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Abstract

In this field study, newly laid egg clutches of Succinea thaanumi, an endemic Hawaiian land snail, were labeled and observed weekly over a 12-mo period. Snails usually laid their clutches under leaf tips and, moreover, this placement affected snail emergence by mitigating the effects of dehydration through the leaf-drip phenomenon. During droughts, the gel surrounding egg clutches dehydrated, pasting the embryos to the backs of leaves. The hygroscopic gel rehydrated once rains resumed. The majority of newly laid clutches contained shell-less embryos which required more time for emergence than embryos laid with visible shells. More shelled embryos were laid subsequent to a 3-wk drought, indicating that snails retained their eggs during adverse environmental conditions and laid them when conditions improved. The snails’ abilities to retain eggs in adverse conditions, but to lay more unshelled embryos over their lifetimes, contributed to their overall reproductive success.