Efficiency of Growth in Mytilus edulis and Two Gastropod Veligers

Abstract

GROWTH efficiencies have been studied extensively in domestic animals and in some common laboratory animals¹. Little is known, however, of the utilization of energy in the growth of lower animals. I have been able to show that marine invertebrates may have high growth efficiencies. Efficiency calculations were based on growth-rate and oxygen uptake in Mytilus edulis of different ages, and in veligers of two marine gastropods, Littorina littorea and Nassa reticulata. Rates of growth were calculated from average increases in length in Nature during known intervals of time. Data published by Thorson² were used in calculating growth-rates of veligers of Littorina and Nassa (from the Isefjord, Denmark) and of young metamorphosed Mytilus (from the Sound). I myself measured the growth of Mytilus veligers (from Isefjord). Data on growth of Mytilus during later stages were obtained from the Pacific off La Jolla, California, where Coe³ measured the average increment in length of different age- and size-groups during August–November while maximum growth is taking place. Lengths were first converted into total nitrogen content using the relationship found by Zeuthen⁴ (and unpublished results of Dr. Zeuthen). Then total organic matter was computed, assuming a nitrogen content of 8 per cent of the dry organic matter. Rates of oxygen uptake were obtained from Zeuthen⁴. The oxygen values were converted into organic matter by assuming that 1.2 litres of oxygen is equivalent to 1 gm. of organic matter.