessary to cultivate bacteria in nutrient mediums in order to under- 

 stand their physiology and growth characteristics. 



Bacterial cells of different species range in length from less than 0.2 

 to more than 100 microns; the average length of most marine species is 

 between 0.5 and 5 microns. The average diameter is near one micron. 

 (A micron is 1/10,000 centimetre.) 



In spite of their small size, bacteria are so numerous that they may 

 constitute an appreciable part of the volume or total weight of living 

 organisms in the sea. When food is plentiful and other environmental 

 conditions are favourable, bacteria grow and reproduce at a remarkable 

 rate. It is not uncommon for bacteria to reach maturity and reproduce 

 (by transverse fission) in less than an hour. 



For food, bacteria consume virtually all types of organic matter regard- 

 less of its composition or state — ■ particulate, colloidal, or dissolved. All 

 classes of carbohydrates, proteins, and lipids are digested by certain 

 varieties of bacteria. They thrive on organic wastes such as animal excre- 

 ment. They attack and quickly decompose the remains of both plants 

 and animals. A few species of bacteria, known as pathogens, start to 

 digest plants and animals even before the infected organisms are dead. 



Because of their voracious appetites for all kinds of organic materials, 

 bacteria are the principal scavengers in the sea. So effective are they in 

 decomposing or mineralizing organic wastes that the ocean has been de- 

 scribed as the world's largest and most efficient septic tank. Actually only 



