. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 254 DAVID V. BUCHANAN AND RAYMOND E. MILLEMANN. I mm FIGURE 3. Prezoea of Cancer magister after hatching from the egg. Churchill (1942), on the basis of laboratory studies, stated that a free prezoeal stage, which lasted from 30 to 60 minutes, was normal in the life history of the blue crab, Callinectes sapidus. However, Sandoz and Rogers (1944) believed that their experimental data did not support Churchill's statement. They concluded that unfavorable environmental conditions, such as suboptimal salinities, were re- sponsib
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 254 DAVID V. BUCHANAN AND RAYMOND E. MILLEMANN. I mm FIGURE 3. Prezoea of Cancer magister after hatching from the egg. Churchill (1942), on the basis of laboratory studies, stated that a free prezoeal stage, which lasted from 30 to 60 minutes, was normal in the life history of the blue crab, Callinectes sapidus. However, Sandoz and Rogers (1944) believed that their experimental data did not support Churchill's statement. They concluded that unfavorable environmental conditions, such as suboptimal salinities, were re- sponsible for the occurrence of free prezoeae, because in their experiments the numbers of free prezoeae increased as salinities decreased. They found no prezoeae when eggs were hatched at salinities ranging from to 32^c, but at a salinity of W%0, 90 to 100% of the hatched larvae remained as prezoeae. We found the same for C. magister prezoeae at low salinities, but at high salinities all of our prezoeae molted to zoeae. Sandoz and Rogers (1944) observed their eggs only twice daily, and therefore they could have failed to see the short-lived prezoeae at the higher salinities. The data of Sandoz and Rogers (1944), therefore, do not refute the belief of Churchill (1942), and for the same reason neither do the data of Costlow and Bookhout (1959), who also reported that eggs of C. sapidus at salinities ranging from to 32%0 always hatched as first-stage zoeae. Costlow and Bookhout (1960) observed the eggs of six species of Brachyura, including C. sapidus, once daily and reported that most of the eggs of all species hatched as zoeae. Knudsen (1959) and Williams (1968) found that eggs of the crabs Paraxanthias taylori and Carcinus niacnas, respectively, normally hatched as prezoeae, and the latter author reported that the average duration of the prezoeal stage of C. maenas was 4 to 5 minutes. It is clear, therefore, that the early life history of the blue crab and of other crabs in
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