Guarding males of the hermit crab climb up algae to avoid male–male competition

Takuma Kawaminami,Seiji Goshima

doi:10.1007/s10164-014-0411-7

Abstract

Abstract Males of the hermit crab Pagurus filholi show precopulatory guarding behavior in which a male grasps the shell of a mature female with his left cheliped before copulation. Hermit crabs were most common in rocky intertidal areas with cobbles and boulders, while many guarding pairs were observed on fronds of brown algae such as Sargassum confusum in Hakodate Bay, Japan. We examined three hypotheses explaining why the guarding pairs were most common on algae; (1) aggregation place for mature males and females to find mates, (2) avoidance of male–male combat, and (3) avoidance of predators. If solitary males and females climbed up algae, then many guarding pairs were observed after pairing, but only guarding pairs climbed up the algae after removing all crabs. Experiments in aquariums showed that the disturbance rate for guarding pairs due to male–male competition was lower on the algae than in boulder and rocky flat areas, and few disturbances were observed by predatory crabs in all habitat types. These results suggest that the guarding males climb up the fronds of algae to sequester guarded females from rival males and avoid male–male combat. This behavior could be considered as a male counter tactic against indirect female choice mediated by sex pheromones in which females release sex pheromones while guarded, attracting many rival males and inducing male–male competition.

Highlights

Sexual selection usually comprises two important processes; male–male competition and female choice, and there is a controversy as to whether male–male competition facilitates or hampers female choice (Wong and Candolin 2005)
Males of the hermit crab Pagurus filholi show precopulatory guarding behavior in which a male grasps the shell of a mature female with his left cheliped before copulation
Experiments in aquariums showed that the disturbance rate for guarding pairs due to male–male competition was lower on the algae than in boulder and rocky flat areas, and few disturbances were observed by predatory crabs in all habitat types

Summary

Introduction

Sexual selection usually comprises two important processes; male–male competition and female choice, and there is a controversy as to whether male–male competition facilitates or hampers female choice (Wong and Candolin 2005). These two components of sexual selection have traditionally been viewed as complementary in their effects, and competitive interactions between rival males are thought to be beneficial for females (Wiley and Poston 1996). The relative ability of males to monopolize receptive females leads to assuring their paternity and increases their fitness

Methods

Results

Conclusion