Similar Body Shape Research Articles

Bisecting the type series of Leporinus paranensis Garavello and Britski, 1987 (Characiformes, Anostomidae)

The type series of Leporinus paranensis includes two distinct species, one of which is herein described as new. Leporinus paranensis is redescribed based on its holotype, two paratypes, and additional specimens recently sampled in tributaries of the Grande river, in the north portion of the upper Paraná basin in Brazil. A new species of Leporinus is described based on specimens collected in all major tributaries of the upper Paraná basin in Brazil, and tributaries of the Paraná river in Paraguay. Both species share the presence of three unicuspid teeth on the premaxillary and four on dentary, terminal mouth and three dark midlateral blotches on the body. The new species is distinguished from L. paranensis based on the number of scale series around the caudal peduncle (12 vs. 16). The variation in the body shape of both species were compared through a Principal Component Analysis and showed that they share a similar body shape. Species delimitation analyses using DNA Barcode were applied to compare samples of the new species to congeners and corroborated the uniqueness of the new species. In addition, molecular data revealed that L. bahiensis, L. octofasciatus, and L. taeniatus are possibly closely related to the new species. The conservation status of L. paranensis and the new species are discussed using the IUCN criteria.

An analysis of indices and ratios in anthropometric body measurements among team sports athletes

Background: Physical indices and proportions based on anthropometry are crucial for determining the performance of players in team sports. The study aims to analyze the anthropometric status, body mass and shape indices, including waist-to-hip and height ratios, among athletes from different team sports.
 Methods: Study involved 135 male team-sport athletes specializing in basketball, handball, and volleyball, with 45 players in each sport. Researchers collected anthropometric data, including chronological age (CA), height (Ht), weight (Wt), body mass index (BMI), waist circumferences (WC) and hip circumferences (HC), waist-hip ratio (WHR), waist-height ratio (WHtR), and a body shape index (ABSI). To compare variables across groups, descriptive statistics and one-way ANOVA with LSD post-hoc tests used. Relationships within each group were examined using correlation analysis.
 Results: The ANOVA findings indicated f values (2, 132) for CA at 0.57, p=0.57, BMI at 0.59, p=0.56, WC at 2.10, p=0.13, WHR at 1.37, p=0.27, and ABSI at 1.41, p=0.25, respectively, revealing no significant disparities among the groups. Conversely, Ht at 13.36, p=0.00, Wt at 5.74, p=0.00, HC at 6.33, p=0.00, and WHtR at 3.60, p=0.03, respectively, highlighted significant variations between the groups. Furthermore, the correlation of BMI, WC, HC, WHR, WHtR, and ABSI in each group showed a strong positive correlation (p<0.01).
 Conclusions: Athletes in team sports were found to have similar body mass and shape indices, including ratios for WHR, while the WHtR ratio showed significant variations among the groups. Despite these differences, measures of athletes’ health metrics across these sports remain within safe, normal ranges.

Declining populations of Astacus astacus drag European Branchiobdella parasita (Annelida: Clitellata) ectosymbionts to serious biodiversity loss

Branchiobdella parasita is specific ectosymbiont of European freshwater crayfish, including endangered noble crayfish (Astacus astacus). Although numerous information on distribution, biology or ecology were reported, genetic structure of B. parasita in European crayfish populations was not studied truthfully. The available molecular data include only cytochrome oxidase subunit I (COI) barcodes of B. parasita coexisting with noble crayfish in Alpine freshwaters in Austria, as well as stone crayfish (Austropotamobius torrentium) and white-clawed crayfish (Austropotamobius pallipes) in Balkan region. Here we report first genetic diversity and haplotype richness analysis of B. parasita populations on a pan-European scale. Specimens (n = 41) were collected from female noble crayfish from three lakes in northwest Poland (Kołtki Małe, Rosko Duże, Skrzynki Małe) and Elkenrother Weiher Lake in southwest Germany, high-quality COI barcodes were obtained and analysed against existing genetic data. The analysed populations were haplotype rich (h = 23) and had high COI haplotype diversity (Hd = 0.8988, I = 1.4554). Our results indicate that diversification rate of European B. parasita populations highly depends on habitat quality, its connection with surface waters and hosts species and mobility. We revealed that Central European populations inhabiting noble crayfish show significant genetic relationship, presenting common ancestral haplotypes and at the same time high genetic divergence from Balkan populations. Based on our results we suggest that ‘parasita-complex’ of phylogenetically related species with similar body shape and structure of chitin jaws, but with differentiating anatomical structure details are present across the continent.

