Life history evolution in hermit crabs: A review
2000
Wada, S. (Kochi Univ., Tosa (Japan). Usa Marine Biological Inst.)
Several hypotheses dealing with the relationships between the life history traits of hermit crab and shell resource were reviewed. Hermit crabs utilize gastropod shells as microhabitats. Since shells affect various fitness components of hermit crabs, such as settlement success, survival rate, growth rate and reproduction, shells largely resemble the microhabitat resource for many sessile animals and plants. Phenotypic plasticity, geographic variation, and interspecific variation in life history traits may be caused by spatio-temporal variation in shell availability. Particularly, the hypothesis for inter-specific differences of temperate zone hermit crabs in annual spawning schedule was minutely addressed in this review. Annual spawning schedules can be divided into two types: the one-clutch type and the multiple-clutch type. Differences in maximizing the fitness component might explain specific differences in annual spawning times and some related traits. Species that spawn several clutches a year and have a short incubation period might maximize the number of larval releases per annum when the shell supply is small and unpredictable for settling and newly settled crabs. For species with a single annual clutch, a long incubation period and an early spring hatch out might be selected to maximize larval survival until settlement if sufficient food and shells are available in early spring, which is considered the optimal season for larval settlement success.
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