Patterns and processes in amphibious fish: biomechanics and neural control of fish terrestrial locomotion.

Amphibiousness in fishes spans the actinopterygian tree from the earliest to the most recently derived species. The land environment requires locomotor force production different from that in water, and a diversity of locomotor modes have evolved across the actinopterygian tree. To compare locomotor mode between species, we mapped biomechanical traits on an established amphibious fish phylogeny. Although the diversity of fish that can move over land is large, we noted several patterns, including the rarity of morphological and locomotor specialization, correlations between body shape and locomotor mode, and an overall tendency for amphibious fish to be small. We suggest two idealized empirical metrics to consider when gauging terrestrial 'success' in fishes and discuss patterns of terrestriality in fishes considering biomechanical scaling, physical consequences of shape, and tissue plasticity. Finally, we suggest four ways in which neural control could change in response to a novel environment, highlighting the importance and challenges of deciphering when these control mechanisms are used. We aim to provide an overview of the diversity of successful amphibious locomotion strategies and suggest several frameworks that can guide the study of amphibious fish and their locomotion.

Future Tail Tales: A Forward-Looking, Integrative Perspective on Tail Research.

Synopsis Tails are a defining characteristic of chordates and show enormous diversity in function and shape. Although chordate tails share a common evolutionary and genetic-developmental origin, tails are extremely versatile in morphology and function. For example, tails can be short or long, thin or thick, and feathered or spiked, and they can be used for propulsion, communication, or balancing, and they mediate in predator-prey outcomes. Depending on the species of animal the tail is attached to, it can have extraordinarily multi-functional purposes. Despite its morphological diversity and broad functional roles, tails have not received similar scientific attention as, for example, the paired appendages such as legs or fins. This forward-looking review article is a first step toward interdisciplinary scientific synthesis in tail research. We discuss the importance of tail research in relation to five topics: (1) evolution and development, (2) regeneration, (3) functional morphology, (4) sensorimotor control, and (5) computational and physical models. Within each of these areas, we highlight areas of research and combinations of long-standing and new experimental approaches to move the field of tail research forward. To best advance a holistic understanding of tail evolution and function, it is imperative to embrace an interdisciplinary approach, re-integrating traditionally siloed fields around discussions on tail-related research.

Swimming and defence: competing needs across ontogeny in armoured fishes (Agonidae).

Biological armours are potent model systems for understanding the complex series of competing demands on protective exoskeletons; after all, armoured organisms are the product of millions of years of refined engineering under the harshest conditions. Fishes are no strangers to armour, with various types of armour plating common to the 400-500 Myr of evolution in both jawed and jawless fishes. Here, we focus on the poachers (Agonidae), a family of armoured fishes native to temperate waters of the Pacific rim. We examined armour morphology, body stiffness and swimming performance in the northern spearnose poacher (Agonopsis vulsa) over ontogeny. As juveniles, these fishes make frequent nocturnal forays into the water column in search of food, while heavily armoured adults are bound to the benthos. Most armour dimensions and density increase with body length, as does body stiffness. Juvenile poachers have enlarged spines on their armour whereas adults invest more mineral in armour plate bases. Adults are stiffer and accelerate faster than juveniles with an anguilliform swimming mode. Subadults more closely approximate adults more than smaller juveniles, with regards to both swimming and armour mechanics. Poacher armour serves multiple functions over ontogeny, from facilitating locomotion, slowing sinking and providing defence.

The Natural Historian's Guide to the CT Galaxy: Step-by-Step Instructions for Preparing and Analyzing Computed Tomographic (CT) Data Using Cross-Platform, Open Access Software.

The decreasing cost of acquiring computed tomographic (CT) data has fueled a global effort to digitize the anatomy of museum specimens. This effort has produced a wealth of open access digital three-dimensional (3D) models of anatomy available to anyone with access to the Internet. The potential applications of these data are broad, ranging from 3D printing for purely educational purposes to the development of highly advanced biomechanical models of anatomical structures. However, while virtually anyone can access these digital data, relatively few have the training to easily derive a desirable product (e.g., a 3D visualization of an anatomical structure) from them. Here, we present a workflow based on free, open source, cross-platform software for processing CT data. We provide step-by-step instructions that start with acquiring CT data from a new reconstruction or an open access repository, and progress through visualizing, measuring, landmarking, and constructing digital 3D models of anatomical structures. We also include instructions for digital dissection, data reduction, and exporting data for use in downstream applications such as 3D printing. Finally, we provide Supplementary Videos and workflows that demonstrate how the workflow facilitates five specific applications: measuring functional traits associated with feeding, digitally isolating anatomical structures, isolating regions of interest using semi-automated segmentation, collecting data with simple visual tools, and reducing file size and converting file type of a 3D model.