A Stream Function Smoothing Method for the Design of MRI Gradient Coils on Non-Developable Surfaces.

Insert gradient coils with similar imaging body shapes typically have smaller dimensions and higher spatial efficiency. This often allows the gradient coils the achievement of stronger and faster gradient fields. Thus, improving existing methods to make them applicable to the design of MRI gradient coils on complex surfaces has also become a challenge. This article proposes an algorithm that smooths the implicitly expressed stream function based on the intrinsic surface Laplace-Beltrami operator. This algorithm can be used to simplify the design procedure of MRI gradient coils on non-developable surfaces. The following steps are performed by the proposed algorithm: an initial design of the stream function configuration, extraction of the surface mesh, discretization of the surface smoothing operator, and a smoothing of the contour lines. To evaluate the quality of the smoothed streamline configuration, several technical parameter metrics-including magnetic field accuracy, coil power consumption, theoretical minimum wire spacing, and the maximum curvature of the contour lines-were evaluated. The proposed method was successfully validated in a design gradient coil on both developable and non-developable surfaces. All examples evolved from an initial value with a locally non-smooth and complex topological configuration to a smooth result while maintaining high magnetic field accuracy.

FishSeg: 3D Fish Tracking Using Mask R-CNN in Large Ethohydraulic Flumes

To study the fish behavioral response to up- and downstream fish passage structures, live-fish tests are conducted in large flumes in various laboratories around the world. The use of multiple fisheye cameras to cover the full width and length of a flume, low color contrast between fish and flume bottom and non-uniform illumination leading to fish shadows, air bubbles wrongly identified as fish as well as fish being partially hidden behind each other are the main challenges for video-based fish tracking. This study improves an existing open-source fish tracking code to better address these issues by using a modified Mask Regional-Convolutional Neural Network (Mask R-CNN) as a tracking method. The developed workflow, FishSeg, consists of four parts: (1) stereo camera calibration, (2) background subtraction, (3) multi-fish tracking using Mask R-CNN, and (4) 3D conversion to flume coordinates. The Mask R-CNN model was trained and validated with datasets manually annotated from background subtracted videos from the live-fish tests. Brown trout and European eel were selected as target fish species to evaluate the performance of FishSeg with different types of body shapes and sizes. Comparison with the previous method illustrates that the tracks generated by FishSeg are about three times more continuous with higher accuracy. Furthermore, the code runs more stable since fish shadows and air bubbles are not misidentified as fish. The trout and eel models produced from FishSeg have mean Average Precisions (mAPs) of 0.837 and 0.876, respectively. Comparisons of mAPs with other R-CNN-based models show the reliability of FishSeg with a small training dataset. FishSeg is a ready-to-use open-source code for tracking any fish species with similar body shapes as trout and eel, and further fish shapes can be added with moderate effort. The generated fish tracks allow researchers to analyze the fish behavior in detail, even in large experimental facilities.

BARC: Breed-Augmented Regression Using Classification for 3D Dog Reconstruction from Images

