Abstract
Suction-feeding in fishes is a ubiquitous form of prey capture whose outcome depends both on the movements of the predator and the prey, and on the dynamics of the surrounding fluid, which exerts forces on the two organisms. The inherent complexity of suction-feeding has challenged previous efforts to understand how the feeding strikes are modified when species evolve to feed on different prey types. Here, we use the concept of dynamic similarity, commonly applied to understanding the mechanisms of swimming, flying, walking and aquatic feeding. We characterize the hydrodynamic regimes pertaining to (i) the forward movement of the fish (ram), and (ii) the suction flows for feeding strikes of 71 species of acanthomorph fishes. A discriminant function analysis revealed that feeding strikes of zooplanktivores, generalists and piscivores could be distinguished based on their hydrodynamic regimes. Furthermore, a phylogenetic comparative analysis revealed that there are distinctive hydrodynamic adaptive peaks associated with zooplanktivores, generalists and piscivores. The scaling of dynamic similarity across species, body sizes and feeding guilds in fishes indicates that elementary hydrodynamic principles govern the trophic evolution of suction-feeding in fishes.
Highlights
Feeding is a complex behaviour in which multiple traits interact to determine its outcome
We have shown here that the hydrodynamic regime which pertains to the contribution of swimming, and the hydrodynamic regime that pertains to suction clarify much of the ecological variation in suction-feeding fishes
The scaling of the Reynolds and Womersley numbers across species, body sizes and feeding guilds in fishes indicates that elementary hydrodynamic principles govern the trophic evolution of suction-feeding in fishes
Summary
Feeding is a complex behaviour in which multiple traits interact to determine its outcome. The scaling of the forces is expressed as a ratio, i.e. a dimensionless number, and the nature of the flow determines the appropriate dimensionless number(s) used to assess dynamic similarity This concept enables a comparison of the hydrodynamics that govern the behaviours of animals of different sizes, speeds and shapes. The transition of a species that diverged from a piscivorous ancestor (i.e. residing near the adaptive peak for piscivores) to planktivory may take more time to reach the adaptive peak for planktivores than a species that diverged from a generalist ancestor To account for such phylogenetic effects, we compared several models of trait evolution, pertaining to effect of the feeding guilds on the tempo (rate) and mode (direction) of evolution. All analyses were performed in R v. 4.0.3 [44]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
