. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ARTEMIA SEGMENTATION PATTERN 121 Morphologically, different salinities have no differential effect on relative body proportions, a result to be expected in view of the conclusions of Bond (1932). An inverse relation between total size and salinity, observed by Bond, Heath (1924), and Warren (1938) for larvae from non-excysted eggs in the natural habitat, however, could not be observed for the excysted larvae here used; in the latter, total sizes are identical at equivalent stages of development, irrespective of salinity. The
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ARTEMIA SEGMENTATION PATTERN 121 Morphologically, different salinities have no differential effect on relative body proportions, a result to be expected in view of the conclusions of Bond (1932). An inverse relation between total size and salinity, observed by Bond, Heath (1924), and Warren (1938) for larvae from non-excysted eggs in the natural habitat, however, could not be observed for the excysted larvae here used; in the latter, total sizes are identical at equivalent stages of development, irrespective of salinity. The number of molts between hatching and sexual maturity is not constant. Even when reared in the same medium, slight differences in molting frequency between several larvae may occur. Moreover, there exists a rough statistical relation between salinity and the total number of molts, approximating closely the 0 I/ S4 5 fi 7 8 9 10 II 12 13 14 15 IS 17. 05 FIGURE 1. The effect of salinity on developmental time, from hatching to sexual maturity; absolute growth curves. Abscissa: total larval length; Ordinate: time in days. A-E, media of salt water, specific gravities from respectively; numbers 1-19 above abscissa refer to number of body segments present. above relation between salinity and the time required for complete development; in general, however, the number of molts for a given salinity is somewhat lower than the number of days required for development. In larvae from excysted eggs and under artificial food conditions, a range of 12 to 16 molts was observed between hatching and maturity, at a specific gravity of ; this compares with 25 to 29 molts at a specific gravity of , and gradually decreasing molting frequencies for the intermediate salinity ranges. A staging of larval development according to molts, as Heath has done for non-excysted individuals, would therefore not be possible in the present case. Heath's 13 stages would hold for excysted larvae
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
