The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
H. Arthur Woods - One of the best experts on this subject based on the ideXlab platform.
-
Cuticular gas exchange by Antarctic sea spiders
The Journal of Experimental Biology, 2018Co-Authors: Steven J. Lane, Caitlin M. Shishido, Amy L. Moran, Bret W. Tobalske, H. Arthur WoodsAbstract:ABSTRACT Many marine organisms and life stages lack specialized respiratory structures, like gills, and rely instead on Cutaneous Respiration, which they facilitate by having thin integuments. This respiratory mode may limit body size, especially if the integument also functions in support or locomotion. Pycnogonids, or sea spiders, are marine arthropods that lack gills and rely on Cutaneous Respiration but still grow to large sizes. Their cuticle contains pores, which may play a role in gas exchange. Here, we examined alternative paths of gas exchange in sea spiders: (1) oxygen diffuses across pores in the cuticle, a common mechanism in terrestrial eggshells, (2) oxygen diffuses directly across the cuticle, a common mechanism in small aquatic insects, or (3) oxygen diffuses across both pores and cuticle. We examined these possibilities by modeling diffusive oxygen fluxes across all pores in the body of sea spiders and asking whether those fluxes differed from measured metabolic rates. We estimated fluxes across pores using Fick9s law parameterized with measurements of pore morphology and oxygen gradients. Modeled oxygen fluxes through pores closely matched oxygen consumption across a range of body sizes, which means the pores facilitate oxygen diffusion. Furthermore, pore volume scaled hypermetrically with body size, which helps larger species facilitate greater diffusive oxygen fluxes across their cuticle. This likely presents a functional trade-off between gas exchange and structural support, in which the cuticle must be thick enough to prevent buckling due to external forces but porous enough to allow sufficient gas exchange.
-
Upper limits to body size imposed by respiratory-structural trade-offs in Antarctic pycnogonids.
Proceedings. Biological sciences, 2017Co-Authors: Steven J. Lane, Caitlin M. Shishido, Amy L. Moran, Bret W. Tobalske, Claudia P. Arango, H. Arthur WoodsAbstract:Across metazoa, surfaces for respiratory gas exchange are diverse, and the size of those surfaces scales with body size. In vertebrates with lungs and gills, surface area and thickness of the respiratory barrier set upper limits to rates of metabolism. Conversely, some organisms and life stages rely on Cutaneous Respiration, where the respiratory surface (skin, cuticle, eggshell) serves two primary functions: gas exchange and structural support. The surface must be thin and porous enough to transport gases but strong enough to withstand external forces. Here, we measured the scaling of surface area and cuticle thickness in Antarctic pycnogonids, a group that relies on Cutaneous Respiration. Surface area and cuticle thickness scaled isometrically, which may reflect the dual roles of cuticle in gas exchange and structural support. Unlike in vertebrates, the combined scaling of these variables did not match the scaling of metabolism. To resolve this mismatch, larger pycnogonids maintain steeper oxygen gradients and higher effective diffusion coefficients of oxygen in the cuticle. Interactions among scaling components lead to hard upper limits in body size, which pycnogonids could evade only with some other evolutionary innovation in how they exchange gases.
Kate L. Sanders - One of the best experts on this subject based on the ideXlab platform.
-
Novel vascular plexus in the head of a sea snake (Elapidae, Hydrophiinae) revealed by high-resolution computed tomography and histology
Royal Society open science, 2019Co-Authors: Alessandro Palci, Roger S. Seymour, Cao Van Nguyen, Mark Hutchinson, Michael S. Y. Lee, Kate L. SandersAbstract:Novel phenotypes are often linked to major ecological transitions during evolution. Here, we describe for the first time an unusual network of large blood vessels in the head of the sea snake Hydrophis cyanocinctus. MicroCT imaging and histology reveal an intricate modified cephalic vascular network (MCVN) that underlies a broad area of skin between the snout and the roof of the head. It is mostly composed of large veins and sinuses and converges posterodorsally into a large vein (sometimes paired) that penetrates the skull through the parietal bone. Endocranially, this blood vessel leads into the dorsal cerebral sinus, and from there, a pair of large veins depart ventrally to enter the brain. We compare the condition observed in H. cyanocinctus with that of other elapids and discuss the possible functions of this unusual vascular network. Sea snakes have low oxygen partial pressure in their arterial blood that facilitates Cutaneous Respiration, potentially limiting the availability of oxygen to the brain. We conclude that this novel vascular structure draining directly to the brain is a further elaboration of the sea snakes' Cutaneous respiratory anatomy, the most likely function of which is to provide the brain with an additional supply of oxygen.
