Predatory foraging tactics correspond with aggressive mimetic fidelity in carnivorous blenniid fishes on coral reefs

Abstract

Mimic species vary widely in how faithfully they resemble their models. On coral reefs, several species of the family Blenniidae mimic the bluestreak cleaner wrasse, Labroides dimidiatus (Labridae), which removes ectoparasites from other fishes, enabling the mimics to approach and bite parts of fish bodies undetected. The false cleanerfish, Aspidontus taeniatus, and bluestriped fangblenny, Plagiotremus rhinorhynchos, are well-known blennies that feed on fins, scales, and mucus of other fishes while exhibiting aggressive mimicry of the cleaner wrasse. The former (a perfect mimic) exhibits elaborate mimetic features throughout its life history, whereas the latter (an imperfect mimic) shows mimetic traits only facultatively. We conducted three-dimensional (3D) video recordings of their predatory foraging behaviors in the wild using an underwater stereo video system. Our study focused on three blenniid species, including the piano fangblenny, P. tapeinosoma, a non-mimic blenny with similar feeding habits. Our results showed that the false cleanerfish (perfect mimic) employed a “sneaky” tactic, slowly approaching small target fish and biting their caudal fins from a short distance. By contrast, the piano fangblenny (non-mimic) employed a “hit-and-run” tactic, approaching swiftly from a long distance and ripping off scales or mucus directed at the lateral body of large target fish. The bluestriped fangblenny, which exhibits lower mimetic fidelity (imperfect mimic), employed an intermediate tactic, approaching from a moderate distance between that of a perfect mimic and a non-mimic and ripping off scales or mucus of medium-sized fish. These findings suggest that differences in predatory tactics may have corresponded to the evolution of mimetic fidelity in aggressive mimic blennies.