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  • Publication
    Accès libre
    Biting cleaner fish use altruism to deceive image-scoring client reef fish
    (2002-10-22)
    Humans are more likely to help those who they have observed helping others previously. Individuals may thus benefit from being altruistic without direct reciprocity of recipients but due to gains in 'image' and associated indirect reciprocity. I suggest, however, that image-scoring individuals may be exploitable by cheaters if pay-offs vary between interactions. I illustrate this point with data on cleaner–client reef fish interactions. I show the following: (i) there is strong variation between cleaners with respect to cheating of clients (i.e. feeding on client tissue instead of parasites); (ii) clients approach cleaners, that they observe cooperating with their current client and avoid cleaners that they observe cheating; (iii) cleaners that cheat frequently are avoided more frequently than more cooperative cleaners; (iv) cleaners that cheat frequently behave altruistically towards their smallest client species; (v) altruistic acts are followed by exploitative interactions. Thus, it appears that cleaners indeed have an image score, which selects for cooperative cleaners. However, cheating cleaners use altruism in potentially low-pay-off interactions to deceive and attract image-scoring clients that will be exploited.
  • Publication
    Accès libre
    Cleaner fish Labroides dimidiatus manipulate client reef fish by providing tactile stimulation
    (2001-07-22) ;
    Würth, Manuela Würth
    The cleaner wrasse Labroides dimidiatus often touches 'client' reef fish dorsal fin areas with its pelvic and pectoral fins. The relative spatial positions of cleaner and client remain constant and the cleaner's head points away from the client's body. Therefore, this behaviour is not compatible with foraging and the removal of client ectoparasites. As clients seek such 'tactile stimulation', it can be classified as an interspecific socio-positive behaviour. Our field observations on 12 cleaners (observation time of 112h) suggest that cleaners use tactile stimulation in order to successfully (i) alter client decisions over how long to stay for an inspection, and (ii) stop clients from fleeing or aggressive chasing of the cleaner in response to a cleaner fish bite that made them jolt. Finally, predatory clients receive tactile stimulation more often than non-predatory clients, which might be interpreted as an extra service that cleaners give to specific partners as pre-conflict management, as these partners would be particularly dangerous if they started a conflict. We therefore propose that cleaner fish use interspecific social strategies, which have so far been reported only from mammals, particularly primates.