Steven J. Lane - One of the best experts on this subject based on the ideXlab platform.
-
Cuticular gas exchange by Antarctic sea spiders
The Journal of Experimental Biology, 2018Co-Authors: Steven J. Lane, Caitlin M. Shishido, Amy L. Moran, Bret W. Tobalske, H. Arthur WoodsAbstract:ABSTRACT Many marine organisms and life stages lack specialized respiratory structures, like gills, and rely instead on Cutaneous Respiration, which they facilitate by having thin integuments. This respiratory mode may limit body size, especially if the integument also functions in support or locomotion. Pycnogonids, or sea spiders, are marine arthropods that lack gills and rely on Cutaneous Respiration but still grow to large sizes. Their cuticle contains pores, which may play a role in gas exchange. Here, we examined alternative paths of gas exchange in sea spiders: (1) oxygen diffuses across pores in the cuticle, a common mechanism in terrestrial eggshells, (2) oxygen diffuses directly across the cuticle, a common mechanism in small aquatic insects, or (3) oxygen diffuses across both pores and cuticle. We examined these possibilities by modeling diffusive oxygen fluxes across all pores in the body of sea spiders and asking whether those fluxes differed from measured metabolic rates. We estimated fluxes across pores using Fick9s law parameterized with measurements of pore morphology and oxygen gradients. Modeled oxygen fluxes through pores closely matched oxygen consumption across a range of body sizes, which means the pores facilitate oxygen diffusion. Furthermore, pore volume scaled hypermetrically with body size, which helps larger species facilitate greater diffusive oxygen fluxes across their cuticle. This likely presents a functional trade-off between gas exchange and structural support, in which the cuticle must be thick enough to prevent buckling due to external forces but porous enough to allow sufficient gas exchange.
-
Upper limits to body size imposed by respiratory-structural trade-offs in Antarctic pycnogonids.
Proceedings. Biological sciences, 2017Co-Authors: Steven J. Lane, Caitlin M. Shishido, Amy L. Moran, Bret W. Tobalske, Claudia P. Arango, H. Arthur WoodsAbstract:Across metazoa, surfaces for respiratory gas exchange are diverse, and the size of those surfaces scales with body size. In vertebrates with lungs and gills, surface area and thickness of the respiratory barrier set upper limits to rates of metabolism. Conversely, some organisms and life stages rely on Cutaneous Respiration, where the respiratory surface (skin, cuticle, eggshell) serves two primary functions: gas exchange and structural support. The surface must be thin and porous enough to transport gases but strong enough to withstand external forces. Here, we measured the scaling of surface area and cuticle thickness in Antarctic pycnogonids, a group that relies on Cutaneous Respiration. Surface area and cuticle thickness scaled isometrically, which may reflect the dual roles of cuticle in gas exchange and structural support. Unlike in vertebrates, the combined scaling of these variables did not match the scaling of metabolism. To resolve this mismatch, larger pycnogonids maintain steeper oxygen gradients and higher effective diffusion coefficients of oxygen in the cuticle. Interactions among scaling components lead to hard upper limits in body size, which pycnogonids could evade only with some other evolutionary innovation in how they exchange gases.
-
Figure S1. Scaling coefficients of flux (J), surface area (A), thickness (x), diffusion (Dc), capacitance (β), and the oxygen gradient (ΔPO2). from Upper limits to body size imposed by respiratory-structural trade-offs in Antarctic pycnogonids
2017Co-Authors: Steven J. Lane, Caitlin M. Shishido, Amy L. Moran, Bret W. Tobalske, Claudia P. Arango, Arthur H. WoodsAbstract:Scaling coefficients of flux (J), surface area (A), thickness (x), diffusion (Dc), capacitance (β), and the oxygen gradient (ΔPO2). Coloured lines correspond to coloured variables within Fick's law (eq. 3 and displayed on each graph). The exponents within the equation are equal to the scaling coefficient from the associated figure. A) Fick's law described in terms of scaling coefficients from Gillooly et al. (2016). In vertebrates, Dc, β, and ΔPO2 do not scale with body size and changes in A and x are sufficient to meet oxygen demands (i.e., 0.89 – 0.1 = 0.79). B-D) Hypothesized scaling coefficients of animals relying on Cutaneous Respiration. Slopes of all Fick variables, when added up following Fick's equation, should be equivalent to scaling of MR (null expectation, b = 0.75). A and x are hypothesized to scale with geometric isometry (b = 0.66 and 0.33, respectively), because cuticle provides structural support. In contrast to vertebrates, either Dc (B), ΔPO2 (C), or both (D) must scale positively to meet the increased oxygen demands of larger animals. Capacitance (β) is not expected to vary with body size as it is only dependent on the temperature and type of medium
Roger S. Seymour - One of the best experts on this subject based on the ideXlab platform.
