Agonistic and mating behavior in relation to chela features in Hemigrapsus takanoi and H. sinensis (Brachyura, Varunidae)

Is the Setal Patch on the Chelae of Hemigrapsus takanoi and Hemigrapsus sinensis (Crustacea, Brachyura, Varunidae) Advantageous in Fighting and Mating?

“…However, neither the dimorphic species nor the non‐dimorphic species in the present study exhibit any visual courtship behavior prior to copulation (Miyajima et al. ). In addition, our trials examining the occurrence of pairing behavior and female choice demonstrated that females changed their behavior depending on the presence or absence of the male setal patch during copulation.…”

“…Setal patches do not appear to be used during either intrasexual agonistic interactions or the mating behavior of either species (Miyajima et al. ). The frequency of intrasexual agonistic interactions is more prominent in the dimorphic species compared to the non‐dimorphic species, although no differences have been observed between the sexes of either species (Miyajima et al.…”

“…However, when the setal patch is present, individuals engaging in intrasexual agonistic interactions use their chelae more frequently than their walking legs by grasping each other, whereas when the setal patch is absent, this scenario is reversed: Individuals more frequently use their walking legs than their chelae by touching and pushing each other (Miyajima et al. ).…”

“…However, in the non‐dimorphic species H. sinensis , males sometimes guard females after copulation, and unlike the dimorphic species, the initiation of mating involves the approach of either the male or female, and males rarely capture females with their chelae (Miyajima et al. ).…”

Characteristics of aggressive behaviors of five species of the genus <i>Ilyoplax</i> (Brachyura, Dotillidae) in East Asia

“…During the reproductive season the females more often hide in the burrows than the males, which can cause more male-biased sex ratio of the active crabs than the population sex ratio. Male-biased aggressiveness has been reported in many brachyuran species in terms of both aggression frequency (Beer, 1959;Griffin, 1968;Seiple & Salmon, 1982;Salmon, 1984) and the relative frequency of the behavioral elements of mutual aggressive acts (Warner, 1970;Vannini & Sardini, 1971;Crane, 1975;Jachowski, 1974;Swartz, 1976;Salmon, 1984;Worfrath, 1993;Miyajima et al, 2012). By contrast, in some brachyuran species, both sexes are similarly aggressive in terms of frequency and types of behaviors (Huber, 1987;Karplus et al, 1998).…”