Venom systems have evolved on multiple occasions
across the animal kingdom, and they can act as key
adaptations to protect animals from predators.
Consequently, venomous animals serve as models
for a rich source of mimicry types, as non-venomous
species benefit from reductions in predation risk by
mimicking the coloration, body shape, and/or movement
of toxic counterparts. The frequent evolution
of such deceitful imitations provides notable
examples of phenotypic convergence and are often
invoked as classic exemplars of evolution by natural
selection. Here, we investigate the evolution of fangs,
venom, and mimetic relationships in reef fishes from
the tribe Nemophini (fangblennies). Comparative
morphological analyses reveal that enlarged canine
teeth (fangs) originated at the base of the Nemophini
radiation and have enabled a micropredatory feeding
strategy in non-venomous Plagiotremus spp. Subsequently,
the evolution of deep anterior grooves and
their coupling to venom secretory tissue provide
Meiacanthus spp. with toxic venom that they effectively
employ for defense. We find that fangblenny
venom contains a number of toxic components that
have been independently recruited into other animal
venoms, some of which cause toxicity via interactions
with opioid receptors, and result in a multifunctional
biochemical phenotype that exerts potent hypotensive
effects. The evolution of fangblenny venom has
seemingly led to phenotypic convergence via the formation
of a diverse array of mimetic relationships that
provide protective (Batesian mimicry) and predatory
(aggressive mimicry) benefits to other fishes.
Our results further our understanding of how novel
morphological and biochemical adaptations stimulate
ecological interactions in the natural world