-
Novel vascular plexus in the head of a sea snake (Elapidae, Hydrophiinae) revealed by high-resolution computed tomography and histology
Royal Society open science, 2019Co-Authors: Alessandro Palci, Roger S. Seymour, Cao Van Nguyen, Mark Hutchinson, Michael S. Y. Lee, Kate L. SandersAbstract:Novel phenotypes are often linked to major ecological transitions during evolution. Here, we describe for the first time an unusual network of large blood vessels in the head of the sea snake Hydrophis cyanocinctus. MicroCT imaging and histology reveal an intricate modified cephalic vascular network (MCVN) that underlies a broad area of skin between the snout and the roof of the head. It is mostly composed of large veins and sinuses and converges posterodorsally into a large vein (sometimes paired) that penetrates the skull through the parietal bone. Endocranially, this blood vessel leads into the dorsal cerebral sinus, and from there, a pair of large veins depart ventrally to enter the brain. We compare the condition observed in H. cyanocinctus with that of other elapids and discuss the possible functions of this unusual vascular network. Sea snakes have low oxygen partial pressure in their arterial blood that facilitates Cutaneous Respiration, potentially limiting the availability of oxygen to the brain. We conclude that this novel vascular structure draining directly to the brain is a further elaboration of the sea snakes' Cutaneous respiratory anatomy, the most likely function of which is to provide the brain with an additional supply of oxygen.
-
Cutaneous Respiration by diving beetles from underground aquifers of Western Australia (Coleoptera: Dytiscidae).
The Journal of Experimental Biology, 2019Co-Authors: Karl K. Jones, Steven J. B. Cooper, Roger S. SeymourAbstract:ABSTRACT Insects have a gas-filled respiratory system, which provides a challenge for those that have become aquatic secondarily. Diving beetles (Dytiscidae) use bubbles on the surface of their bodies to supply O2 for their dives and passively gain O2 from the water. However, these bubbles usually require replenishment at the water9s surface. A highly diverse assemblage of subterranean dytiscids has evolved in isolated calcrete aquifers of Western Australia with limited/no access to an air–water interface, raising the question of how they are able to respire. We explored the hypothesis that they use Cutaneous Respiration by studying the mode of Respiration in three subterranean dytiscid species from two isolated aquifers. The three beetle species consume O2 directly from the water, but they lack structures on their bodies that could have respiratory function. They also have a lower metabolic rate than other insects. O2 boundary layers surrounding the beetles are present, indicating that O2 diffuses into the surface of their bodies via Cutaneous Respiration. Cuticle thickness measurements and other experimental results were incorporated into a mathematical model to understand whether Cutaneous Respiration limits beetle size. The model indicates that the cuticle contributes considerably to resistance in the O2 cascade. As the beetles become larger, their metabolic scope narrows, potentially limiting their ability to allocate energy to mating, foraging and development at sizes above approximately 5 mg. However, the ability of these beetles to utilise Cutaneous Respiration has enabled the evolution of the largest assemblage of subterranean dytiscids in the world.
Carsten Werner - One of the best experts on this subject based on the ideXlab platform.