The goal of this work is to reconstruct 3D dogs from monocular images. We take a model-based approach, where we estimate the shape and pose parameters of a 3D articulated shape model for dogs. We consider dogs as they constitute a challenging problem, given they are highly articulated and come in a variety of shapes and appearances. Recent work has considered a similar task using the multi-animal SMAL model, with additional limb scale parameters, obtaining reconstructions that are limited in terms of realism. Like previous work, we observe that the original SMAL model is not expressive enough to represent dogs of many different breeds. Moreover, we make the hypothesis that the supervision signal used to train the network, that is 2D keypoints and silhouettes, is not sufficient to learn a regressor that can distinguish between the large variety of dog breeds. We therefore go beyond previous work in two important ways. First, we modify the SMAL shape space to be more appropriate for representing dog shape. Second, we formulate novel losses that exploit information about dog breeds. In particular, we exploit the fact that dogs of the same breed have similar body shapes. We formulate a novel breed similarity loss, consisting of two parts: One term is a triplet loss, that encourages the shape of dogs from the same breed to be more similar than dogs of different breeds. The second one is a breed classification loss. With our approach we obtain 3D dogs that, compared to previous work, are quantitatively better in terms of 2D reconstruction, and significantly better according to subjective and quantitative 3D evaluations. Our work shows that a-priori side information about similarity of shape and appearance, as provided by breed labels, can help to compensate for the lack of 3D training data. This concept may be applicable to other animal species or groups of species. We call our method BARC (Breed-Augmented Regression using Classification). Our code is publicly available for research purposes at https://barc.is.tue.mpg.de/.

Is the hyoid a constraint on innovation? A study in convergence driving feeding in fish-shaped marine tetrapods

AbstractThe hyoid apparatus is essential for underwater feeding in marine tetrapods, but it is unclear whether this complex has evolved as convergently as other traits, such as dentition or locomotion. Here we compare the ossified hyoid elements in ophthalmosaurid ichthyosaurs and odontocete cetaceans, two groups with an overall similar body shape, to understand whether the hyoid elements show any signs of convergence in the context of feeding. We examined three types of data (size, morphology, and internal bone microstructure) in ophthalmosaurid and odontocete taxa in which these elements are preserved. Our data show that ichthyosaurs never experienced a shift in feeding mode, which might indicate that their hyoid apparatus never adapted to suction feeding. Also, the internal microstructure of the two animal groups differs; where the odontocetes have an overall less compact structure, ophthalmosaurid ichthyosaurs have cancellous inner cones in an outer, more compact sheath. These differences are likely explained as biomechanical adaptations to different feeding modes. Thus, the hyoid changed less and acted more as a constraint for feeding innovation in ichthyosaurs compared with cetaceans, and through a much longer time span (more than 150 Myr).

Exploring modality-shared appearance features and modality-invariant relation features for cross-modality person Re-IDentification

Most existing cross-modality person Re-IDentification works rely on discriminative modality-shared features for reducing cross-modality variations and intra-modality variations. Despite their preliminary success, such modality-shared appearance features cannot capture enough modality-invariant discriminative information due to a massive discrepancy between RGB and IR images. To address this issue, on top of appearance features, we further capture the modality-invariant relations among different person parts (referred to as modality-invariant relation features), which help to identify persons with similar appearances but different body shapes. To this end, a Multi-level Two-streamed Modality-shared Feature Extraction (MTMFE) sub-network is designed, where the modality-shared appearance features and modality-invariant relation features are first extracted in a shared 2D feature space and a shared 3D feature space, respectively. The two features are then fused into the final modality-shared features such that both cross-modality variations and intra-modality variations can be reduced. Besides, a novel cross-modality center alignment loss is proposed to further reduce the cross-modality variations. Experimental results on several benchmark datasets demonstrate that our proposed method exceeds state-of-the-art algorithms by a wide margin.

Testing hypotheses of habitat use and temporal activity in relation to body plan in a Mediterranean lizard community

A body plan (bauplan) is a suite of morphological characters shared by phylogenetically related animals at some point during their development. Despite its value, the bauplan concept is still rarely employed to characterize functional groups in community ecology. Here, we examine habitat use and spatio-temporal activity correlates of an entire seven-species community of lizards with different bauplans. The study was carried out in three locations in central Italy, encompassing a complex landscape with a patchy mosaic of a wide variety of habitats and microclimates. We tested four hypotheses regarding niche breadth, habitat use, and activity patterns. The first hypothesis, niche complementarity, in which species with similar body shapes should non-randomly partition available habitats, was not supported. By contrast, the hypotheses that larger bodied species should have a wider niche breadth, that slower species should inhabit habitat types of higher cover, and species inhabiting open sunny habitats should exhibit more seasonally variable activity patterns, were all supported by the data. Sympatric lizard communities in our study area were clearly organized by autecological constraints and eco-physiological attributes.

