Dynamic color change in the grouper during interspecific interactions and swimming.

Animals can change their body color for various ecological functions. In fish, rapid dynamic color change is primarily known in contexts of intraspecific communication and camouflage, while examples in interspecific contexts are rare. We studied dynamic color changes and their associated behaviors in the grouper in its native coral reef environment in the Red Sea.

Post-Larval Processes Reduce the Diversity of Coral Reef Fish Communities.

The difficulties in obtaining species-level abundance estimates of marine larvae have hindered comparisons of diversity across life stages, severely limiting our knowledge of how adult diversity is maintained. To explore factors shaping diversity across life stages, we surveyed adult coral reef fishes, compiled data on their ecological and life history traits and paired these with a unique dataset of species-level larval abundances. Relative larval abundance was more even compared to adults and matched random expectations, whereas the adult community was markedly uneven and less functionally diverse, suggesting species filtering effects.

A multi-peak performance landscape for scale biting in an adaptive radiation of pupfishes.

The physical interactions between organisms and their environment ultimately shape diversification rates, but the contributions of biomechanics to evolutionary divergence are frequently overlooked. Here, we estimated a performance landscape for biting in an adaptive radiation of Cyprinodon pupfishes, including scale-biting and molluscivore specialists, and compared performance peaks with previous estimates of the fitness landscape in this system. We used high-speed video to film feeding strikes on gelatin cubes by scale eater, molluscivore, generalist and hybrid pupfishes and measured bite dimensions.

Multiple performance peaks for scale-biting in an adaptive radiation of pupfishes.

The physical interactions between organisms and their environment ultimately shape their rate of speciation and adaptive radiation, but the contributions of biomechanics to evolutionary divergence are frequently overlooked. Here we investigated an adaptive radiation of pupfishes to measure the relationship between feeding kinematics and performance during adaptation to a novel trophic niche, lepidophagy, in which a predator removes only the scales, mucus, and sometimes tissue from their prey using scraping and biting attacks. We used high-speed video to film scale-biting strikes on gelatin cubes by scale-eater, molluscivore, generalist, and hybrid pupfishes and subsequently measured the dimensions of each bite.

A power amplification dyad in seahorses.

Throughout evolution, organisms repeatedly developed elastic elements to power explosive body motions, overcoming ubiquitous limits on the power capacity of fast-contracting muscles. Seahorses evolved such a latch-mediated spring-actuated (LaMSA) mechanism; however, it is unclear how this mechanism powers the two complementary functions necessary for feeding: rapidly swinging the head towards the prey, and sucking water into the mouth to entrain it. Here, we combine flow visualization and hydrodynamic modelling to estimate the net power required for accelerating the suction feeding flows in 13 fish species.

A new theoretical performance landscape for suction feeding reveals adaptive kinematics in a natural population of reef damselfish.

Understanding how organismal traits determine performance and, ultimately, fitness is a fundamental goal of evolutionary eco-morphology. However, multiple traits can interact in non-linear and context-dependent ways to affect performance, hindering efforts to place natural populations with respect to performance peaks or valleys. Here, we used an established mechanistic model of suction-feeding performance (SIFF) derived from hydrodynamic principles to estimate a theoretical performance landscape for zooplankton prey capture.

Trophic guilds of suction-feeding fishes are distinguished by their characteristic hydrodynamics of swimming and feeding.

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.

Treatment-level impacts of microplastic exposure may be confounded by variation in individual-level responses in juvenile fish.

Microplastic (MP) pollution is a key global environmental issue and laboratory exposure studies on aquatic biota are proliferating at an exponential rate. However, most research is limited to treatment-level effects, ignoring that there may be substantial within-population variation in responses to anthropogenic stressors. MP exposure experiments often reveal considerable, yet largely overlooked, inter-individual variation in particle uptake within concentration treatments.

Elastic energy storage in seahorses leads to a unique suction flow dynamics compared with other actinopterygians.

Suction feeding is a dominant prey-capture strategy across actinopterygians, consisting of a rapid expansion of the mouth cavity that drives a flow of water containing the prey into the mouth. Suction feeding is a power-hungry behavior, involving the actuation of cranial muscles as well as the anterior third of the fish's swimming muscles. Seahorses, which have reduced swimming muscles, evolved a unique mechanism for elastic energy storage that powers their suction flows.

Work that body: fin and body movements determine herbivore feeding performance within the natural reef environment.

Herbivorous fishes form a keystone component of reef ecosystems, yet the functional mechanisms underlying their feeding performance are poorly understood. In water, gravity is counter-balanced by buoyancy, hence fish are recoiled backwards after every bite they take from the substrate. To overcome this recoil and maintain contact with the algae covered substrate, fish need to generate thrust while feeding.

