nils-herrmann/clean_scirepeval huggingface dataset:
Elastic instability model of rapid beak closure in hummingbirds.
Venue: Journal of Theoretical Biology

The hummingbird beak, specialized for feeding on floral nectars, is also uniquely adapted to eating flying insects. During insect capture the beak often appears to close at a rate that cannot be explained by direct muscular action alone. Here we show that the lower jaw of hummingbirds has a shape and compliance that allows for a controlled elastic snap. Furthermore, hummingbirds have the musculature needed to independently bend and twist the sides of the lower jaw. According to both our simple physical model and our elastic instability calculation, the jaw can be smoothly opened and then snapped closed through an appropriate sequence of bending and twisting actions by the muscles of the lower jaw.
Evidence for a vertebrate catapult: elastic energy storage in the plantaris tendon during frog jumping
Venue: Biology Letters

Anuran jumping is one of the most powerful accelerations in vertebrate locomotion. Several species are hypothesized to use a catapult-like mechanism to store and rapidly release elastic energy, producing power outputs far beyond the capability of muscle. Most evidence for this mechanism comes from measurements of whole-body power output; the decoupling of joint motion and muscle shortening expected in a catapult-like mechanism has not been demonstrated. We used high-speed marker-based biplanar X-ray cinefluoroscopy to quantify plantaris muscle fascicle strain and ankle joint motion in frogs in order to test for two hallmarks of a catapult mechanism: (i) shortening of fascicles prior to joint movement (during tendon stretch), and (ii) rapid joint movement during the jump without rapid muscle-shortening (during tendon recoil). During all jumps, muscle fascicles shortened by an average of 7.8 per cent (54% of total strain) prior to joint movement, stretching the tendon. The subsequent period of initial joint movement and high joint angular acceleration occurred with minimal muscle fascicle length change, consistent with the recoil of the elastic tendon. These data support the plantaris longus tendon as a site of elastic energy storage during frog jumping, and demonstrate that catapult mechanisms may be employed even in sub-maximal jumps.
Chemical Identity of a Rotting Animal-Like Odor Emitted from the Inflorescence of the Titan Arum (Amorphophallus titanum)
Venue: Bioscience, Biotechnology, and Biochemistry

The titan arum, Amorphophallus titanum, is a flowering plant with the largest inflorescence in the world. The flower emits a unique rotting animal-like odor that attracts insects for pollination. To determine the chemical identity of this characteristic odor, we performed gas chromatography-mass spectrometry-olfactometry analysis of volatiles derived from the inflorescence. The main odorant causing the smell during the flower-opening phase was identified as dimethyl trisulfide, a compound with a sulfury odor that has been found to be emitted from some vegetables, microorganisms, and cancerous wounds.
Resilience in social insect infrastructure systems
Venue: Journal of the Royal Society Interface

Both human and insect societies depend on complex and highly coordinated infrastructure systems, such as communication networks, supply chains and transportation networks. Like human-designed infrastructure systems, those of social insects are regularly subject to disruptions such as natural disasters, blockages or breaks in the transportation network, fluctuations in supply and/or demand, outbreaks of disease and loss of individuals. Unlike human-designed systems, there is no deliberate planning or centralized control system; rather, individual insects make simple decisions based on local information. How do these highly decentralized, leaderless systems deal with disruption? What factors make a social insect system resilient, and which factors lead to its collapse? In this review, we bring together literature on resilience in three key social insect infrastructure systems: transportation networks, supply chains and communication networks. We describe how systems differentially invest in three pathways to resilience: resistance, redirection or reconstruction. We suggest that investment in particular resistance pathways is related to the severity and frequency of disturbance. In the final section, we lay out a prospectus for future research. Human infrastructure networks are rapidly becoming decentralized and interconnected; indeed, more like social insect infrastructures. Human infrastructure management might therefore learn from social insect researchers, who can in turn make use of the mature analytical and simulation tools developed for the study of human infrastructure resilience.
Experimental Studies and Dynamics Modeling Analysis of the Swimming and Diving of Whirligig Beetles (Coleoptera: Gyrinidae)
Venue: PLOS Computational Biology

Whirligig beetles (Coleoptera, Gyrinidae) can fly through the air, swiftly swim on the surface of water, and quickly dive across the air-water interface. The propulsive efficiency of the species is believed to be one of the highest measured for a thrust generating apparatus within the animal kingdom. The goals of this research were to understand the distinctive biological mechanisms that allow the beetles to swim and dive, while searching for potential bio-inspired robotics applications. Through static and dynamic measurements obtained using a combination of microscopy and high-speed imaging, parameters associated with the morphology and beating kinematics of the whirligig beetle's legs in swimming and diving were obtained. Using data obtained from these experiments, dynamics models of both swimming and diving were developed. Through analysis of simulations conducted using these models it was possible to determine several key principles associated with the swimming and diving processes. First, we determined that curved swimming trajectories were more energy efficient than linear trajectories, which explains why they are more often observed in nature. Second, we concluded that the hind legs were able to propel the beetle farther than the middle legs, and also that the hind legs were able to generate a larger angular velocity than the middle legs. However, analysis of circular swimming trajectories showed that the middle legs were important in maintaining stable trajectories, and thus were necessary for steering. Finally, we discovered that in order for the beetle to transition from swimming to diving, the legs must change the plane in which they beat, which provides the force required to alter the tilt angle of the body necessary to break the surface tension of water. We have further examined how the principles learned from this study may be applied to the design of bio-inspired swimming/diving robots.
Design and mechanical properties of insect cuticle.
Venue: Arthropod Structure & Development