Phenotypic Convergence in Sea Bass (Dicentrarchus labrax) Escaping From Fish Farms: The Onset of Feralization?

The impact of fish escaping from fish farms may depend on the extent to which escapees adapt to the natural environment, resemble wild conspecifics, and become feral. Yet, little is known about the process of feralization in marine fish. We examined phenotypic changes in body shape, body condition, and scale growth profiles of sea bass escaping from fish farms in the Canary Islands and quantified the extent to which escapees had diverged from farmed conspecifics. Most feral sea bass had sizes that overlapped with those of farmed fish, indicating that they had escaped throughout the production cycle. However, 29% of escapees were larger than the maximum size at harvesting, indicating growth in the wild. Analysis of scale growth profiles showed that some escapees had grown in the wild as fast as cultured fish, albeit at more variable growth rates. Feral sea bass tended to converge towards a similar body shape, having more streamlined bodies, lower body condition, and lower hepatosomatic indices (HSI) than fish in cages. Although our study cannot discriminate between phenotypic plasticity and differential mortality of escapees, we interpret phenotypic convergence as the likely result of a period of initial starvation, phenotypic plasticity, and selection against maladapted phenotypes. Our results warn against the risks of rearing sea bass in open-net cages and suggest that sea bass escapees could pose a threat to shallow coastal assemblages, particularly in areas where the species is not naturally found.

Effects of wave-driven water flow on the fast-start escape response of juvenile coral reef damselfishes.

Fish often evade predators with a fast-start escape response. Studies typically examine this behaviour in still water despite water motion being an inherent feature of aquatic ecosystems. In shallow habitats, waves create complex flows that likely influence escape performance, particularly in small fishes with low absolute swimming speeds relative to environmental flows. I examined how wave-driven water flow affects the behaviour and kinematics of escape responses in juveniles of three coral reef damselfishes (Pomacentridae) with different body morphologies. Tropical damselfishes have similar fin and body shapes during early development, with the exception of body depth, a trait deemed important for postural control and stability. Wave-driven flow increased response latency in two of the three species tested: fish with a fusiform body responded 2.9 times slower in wave-driven flow than in still water, whereas this difference was less pronounced in fish with an intermediate body depth (1.9 times slower response) and absent in fish with a laterally compressed body. The effect of wave-driven flow on swimming performance (cumulative escape distance and turning rate) was variable and depended on the timing and trajectory of escape responses in relation to the wave phase. Given intense predation pressure on juvenile coral reef fishes during settlement, interspecific differences in how wave-driven flow affects their ability to escape predators could influence the distribution and abundance of species across spatial and temporal scales.

Rise and fall of †Pycnodontiformes: Diversity, competition and extinction of a successful fish clade.

†Pycnodontiformes was a successful lineage of primarily marine fishes that broadly diversified during the Mesozoic. They possessed a wide variety of body shapes and were adapted to a broad range of food sources. Two other neopterygian clades possessing similar ecological adaptations in both body morphology (†Dapediiformes) and dentition (Ginglymodi) also occurred in Mesozoic seas. Although these groups occupied the same marine ecosystems, the role that competitive exclusion and niche partitioning played in their ability to survive alongside each other remains unknown. Using geometric morphometrics on both the lower jaw (as constraint for feeding adaptation) and body shape (as constraint for habitat adaptation), we show that while dapediiforms and ginglymodians occupy similar lower jaw morphospace, pycnodontiforms are completely separate. Separation also occurs between the clades in body shape so that competition reduction between pycnodontiforms and the other two clades would have resulted in niche partitioning. Competition within pycnodontiforms seemingly was reduced further by evolving different feeding strategies as shown by disparate jaw shapes that also indicate high levels of plasticity. Acanthomorpha was a teleostean clade that evolved later in the Mesozoic and which has been regarded as implicated in driving the pycnodontiforms to extinction. Although they share similar body shapes, no coeval acanthomorphs had similar jaw shapes or dentitions for dealing with hard prey like pycnodontiforms do and so their success being a factor in pycnodontiform extinction is unlikely. Sea surface temperature and eustatic variations also had no impact on pycnodontiform diversity patterns according to our results. Conversely, the occurrence and number of available reefs and hardgrounds as habitats through time seems to be the main factor in pycnodontiform success. Decline in such habitats during the Late Cretaceous and Palaeogene might have had deleterious consequences for pycnodontiform diversity. Acanthomorphs occupied the niches of pycnodontiforms during the terminal phase of their existence.