Coral tentacle elasticity promotes an motion that improves mass transfer.

Corals rely almost exclusively on the ambient flow of water to support their respiration, photosynthesis, prey capture, heat exchange and reproduction. Coral tentacles extend to the flow, interact with it and oscillate under the influence of waves. Such oscillating motions of flexible appendages are considered adaptive for reducing the drag force on flexible animals in wave-swept environments, but their significance under slower flows is unclear.

Hydrodynamic Simulations of the Performance Landscape for Suction-Feeding Fishes Reveal Multiple Peaks for Different Prey Types.

The complex interplay between form and function forms the basis for generating and maintaining organismal diversity. Fishes that rely on suction-feeding for prey capture exhibit remarkable phenotypic and trophic diversity. Yet the relationships between fish phenotypes and feeding performance on different prey types are unclear, partly because the morphological, biomechanical, and hydrodynamic mechanisms that underlie suction-feeding are complex.

The hydrodynamic regime drives flow reversals in suction-feeding larval fishes during early ontogeny.

Fish larvae are the smallest self-sustaining vertebrates. As such, they face multiple challenges that stem from their minute size, and from the hydrodynamic regime in which they dwell. This regime, of intermediate Reynolds numbers, was shown to affect the swimming of larval fish and impede their ability to capture prey.

Pelagic fish predation is stronger at temperate latitudes than near the equator.

Species interactions are widely thought to be strongest in the tropics, potentially contributing to the greater number of species at lower latitudes. Yet, empirical tests of this "biotic interactions" hypothesis remain limited and often provide mixed results. Here, we analyze 55 years of catch per unit effort data from pelagic longline fisheries to estimate the strength of predation exerted by large predatory fish in the world's oceans.

Rapid adaptive evolution of scale-eating kinematics to a novel ecological niche.

The origins of novel trophic specialization, in which organisms begin to exploit resources for the first time, may be explained by shifts in behavior such as foraging preferences or feeding kinematics. One way to investigate behavioral mechanisms underlying ecological novelty is by comparing prey capture kinematics among species. We investigated the contribution of kinematics to the origins of a novel ecological niche for scale-eating within a microendemic adaptive radiation of pupfishes on San Salvador Island, Bahamas.

The Levantine jellyfish Rhopilema nomadica and Rhizostoma pulmo swim faster against the flow than with the flow.

Jellyfish locomotion and orientation have been studied in the past both in the laboratory, testing mostly small jellyfish, and in the field, where it was impossible to control the seawater currents. Utilizing an outdoor water flume, we tested the locomotion of jellyfish when swimming against and with currents of up to 4.5 cm s.

The interaction between suction feeding performance and prey escape response determines feeding success in larval fish.

The survival of larval marine fishes during early development depends on their ability to feed before depleting their yolk reserves. Most larval fish capture prey by expanding their mouth, generating a 'suction flow' that draws the prey into it. These larvae dwell in a hydrodynamic environment that impedes their ability to capture even non-evasive prey; however, the marine environment is characterized by an abundance of evasive prey, predominantly copepods.

Prepared for the future: A strong signal of evolution toward the adult benthic niche during the pelagic stage in Labrid fishes.

The morphology of organisms reflects a balance between their evolutionary history, functional demands, and biomechanical constraints imposed by the immediate environment. In many fish species, a marked shift in the selection regime is evident when pelagic larvae, which swim and feed in the open ocean, settle in their adult benthic habitat. This shift is particularly dramatic in coral-reef fishes, where the adult habitat is immensely complex.

Dissecting a potential spandrel of adaptive radiation: Body depth and pectoral fin ecomorphology coevolve in Lake Malawi cichlid fishes.

The evolution of body shape reflects both the ecological factors structuring organismal diversity as well as an organism's underlying anatomy. For instance, body depth in fishes is thought to determine their susceptibility to predators, attractiveness to mates, as well as swimming performance. However, the internal anatomy influencing diversification of body depth has not been extensively examined, and changes in body depth could arise as a by-product of functional changes in other anatomical structures.

Conserved spatio-temporal patterns of suction-feeding flows across aquatic vertebrates: a comparative flow visualization study.

Suction feeding is a widespread prey capture strategy among aquatic vertebrates. It is almost omnipresent across fishes, and has repeatedly evolved in other aquatic vertebrates. By rapidly expanding the mouth cavity, suction feeders generate a fluid flow outside of their mouth, drawing prey inside.