Labrid cleaner fishes show kinematic convergence as juveniles despite variation in morphology

Abstract

Cleaning, a dietary strategy in which mucus or ectoparasites are removed and consumed off other taxa, is performed facultatively or obligately in a variety of species. We explored whether species in the Labridae (wrasses, parrotfishes) of varying ecological specialization employ similar mechanisms of prey capture. In investigating feeding on attached prey among juveniles of 19 species of wrasses, we found that patterns of biting in wrasses are influenced by the interaction between the maxilla and a feature of the premaxilla which we term the maxillary crest. Premaxillary motion during biting appears to be guided by the relative size of the crest. In many cases, this results in a 'premaxillary bite' wherein the premaxillae rapidly move anteroventrally to meet the lower jaws and deliver a protruded bite. Cleaners in the Labrichthyini tribe, however, exhibited reduced or absent maxillary crests. This coincided with a distinct kinematic pattern of prey capture in these labrichthyine cleaners, coupled with some of the fastest and lowest-excursion jaw movements. Although evidence of kinematic specialization can be found in these labrichthyines (most notably in the obligate cleaners in ), we found that facultative cleaners from other lineages similarly evolved reductions in excursions and timing. Convergence in feeding kinematics is thus apparent despite varying degrees of cleaning specialization and underlying morphological features.

Co‐evolution of cleaning and feeding morphology in western Atlantic and eastern Pacific gobies

“…; Baliga et al. ). Given the subtle behavioral and ecological differences between cleaner fishes, it seems unreasonable to expect cleaners to converge on a single feeding morphotype (Côté ; Vaughan et al.…”

“…Within Gobiidae, we found a strong relationship between functional morphology and cleaning, but these exact patterns are not representative of other cleaner fishes. For instance, cleaner wrasses (dedicated, facultative, and juvenile) are all converging on a "picking" morphology that trades jaw leverage for faster jaws and is different from the scraping morphology of cleaner gobies (Wainwright et al 2004;Baliga et al 2017). Given the subtle behavioral and ecological differences between cleaner fishes, it seems unreasonable to expect cleaners to converge on a single feeding morphotype (Côté 2000;Vaughan et al 2017).…”

Adaptive radiation in labrid fishes: A central role for functional innovations during 65 My of relentless diversification

“…Within this lineage, specialized ectoparasite feeding has also evolved, in association with a split in the lower lip that may facilitate exposure of the teeth of the lower jaw to the epithelium (Baliga et al. ).…”

“…Coral feeding in labrids is intimately associated with highly folded lips that are richly endowed with mucus that may protect the fish from the coral's stinging cells and enhance the suction feeding behavior these fish use to remove coral tissue (Huertas and Bellwood 2017). Within this lineage, specialized ectoparasite feeding has also evolved, in association with a split in the lower lip that may facilitate exposure of the teeth of the lower jaw to the epithelium (Baliga et al 2017).…”

Functional niches of cleanerfish species are mediated by habitat use, cleaning intensity and client selectivity

“…One of those complex behaviours is displayed by fish species that obtain food by removing ectoparasites from other fishes (Côté, 2000; Quimbayo et al., 2018; Vaughan et al., 2017). In the most prominent cleanerfishes, such as the wrasse genus Labroides or the goby genus Elacatinus , specialised morphologies that enable the picking and gleaning of ectoparasites or host tissue (Grutter, 1997, 1999, 2000) are distinct characteristics of obligate cleaner species, but offer little evidence for diversification within group (Baliga et al., 2017; Huie et al., 2020). Yet several species of cleaner wrasses coexist on Indo‐Pacific reefs (Adam & Horii, 2012; Mills & Côté, 2010; Oates et al., 2010a).…”