. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MIGRATORY HABITS OF LIMNORIA 65 far from the parent burrow, the young produced on the block can readily be dis- tinguished from young which might have migrated to the block. Even specimens which have become sexually mature, and no longer associated with the parent burrow can usually be distinguished from sexually mature young migrants to the blocks because they occur in significantly larger numbers than do the young (small) migrants. Rate of Growth. The growth rate of Limnoria tripunctata was determined by culturing individ-
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MIGRATORY HABITS OF LIMNORIA 65 far from the parent burrow, the young produced on the block can readily be dis- tinguished from young which might have migrated to the block. Even specimens which have become sexually mature, and no longer associated with the parent burrow can usually be distinguished from sexually mature young migrants to the blocks because they occur in significantly larger numbers than do the young (small) migrants. Rate of Growth. The growth rate of Limnoria tripunctata was determined by culturing individ- uals in the laboratory and from measurements of the growth of young on test blocks for two-, three-, and four-month intervals. The maximum growth rate seasonally as found in test block exposures is shown in Figure 4. An evident feature is the 0 .830 — LABORATORY irt £• FIELD DATA 5 0664 ^SUMMER TO FALL 5 z ^^ .LATE SPRING. WINTER 120 150 180 310 240 DAYS FIGURE 4. Limnoria tripunctata. Individual growth rate at different seasons : late spring, average temperature 19° C.; summer to fall, average temperature 22° C.; winter, average tem- perature 15° C.; laboratory culture average temperature 15° C. Measurements in field are from broods hatched on test blocks, those in laboratory, from individual specimens. seasonal difference in growth rate of the young. Those emerging in winter require roughly twice as long to reach size class 5 (with ; mm. pleotelson width) as do the spring young, and three times as long as the summer young. Thus in- creased crowding from growth of individual animals (distinguished from increased crowding resulting from addition of new individuals) would be greatest during spring and summer. Population Growth. Some idea can be had of the population growth by direct observation of the number and size of broods produced by migrant females during different portions of the year, namely on test blocks that were in place for successive 2-, 3- an
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
