. A biology of Crustacea. Crustacea. I9SI 1952. ACE IN YEARS Fig. 31. Growth curves of Crustacea. A, a single female of Daphnia magna, reared in the labora- tory. B, Balanus crenatus (Cirripedia) grown in conditions of continual submergence. Note the stoppage of growth in winter of the specimens settling in April, and the way in which the specimens settling in September catch up with those settling earlier (after Barnes and Powell, 1953). C, Cancer pagurus (Decapoda, Brach- yura) the edible crab of Europe. (Based on data given by Pearson, 1908). The actual amount of growth which occurs at each
. A biology of Crustacea. Crustacea. I9SI 1952. ACE IN YEARS Fig. 31. Growth curves of Crustacea. A, a single female of Daphnia magna, reared in the labora- tory. B, Balanus crenatus (Cirripedia) grown in conditions of continual submergence. Note the stoppage of growth in winter of the specimens settling in April, and the way in which the specimens settling in September catch up with those settling earlier (after Barnes and Powell, 1953). C, Cancer pagurus (Decapoda, Brach- yura) the edible crab of Europe. (Based on data given by Pearson, 1908). The actual amount of growth which occurs at each moult varies with the age of the crusta- cean. Sometimes no growth occurs at all; rarely, as in some indi- viduals of Daphnia longispina, a decrease in size is found towards the end of life. By measur- ing the increase in size at each moult, or by measuring an individual at intervals throughout its life, a curve may be drawn which shows how growth varies during a lifetime. Three examples are given in figs. 31 a-c. It is important to notice the difference in the time scales, and to realise that curves of this sort can be considerably modified by environ- mental conditions. The growth of barn- acles, once they have settled, presents some interesting differences from the growth of more normal Crustacea. The tough outer shell is not cast off, but is added to at its base, so that the shell increases in height and basal diameter. The more delicate coverings of the limbs and body within the shell are cast. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Green, J. (James), 1928-. Chicago, Quadrangle Books
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Keywords: ., bookcentury1900, bookcollectionbiodiversit, booksubjectcrustacea
