502 



BIOLOGY OF THE SEAS OF THE U.S.S.R 

 Table 205 



must be explained by the latter. In the Sea of Azov five-year-old C. edule are 

 23 to 26 mm long, while the English ones are 39 to 42 mm; moreover, off the 

 shores of England they live up to nine years, and off the shores of the Murman 

 peninsula to eleven years, and they attain an even bigger size. Cardium, like 

 Nereis, takes part in various biocoenotic groupings in different parts of the 

 Sea. 



Cardium-Syndesmya is the most usual grouping found in the Sea of Azov, 

 mostly at depths of 8 to 16 m and on mud-floors. The quantitative ratio of 

 individual components for the whole C. edule biocoenosis is given in Tables 

 205, 206 and 207. Thus the gain in weight in C. edule biomass consists of the 

 settling of the young, the migration of the one-year-old from the deeper parts, 

 and the growth of all age groups. The loss of biomass is the result of the three 

 first age groups being devoured (fish do not feed on four- and five-year-olds) ; 



