Scaling of Burial Mechanics in Parophrys vetulus, the English Sole

Flatfishes (Pleuronectiformes) rapidly bury themselves under sediments using body undulations and fin movements. During burial, a fish must fluidize a volume of the substrate to displace it into the water column and distribute it over the surface of the body. Thus the burial behavior forces the fish to interact with the fluid environment and a granular medium and is affected by size of the organism and grain size. We used the English Sole, Parophrys vetulus, as a model to explore the effects of scaling on burial. We recorded burial events from 15 fish across a size range (5 to 30 cm in total length), keeping sand grain size consistent, using high speed video at 250 fps and determined undulation frequency, time to burial, and percent body coverage. We found larger fishes took longer to bury and moved with a lower undulation frequency, but were able to cover themselves as effectively as smaller fish (91.6%). Undulation frequency decreased with body length to the -0.53 power; time to burial increased to the 0.67 power. We also used 5 individual fish of similar size (5.7 – 8.1 cm) and changed the size of the particle provided as substrate (125 – 710 microns). We found grain size does not affect the undulation frequency or time to burial of small fish, but as particle size increases, the percentage of the body covered decreases. It is possible that fish cannot fluidize particles of larger grain sizes as effectively as they can smaller grain sizes. Taken together, these results reveal that the timing of flatfish burial is a function of fish size and the success of the behavior is affected by the relative grain size of the sediment

Modelling tooth–prey interactions in sharks: the importance of dynamic testing

The shape of shark teeth varies among species, but traditional testing protocols have revealed no predictive relationship between shark tooth morphology and performance. We developed a dynamic testing device to quantify cutting performance of teeth. We mimicked head-shaking behaviour in feeding large sharks by attaching teeth to the blade of a reciprocating power saw fixed in a custom-built frame. We tested three tooth types at biologically relevant speeds and found differences in tooth cutting ability and wear. Teeth from the bluntnose sixgill (Hexanchus griseus) showed poor cutting ability compared with tiger (Galeocerdo cuvier), sandbar (Carcharhinus plumbeus) and silky (C. falciformis) sharks, but they also showed no wear with repeated use. Some shark teeth are very sharp at the expense of quickly dulling, while others are less sharp but dull more slowly. This demonstrates that dynamic testing is vital to understanding the performance of shark teeth

Data from: Modelling tooth–prey interactions in sharks: the importance of dynamic testing

The shape of shark teeth varies among species, but traditional testing protocols have revealed no predictive relationship between shark tooth morphology and performance. We developed a dynamic testing device to quantify cutting performance of teeth. We mimicked head-shaking behaviour in feeding large sharks by attaching teeth to the blade of a reciprocating power saw fixed in a custom-built frame. We tested three tooth types at biologically relevant speeds and found differences in tooth cutting ability and wear. Teeth from the bluntnose sixgill (Hexanchus griseus) showed poor cutting ability compared with tiger (Galeocerdo cuvier), sandbar (Carcharhinus plumbeus) and silky (C. falciformis) sharks, but they also showed no wear with repeated use. Some shark teeth are very sharp at the expense of quickly dulling, while others are less sharp but dull more slowly. This demonstrates that dynamic testing is vital to understanding the performance of shark teeth

Data from: Effects of organism and substrate size on burial mechanics of English sole, Parophrys vetulus

Flatfishes use cyclic body undulations to force water into the sediment and fluidize substrate particles, displacing them into the water column. When water velocity decreases, suspended particles settle back onto the fish, hiding it from view. Burial may become more challenging as flatfishes grow because the area to be covered increases exponentially with the second power of length. In addition, particle size is not uniform in naturally occurring substrates, and larger particles require higher water velocities for fluidization. We quantified the effects of organism and particle-size scaling on burial behavior of English Sole, Parophrys vetulus. We recorded burial events from a size range of individuals (5-32 cm TL), while maintaining constant substrate grain-size. Larger fish used lower cycle frequencies and took longer to bury, but overall burial performance was maintained (~100% coverage). To test the effect of particle size on burial performance, individuals of similar lengths (5.7-8.1 cm TL) were presented with different substrate sizes (0.125-0.710 mm). Particle size did not affect cycle frequency or time to burial, but fish did not achieve 100% coverage with the largest particles because they could not fluidize this substrate. Taken together, these results suggest that both body size and substrate grain size can potentially limit the ability of flatfishes to bury: a very large fish (>150 cm) may move too slowly to fluidize all but the smallest substrate particles and some particles are simply too large for smaller individuals to fluidize

