. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. LIFE-CYCLE SYNCHRONY IN MELAMPUS 643 I lowever, the head-foot organization is markedly different from that of the post- larva or spat: the foot is much narrower and more elongate anteriorly (the eyes lie very far back) and posteriorly (where there is a long tail supporting the retained operculum). This intermediate anatomy and behavior may be typical of veligers at settlement although the majority of them will have a shell form closer to that of Figure 3B. Although our evidence can never be more than circumstantial, we are r
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. LIFE-CYCLE SYNCHRONY IN MELAMPUS 643 I lowever, the head-foot organization is markedly different from that of the post- larva or spat: the foot is much narrower and more elongate anteriorly (the eyes lie very far back) and posteriorly (where there is a long tail supporting the retained operculum). This intermediate anatomy and behavior may be typical of veligers at settlement although the majority of them will have a shell form closer to that of Figure 3B. Although our evidence can never be more than circumstantial, we are reason- ably sure that the veligers spend about fourteen days in the plankton. In 1970 considerable settlements must have occurred with the spring tides of July 4 and August 2 (corresponding to egg-laying of June 7 and July 6). Sets of spat samples taken in mid-August (see next section) established that, although a fraction of the o (/) Z LJ •2. 5 10%. AUG. 6 AUG. 13 AUG. 19 AUG. 35 SEPT. I DATES IN 1970 SEPT. 9 OCT. 18 FIGURE 9. The growth of spat stages of Melampus. Sets of histograms show size distri- butions in successive samples of spat from Little Sippewisset in late summer, 1970. Sampling is probably slightly biased against spat of under mm maximum shell dimension. Sample numbers ranged from 47 (Aug. 6) to 149 (Aug. 19), but the histograms indicate the per- centage of the sample in each class interval to facilitate comparison. total settlement can take place below the Mclainpiis zone, the bulk of the return takes place into the exact zone occupied by the adults and that the differences in distribution which occur can be explained on mechanical grounds of water flow. For example, denser settlement is found among Spartina roots along the edges of drainage channels, where some filtering effect (along with increased contact stimuli to the veligers) must occur as each spring high tide recedes from the marshes. Other typical sites for denser settlement are th
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
