Short Communication

Journal of Ethology

, Volume 31, Issue 2, pp 219-221

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

Allocleaning behavior by the sentinel crab Macrophthalmus banzai: a case of mutual cooperation

  • Yurika FujishimaAffiliated withDepartment of Biological Science, Faculty of Science, Nara Women’s UniversityLaboratory of Marine Environmental Microbiology, Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University
  • , Keiji WadaAffiliated withDepartment of Biological Science, Faculty of Science, Nara Women’s University Email author 


The macrophthalmid crab Macrophthalmus banzai performs allocleaning behavior, in which an individual feeds off the carapace or walking legs of a conspecific male or female. Cleaning continues until the recipient (‘cleanee’) rejects the cleaning or the cleaner ceases cleaning. In cases where the recipient did not reject the cleaning, the cleanee often retreated to its own burrow site after the cleaner ceased cleaning, allowing the cleaner to feed on its territory. We suggest that this is mutual cooperation, in which the cleaner assists the recipient to clean the body surface, and the recipient in return provides a feeding ground for the cleaner. Using field observation, we explored the factors responsible for the retreat of the cleanee in response to the cleaning behavior. Factors influencing the retreat of the cleanee were the time of the cleaning incident relative to low tide, the cleanee’s position relative to its own burrow, and the duration of the cleaning bout. The third factor showed that retreat was more common when the cleaning was thorough, which suggests that allocleaning is a form of mutual cooperation in M. banzai.


Allocleaning Mutual cooperation Intertidal crab Macrophthalmus