PORTUGUÊS (PORTUGUESE)  O Guia da Galáxia da Tomografia Computadorizada para um Biólogo: instruções passo a passo para preparar e analisar dados tomográficos usando um software gratuito de acesso aberto  Thaddaeus J. Buser, Olivia F. Boyd, Álvaro Cortés, Cassandra M. Donatelli, Matthew A. Kolmann, Jennifer L. Luparell, Janne A. Pfeiffenberger, Brian L. Sidlauskas, Adam P. Summers  RESUMOO custo decrescente da obtenção de dados de Tomografia Computadorizada (TC) alimentou um esforço global para digitalizar espécimes depositados em museus. Esse esforço produziu uma grande variedade de modelos digitais 3 D com dados de anatomia, disponíveis para qualquer pessoa com acesso à Internet. As aplicações potenciais desses dados são amplas, desde a impressão 3 D para fins puramente educacionais, até o desenvolvimento de modelos biomecânicos de estruturas anatômicas altamente avançados. No entanto, enquanto praticamente qualquer pessoa pode acessar esses dados digitais, relativamente poucos têm o treinamento para obter facilmente um produto de interesse (por exemplo, uma visualização 3 D de uma estrutura anatômica). Aqui, apresentamos um tutorial baseado em um software gratuito de código aberto e multiplataforma para o processamento de dados de TC. Fornecemos instruções passo a passo que começam com a obtenção de dados de TC a partir de uma nova reconstrução ou num repositório de acesso aberto, e progredimos através da visualização, medição, marca de referência e construção de modelos digitais 3 D de estruturas anatômicas. Também incluímos instruções para dissecação digital, redução de dados e exportação de dados para uso em aplicativos posteriores, como os de impressoras 3 D. Por fim, fornecemos vídeos e tutoriais suplementares que demonstram como o tutorial facilita cinco aplicações específicas: medir características funcionais associadas à alimentação, isolar estruturas anatômicas digitalmente, isolar regiões de interesse usando segmentação semi-automática, coletar dados com ferramentas visuais simples, e reduzir o tamanho de arquivo e converter o tipo de arquivo do modelo 3 D.

FRANÇAIS (FRENCH)  Guide de l'historien de la nature à travers la galaxie TDM: instructions étape par étape pour la préparation et l'analyse de données tomodensitométrique (TDM) à l'aide d'un logiciel à accès ouvert multiplateforme Thaddaeus J. Buser, Olivia F. Boyd, Álvaro Cortés, Cassandra M. Donatelli, Matthew A. Kolmann, Jennifer L. Luparell, Janne A. Pfeiffenberger, Brian L. Sidlauskas, Adam P. Summers RÉSUMÉLe coût décroissant de l'acquisition de données tomodensitométriques (TDM) a alimenté un effort mondial pour numériser l'anatomie des spécimens de musée. Cet effort a produit une multitude de modèles d'anatomie numérique 3 D en accès libre accessibles à tous ceux qui ont accès à Internet. Les applications potentielles de ces données sont vastes, allant de l'impression 3 D à des fins purement pédagogiques au développement de modèles biomécaniques de structures anatomiques très avancés. Cependant, alors que pratiquement tout le monde peut accéder à ces données numériques, relativement peu ont la formation nécessaire pour en tirer facilement un produit intéressant (par exemple, une visualisation 3 D d'une structure anatomique). Ici, nous présentons un flux de travail basé sur un logiciel gratuit, à accès ouvert et multiplateforme pour le traitement des données TDM. Nous fournissons des instructions étape par étape qui commencent par l'acquisition de données TDM à partir d'une nouvelle reconstruction ou d'un référentiel en accès gratuit, et progressent à travers la visualisation, la mesure, le marquage et la construction de modèles numériques 3 D de structures anatomiques. Nous incluons également des instructions pour la dissection numérique, la réduction des données et l'exportation de données à utiliser dans des applications en aval telles que l'impression 3 D. Enfin, nous proposons des vidéos et des workflows supplémentaires qui montrent comment le workflow facilite cinq applications spécifiques: mesurer les traits fonctionnels associés à l'alimentation, isoler numériquement les structures anatomiques, isoler les régions d'intérêt à l'aide de la segmentation semi-automatisée, collecter des données avec des outils visuels simples, réduire la taille du fichier et convertir le type de fichierd'un modèle 3 D.