Deciphering species-group taxonomic complexity of common, Barbodes binotatus and saddle barbs, B. banksi in Peninsular Malaysia

Correct assessment of freshwater fishes depends on the most recent taxonomic nomenclature and accurate identification. The existing of the complex between closely related species is one of the prominent issues that sometimes poorly addressed that leads to misidentification of the species and inaccurate diversity measurement. This study addressed the issue through morphometrics methods, to correctly evaluate the diversity of freshwater fish within species group of genus Barbodes , i.e., B. binotatus and B. banksi . In examining species complex of B. binotatus and B. banksi , traditional and landmark-based geometric morphometrics methods were applied. Traditional morphometric displayed characters that distinguished both species were generally located at the anterior part of the body, and specifically in the cephalic area of the fish. Landmark-based geometric morphometric revealed a highly similar body shape on both species. Variations within both species were subtle and could not be significantly distinguished by both methods. The overall outcomes of this study suggest that in order to achieve a proper assessment to freshwater fishes, one need to solve the identification problems in species complex. This effort could consequently lead to a better understanding of freshwater fish status, for a better conservation plan and management.

Size and shape assortative mating in Japanese beetles (Popilliajaponica)

Assortative mating is hypothesized to be a product of sexual selection, mating constraints, or temporal autocorrelation. I test these hypotheses in the Japanese beetle (Popillia japonica Newman, 1841), a sexually size dimorphic invasive insect pest in North America, by measuring the size and shape of bodies and wings of pair members in a wild population. Because male P. japonica prefer to mate with larger females and larger males outcompete rivals for mating opportunities, sexual selection is expected to produce size-related assortative mating. The current study did not support this hypothesis. The mating constraints hypothesis was also not supported because beetle pairs did not have similar body shapes. I, however, did find support for the temporal autocorrelation hypothesis as the wing size and shape of pair members were significantly correlated. This mating pattern likely arises due to individuals with larger and more slender wings arriving earlier at aggregation sites and pairing according to their arrival sequence. Although I found less support for the sexual selection hypothesis, I argue that mate choice might play an important, but secondary, role to temporal autocorrelation in explaining assortative mating in Japanese beetles.

Using 3D‐digital photogrammetry to examine scaling of the body axis in burrowing skinks

Three-dimensional (3D) modeling techniques have been increasingly utilized across disciplines for the visualization and analysis of complex structures. We employ 3D-digital photogrammetry for understanding the scaling of the body axis of 12 species of scincid lizards in the genus Brachymeles. These skinks represent a diverse radiation which shows tremendous variation in body size and degree of axial elongation. Because of the complex nature of the body axis, 3D-methods are important for understanding how the body axis evolves. 3D-digital photogrammetry presents a flexible, inexpensive, and portable system for the reconstruction of biological forms. As body size increased among species, the cross-sectional area and circumference of the head and other portions of the body axis increased isometrically, which indicates that species of differing sizes possess proportionally similar head and body shapes. These results suggest that there are no substantial head and body shape changes with body size among the sampled species, but further comparative studies with larger sample sizes and functional studies of size and morphology effects on burrowing or above-ground locomotion are needed.