-
Wetting Resistance at Its Topographical Limit: The Benefit of Mushroom and Serif T Structures
2016Co-Authors: René Hensel, Ralf Helbig, Sebastian Aland, Hans-georg Braun, Axel Voigt, Christoph Neinhuis, Carsten WernerAbstract:Springtails (Collembola) are wingless arthropods adapted to Cutaneous Respiration in temporarily rain-flooded habitats. They immediately form a plastron, protecting them against suffocation upon immersion into water and even low-surface-tension liquids such as alkanes. Recent experimental studies revealed a high-pressure resistance of such plastrons against collapse. In this work, skin sections of Orthonychiurus stachianus are studied by transmission electron microscopy. The micrographs reveal cavity side-wall profiles with characteristic overhangs. These were fitted by polynomials to allow access for analytical and numerical calculations of the breakthrough pressure, that is, the barrier against plastron collapse. Furthermore, model profiles with well-defined geometries were used to set the obtained results into context and to develop a general design principle for the most robust surface structures. Our results indicate the decisive role of the sectional profile of overhanging structures to form a robust heterogeneous wetting state for low-surface-tension liquids that enables the omniphobicity. Furthermore, the design principles of mushroom and serif T structures pave the way for omniphobic surfaces with a high-pressure resistance irrespective of solid surface chemistry
-
Tunable nano-replication to explore the omniphobic characteristics of springtail skin
NPG Asia Materials, 2013Co-Authors: René Hensel, Ralf Helbig, Sebastian Aland, Axel Voigt, Christoph Neinhuis, Carsten WernerAbstract:Springtails (Collembola) are wingless arthropods adapted to Cutaneous Respiration in temporarily rain-flooded and microbially contaminated habitats by a non-wetting and antiadhesive skin surface that is mechanically rather stable. Recapitulating the robust and effectively repellent surface characteristics of springtail skin in engineered materials may offer exciting opportunities for demanding applications, but it requires a detailed understanding of the underlying design principles. Towards this aim and based on our recent analysis of the structural features of springtail skin, we developed a tunable polymer replication process to dissect the contributions of different structural elements and surface chemistry to the omniphobic performance of the cuticle. The Cassie–Wenzel transition at elevated pressures was explored by in situ plastron collapse experiments and by numerical FEM simulations. The results obtained unravel the decisive role of nanoscopic cuticle structures for the protection of springtails against wetting, and explain how the evolved nanotopography enables the production of omniphobic surfaces even from intrinsically hydrophilic polymer materials. Springtails, wingless arthropods, are adapted to Cutaneous Respiration in temporarily rain-flooded habitats by a hierarchically structured skin surface. A tunable polymer replication process was applied to dissect the contributions of different structural elements and surface chemistry to the omniphobic performance of the skin. The wetting behavior of a material's surface is a property of fundamental interest to material scientists. Springtails, also known as collembola, are soil-dwelling arthropods that typically respire through their skin. To avoid suffocating in wet conditions, springtails have evolved a complex, hierarchically nanostructured skin surface that repels water with remarkable efficiency. Carsten Werner at the Leibniz Institute of Polymer Research Dresden, Germany, and his colleagues have carried out numerical simulations and made accurate polymer-based replicas of this skin surface in order to understand better its anti-wetting behavior. Their results show that tiny overhangs in the nanostructure help to trap air against the surface in the wet, providing an effective barrier against wetting. The researchers further showed that even intrinsically hydrophilic materials will repel water when structured in this way. An improved understanding of springtail skin behaviour provides valuable insights that will aid scientists to design engineered materials with improved anti-wetting properties.
-
Wetting Resistance at Its Topographical Limit: The Benefit of Mushroom and Serif T Structures
Langmuir : the ACS journal of surfaces and colloids, 2013Co-Authors: René Hensel, Ralf Helbig, Sebastian Aland, Hans-georg Braun, Axel Voigt, Christoph Neinhuis, Carsten WernerAbstract:Springtails (Collembola) are wingless arthropods adapted to Cutaneous Respiration in temporarily rain-flooded habitats. They immediately form a plastron, protecting them against suffocation upon immersion into water and even low-surface-tension liquids such as alkanes. Recent experimental studies revealed a high-pressure resistance of such plastrons against collapse. In this work, skin sections of Orthonychiurus stachianus are studied by transmission electron microscopy. The micrographs reveal cavity side-wall profiles with characteristic overhangs. These were fitted by polynomials to allow access for analytical and numerical calculations of the breakthrough pressure, that is, the barrier against plastron collapse. Furthermore, model profiles with well-defined geometries were used to set the obtained results into context and to develop a general design principle for the most robust surface structures. Our results indicate the decisive role of the sectional profile of overhanging structures to form a robus...
