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Weird Science: Cleaners & Mimics

Divers and snorkelers visiting the coral reefs of the Indo-Pacific region have often noticed an unusual behavior among the large predatory fish of the reef. Groupers, snappers, and eels will visit special spots on the reef and assume a passive posture, open their mouths and gill covers. In swims a very small fish, but it is not eaten! The cleaner wrasse carefully grooms the skin and gills of its large client, removing dead and itchy skin and parasites. This mutualistic relationship keeps the large fish comfortable, while providing the small cleaner fish with a meal.

Close observers will note an occasional flinch by some of the fish being cleaned; this is because sometimes, a third fish enters the scene. The sabretooth blenny is a mimic of the cleaner wrasse. Its color, body shape, even its swimming style, all closely resemble the wrasse. But this blenny is no helpful cleaner. The sabretooth is a clever and vicious parasite, sneaking close enough to its victims to grab a mouthful of tender flesh. (See SF Fig. 4.11.)

SF Fig. 4.11.  (A) Big eye squirrelfish (Priacanthus hamrur) being serviced by cleaner wrasse (Labroides dimidiatus)

Image Courtesy of Nhobgood

(B) The blue-lined sabertooth blenny (Plagiotremus rhinorhynchos) mimics the blue-striped cleaner wrasse by copying its dance but then biting the biting client instead of cleaning it

Image Courtsey of Jenny Huang

Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.