Sexually dimorphic characters and shared aposematic patterns mislead the morphology-based classification of the Lycini (Coleoptera: Lycidae)

AbstractThe Lycini (Elateroidea: Lycidae) contains > 400 species placed in four typologically based genera and numerous subgenera. We assembled a mito-ribosomal dataset representing ~100 species from the whole range and recovered a phylogeny rejecting Lycus and Lycostomus as polyphyletic assemblages. The male-specific wide elytra and elytral thorns are identified in unrelated Neolycus and Lycus. The morphological similarity based on sexual dimorphism and aposematic patterns defined terminal clades and misled the genus-rank classification. We delimit Neolycus, Rhyncheros reinst. name (= Thoracocalon syn. nov. = Lyconotus syn. nov.), LipernesLycostomus, Haplolycus and Lycus. Demosis and six subgenera of Lycus are synonymized with Lycus. Celiasis Laporte, 1840 is kept in the classification as a nomen dubium until any specimen is available. The deep lineages are known from the Americas and Asia. Africa was colonized by Lycus and Haplolycus. Each specific aposematic pattern occurs in a limited range, and the similar body shape and coloration evolved in unrelated sympatrically occurring lineages. High intraspecific polymorphism is putatively a result of the adaptation of various populations to local mimetic assemblages. Therefore, the delimitation of many phenotypically diverse species should be investigated.

Collegiate female athletes\u2019 body image and clothing behaviors

This study investigated the body image experiences unique to collegiate female athletes in relation to their apparel wear. Female athletes (n = 36) participated in interview sessions, 3D body scanning, and photography of garment fit, and the Multidimensional Body-Self Relations Questionnaire (MBSRQ). Through Qualtrics, the MBSRQ was distributed to female college students nationwide, to obtain a larger participant pool (Lean sport athletes (n = 36), non-lean sport athletes (n = 42) and non-athletes (n = 101). Results indicated that both sports groups were most influenced by sport specific body ideals. Correlation of body image and athletic uniforms was more influenced by the fit of the uniform than by the categorization of the sport. Both lean and non-lean sport group participants expressed dissatisfaction in pant fit. 3D body scans revealed similar body proportions and shape between sports groups. MBSRQ results indicated no significant difference between sports groups but higher body image scores in comparison to non-athletes.

<p class="Body"><strong>Molecular and ontogeny studies clarify systematic status of <em>Chamobates borealis </em>(Acari, Oribatida, Chamobatidae): an integrated taxonomy approach</strong></p>

Chamobates borealis (Trägårdh 1902) has been considered by some authors as a junior synonym of Chamobates pusillus (Berlese 1895). In this study we used an integrated taxonomy approach, comparing mitochondrial coding gene COI and morphological ontogeny of these species to clarify their systematic status. The Bayesian inference tree based on COI sequences of C. borealis and C. pusillus, as well as C. birulai (Kulczyński 1902), C. bispinosus Mahunka, 1987, C. cuspidatus (Michael 1884) and C. rastratus (Hull 1914) separated all these species. In terms of the morphology, the adults of C. borealis and C. pusillus have similar body size and shape, thin aggenital setae and two lateral teeth on the rostrum, but C. borealis has the medial incision between these teeth, which is absent in C. pusillus. The adults of these species differ also from each other by the shape of bothridial setae, size of area porose Aa, location of seta lm and lyrifissure im, and the shape of most setae on the hysterosoma. The morphological ontogeny of these species is similar, but the larva and nymphs of C. borealis differ from those of C. pusillus by the length of some prodorsal and gastronotal setae, and the nymphs of C. borealis have a humeral organ, which is absent in C. pusillus. The presence of a humeral organ in some Chamobates species supports a clade inferred by COI sequence data.

