The life history characteristics of the mole crab (Hippa truncatifrons) were studied using monthly or bimonthly sampling at a cobble shore on the Miho Peninsula, located in the inner part of Suruga Bay, central Japan, between April 2013 and March 2014. A total of 523 individuals was collected, comprising 276 males (carapace length, CL, 3.4–9.7 mm) and 247 females (CL 4.9–15.0 mm). The number of individuals collected showed two peaks (>10 individuals per station), in early summer and autumn, and decreased to only a few per station in winter. The population exhibited a unimodal CL distribution, with the modes of CL gradually increasing between April and July. Smaller individuals (<4.0 and <7.0 mm CL for males and females, respectively) appeared in August. After August, bimodal distributions of CL were recorded, with fewer individuals in the larger size group. This indicates the mean lifespan was estimated to be almost one year, with some individuals surviving for up to two years after hatching. Ovigerous females were observed between May to September, but were most abundant during June and July. Ovarian development corresponded with the occurrence of ovigerous females. The size at sexual maturity for females was estimated to be 10.2 mm CL. Batch fecundity ranged from seven to 1801 and was correlated with CL for some embryonic stages in all breeding season and early embryonic stages in the early breeding season. Some ovigerous females with late embryonic developmental stages had mature ovaries, indicating multiple spawning by some females during one reproductive season. The Suruga Bay population showed a typical life history similar to that of the Sagami Bay and Hokuriku populations, but different from that of extreme areas, such as Aomori (the northern limit of their range) and an island in Mikawa Bay with large-sized individuals.
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