Data from: Effects of organism and substrate size on burial mechanics of English sole, Parophrys vetulus

Flatfishes use cyclic body undulations to force water into the sediment and fluidize substrate particles, displacing them into the water column. When water velocity decreases, suspended particles settle back onto the fish, hiding it from view. Burial may become more challenging as flatfishes grow because the area to be covered increases exponentially with the second power of length. In addition, particle size is not uniform in naturally occurring substrates, and larger particles require higher water velocities for fluidization. We quantified the effects of organism and particle-size scaling on burial behavior of English Sole, Parophrys vetulus. We recorded burial events from a size range of individuals (5-32 cm TL), while maintaining constant substrate grain-size. Larger fish used lower cycle frequencies and took longer to bury, but overall burial performance was maintained (~100% coverage). To test the effect of particle size on burial performance, individuals of similar lengths (5.7-8.1 cm TL) were presented with different substrate sizes (0.125-0.710 mm). Particle size did not affect cycle frequency or time to burial, but fish did not achieve 100% coverage with the largest particles because they could not fluidize this substrate. Taken together, these results suggest that both body size and substrate grain size can potentially limit the ability of flatfishes to bury: a very large fish (>150 cm) may move too slowly to fluidize all but the smallest substrate particles and some particles are simply too large for smaller individuals to fluidize

Data from: Functional coupling in the evolution of suction feeding and gill ventilation of sculpins (Perciformes: Cottoidei)

Suction feeding and gill ventilation in teleosts are functionally coupled, meaning that there is an overlap in the structures involved with both functions. Functional coupling is one type of morphological integration, a term that broadly refers to any covariation, correlation, or coordination among structures. Suction feeding and gill ventilation exhibit other types of morphological integration, including functional coordination (a tendency of structures to work together to perform a function) and evolutionary integration (a tendency of structures to covary in size or shape across evolutionary history). Functional coupling, functional coordination, and evolutionary integration have each been proposed to limit morphological diversification to some extent. Yet teleosts show extraordinary cranial diversity, suggesting that there are mechanisms within some teleost clades that promote morphological diversification, even within the highly integrated suction feeding and gill ventilatory systems. To investigate this, we quantified evolutionary integration among four mechanical units associated with suction feeding and gill ventilation in a diverse clade of benthic, primarily suction-feeding fishes (Cottoidei; sculpins and relatives). We reconstructed cottoid phylogeny using molecular data from 108 species, and obtained 24 linear measurements of four mechanical units (jaws, hyoid, opercular bones, and branchiostegal rays) from micro-CT reconstructions of 44 cottoids and one outgroup taxon. We tested for evolutionary correlation and covariation among the four mechanical units using phylogenetically corrected principal component analysis to reduce the dimensionality of measurements for each unit, followed by correlating phylogenetically independent contrasts and computing phylogenetic generalized least squares models from the first principle component axis of each of the four mechanical units. The jaws, opercular bones, and branchiostegal rays show evolutionary integration, but the hyoid is not positively integrated with these units. To examine these results in an ecomorphological context, we used published ecological data in phylogenetic ANOVA models to demonstrate that the jaw is larger in fishes that eat elusive or grasping prey (e.g., prey that can easily escape or cling to the substrate) and that the hyoid is smaller in intertidal and hypoxia-tolerant sculpins. Within Cottoidei, the relatively independent evolution of the hyoid likely has reduced limitations on morphological evolution within the highly morphologically integrated suction feeding and gill ventilatory systems

Trees, data files, and R script

besttree_icz022.tree = maximum clade credibility tree from best MrBayes run; cottoidei.run1.t = posterior distribution of trees from best MrBayes run; Functional Couping Stats icz022.R = R Script for all analyses in this study; ctdata_icz022.txt = morphological measurements from micro-CT scans of 45 species; CSV files = ecological dat

Wear cutting ability

Wear cutting abilit

Scaling of fish length

Scaling of fish lengt