Body shape separates guilds of rheophilic herbivores (Myleinae: Serrasalmidae) better than feeding morphology

Herbivorous fishes feed on stems, leaves, flowers, seeds, fruits, and nuts of diverse aquatic plants, as well as algae. Pacus are the herbivorous cousins of piranhas and consume a myriad of diets comprised of these plant products, but a few species are phytophages, herbivores that feed almost exclusively on rapids-dwelling (rheophilic) riverweed plants from the family Podostemaceae. The degree to which pacus feed on riverweed varies from obligate year-round consumption to strictly seasonal, facultative feeding. Obligate phytophages feed heavily on riverweed and strictly occur in river rapids, while facultative phytophages only consume riverweed during seasons with low flow. Does ecological specialization (diet) beget morphological specialization in the feeding apparatus and/or body shape of phytophages? Under a phylogenetic framework, we used micro-computed tomography (µCT) scanning to compare functional feeding traits among 26 species of serrasalmids, four of which are obligate phytophages. We also compared body shape between pacus using geometric morphometrics to identify potential locomotor adaptations for rheophily. Obligate phytophages have dentitions and slicing jaws well-suited for shearing fleshy plant material relative to other pacus, which are equipped with fruit and seed crushing morphologies. Unrelated obligate phytophages have also converged on a similar body shape that is distinct from sympatric congeneric herbivores. Phytophagy involves more consistent changes to body shape than to feeding morphology, suggesting that body shape has more important ties to diet.

Fish fin physique factor in food preferences

Some fish are built for power, scything sleekly through the water, powered by their tails, while others simply potter around rippling their fins. But, the members of one superfamily, comprising triggerfish and filefish (known collectively as the Balistoidea), are able to switch effortlessly between the distinctive styles: rippling the dorsal and anal fins – located above and below the base of their tails – at low speeds, and switching to beating the tail powerfully to and fro when they shift up the gears for a high-speed swim. Yet, each species performs the switch from low to high speed in subtly different ways. Intrigued by the fishes’ elaborate family tree and distinctive appearance, Andrew George and Mark Westneat from the University of Chicago, USA, wondered which aspects of their fin physique determine when they transition from one swimming mode to the other.Selecting members of the superfamily spanning the entire dynasty, from the orange-spotted filefish (Oxymonacanthus longirostris) to the orange-lined triggerfish (Balistapus undulatus), George filmed and observed the fish as they swam, gradually increasing the flow speed from 5 to 60 cm s−1, until the fish could no longer keep swimming against the water. During that time, he recorded the speed at which the animals stepped up a gear and began to beat their tail fin back and forth. ‘The most difficult part was controlling for variation in the fish's behaviour’, says George, adding how every single filefish initially tried to avoid swimming, by gripping the grill at the front of the tank with their jaws. In addition, George carefully photographed and measured the area and shape of the animals’ body and fins before painstakingly analysing the relationships between each fish's build and swimming performance.Impressively, the fastest fish for its size was the tiny (9 cm long) red-toothed triggerfish (Odonus niger) – which clocked up a speedy 55 cm s−1 – while the more sluggish bristle-tail filefish (Acreichthys tomentosus) and larger whitespotted filefish (Cantherhines macrocerus) trailed in at the more sedate speeds of 30 and 40 cm s−1, respectively. Comparing the swimming styles of the fishes, it was clear that the filefish rarely used their tailfins, preferring to use their dorsal and anal fins up to 94% of the time, while some triggerfish beat their tails almost 60% of the time. And when George compared the shape of the fishes’ fins with their swim speeds, it was clear that those with the triangular fins were able to power swimming at higher speeds than those with rectangular fins.However, the duo was surprised when they realised that the fish with rectangular anal and dorsal fins hit similar top swimming speeds (35–42 cm s−1) to the more powerful-looking fish with triangular anal and dorsal fins before they added in their tail fins. In contrast, the fish with short rounded anal and dorsal fins turned on their tail beat over a wide range of speeds, from the slowest at 21 cm s−1 up to 34 cm s−1. And when they analysed the fishes’ swimming styles relative to their fin sizes, it was clear that those with long chunky anal and dorsal fins rarely use their tail fins, while those with small stubby anal and dorsal fins use their tail fins a significant proportion of the time.But what does this all mean for the fishes’ lifestyles? ‘The ecological pattern that popped out most clearly was that species with similar fin and body shapes tend to eat similar food’, says George, pointing out that fishes with the highest swim speeds tend to consume plankton in fast-flowing water, while slower anal and dorsal fin-propelled fishes recruit their tail fin for a sudden burst of speed when dining on fast-moving fish and octopus snacks.