Since nearly all adult insects fly, the cuticle has to provide a very efficient and lightweight skeleton. Information is available about the mechanical properties of cuticle-Young's modulus of resilin is about 1 MPa, of soft cuticles about 1 kPa to 50 MPa, of sclerotised cuticles 1-20 GPa; Vicker's Hardness of sclerotised cuticle ranges between 25 and 80 kgf mm(-2); density is 1-1.3 kg m(-3)-and one of its components, chitin nanofibres, the Young's modulus of which is more than 150 GPa. Experiments based on fracture mechanics have not been performed although the layered structure probably provides some toughening. The structural performance of wings and legs has been measured, but our understanding of the importance of buckling is lacking: it can stiffen the structure (by elastic postbuckling in wings, for example) or be a failure mode. We know nothing of fatigue properties (yet, for instance, the insect wing must undergo millions of cycles, flexing or buckling on each cycle). The remarkable mechanical performance and efficiency of cuticle can be analysed and compared with those of other materials using material property charts and material indices. Presented in this paper are four: Young's modulus-density (stiffness per unit weight), specific Young's modulus-specific strength (elastic hinges, elastic energy storage per unit weight), toughness-Young's modulus (fracture resistance under various loading conditions), and hardness (wear resistance). In conjunction with a structural analysis of cuticle these charts help to understand the relevance of microstructure (fibre orientation effects in tendons, joints and sense organs, for example) and shape (including surface structure) of this fibrous composite for a given function. With modern techniques for analysis of structure and material, and emphasis on nanocomposites and self-assembly, insect cuticle should be the archetype for composites at all levels of scale.
Male Eufriesia purpurata, a DDT-collecting euglossine bee in Brazil
Venue: Nature

While studying the ecology of the malaria vector Anopheles (Nyssorhynchus) darlingi Root along the Ituxi River, Amazonas, Brazil, we observed aggregates of bees on the walls of houses that were routinely sprayed with DDT. Several bees collected from DDT-treated house walls in August 1978 were identified as male specimens of Eufriesia purpurata (Moscary) of the tribe Euglossini (Hymenoptera: Apoidae). (The bees were identified as Euplusia purpurata by Anthony Raw, Laboratorio de Ecologia, Universidade de Brasilia. The change of generic name from Euplusia to Eufriesia is based on ref. 1.) These bees were well known to the local residents as the insects that eat DDT and we present here the first documentation that they (1) are attracted to DDT, (2) actively collect large quantities of DDT from treated house walls and (3) suffer no apparent insecticidal effects. We also found that the frequency of house visiting is most intense during July to September. Most bees arrive at houses before 12.00 h, remain 2–3 h and return on subsequent days to collect more DDT. Noise produced by bees as they collected DDT was a notable disturbance to 76% of 21 families interviewed along the Ituxi River.
Brain Cooling: An Economy Mode of Temperature Regulation in Artiodactyls.
Venue: Physiology

Artiodactyls employ selective brain cooling (SBC) regularly during experimental hyperthermia. In free-ranging antelopes, however, SBC often was present when body temperature was low but absent when brain temperature was near 42 degrees C. The primary effect of SBC is to adjust the activity of the heat loss mechanisms to the magnitude of the heat stress rather than to the protection of the brain from thermal damage.
Desert locust gregarization: a conceptual kinetic model
Venue: Journal of Orthoptera Research

A better understanding of the mechanisms that underlie phase transformation in a solitarious desert locust population is an important prerequisite for the development of a quantitative gregarization model and for predicting locust outbreaks. Two types of processes are involved: 1) clustering at diminishing spatial scales, which brings dispersed locusts together and which, in patchy micro-environments with a concentrated food resource, gives rise to nuclei of pheromone-emitting, gregarizing insects; and 2) recruitment processes which promote the horizontal spread of gregarious traits from such nuclei. Because of the heterogeneity of typical breeding habitats and divergent behavior of the 2 phases of the insect, there is a dynamic interplay between the forces of crowd formation and those of dispersal. All the key steps in the course of phase change are reversible and for successful development of a viable gregarious population, all must proceed at optimal pace toward the gregarious phase. The process resembles a chemical transformation that involves a series of reversible sequential steps and may, likewise, be treated as a series of equilibria. Such a conceptual model may constitute a useful framework for quantitative studies in desert locust primary breeding areas and in the development of a predictive gregarization model.
Nanoscale biomimetics studies of Salvinia molesta for micropattern fabrication.
Venue: Joint International Conference on Information Sciences

The emerging field of biomimetics allows one to take inspiration from nature and mimic it in order to create various products, devices and structures. There are a large number of objects, including bacteria, plants, land and aquatic animals and seashells, with properties of commercial interest. The subject of interest for this research is the water fern Salvinia molesta because of its ability to trap air. Air-retaining surfaces are of technological interest due to their ability to reduce drag when used for fluid transport, ship coatings and other submersible industrial products in which drag is a concern. The purpose of this research is to mimic the air trapping ability of S. molesta in order to prove that a structure can be created in the lab that can mimic the behavior of the fern as well as demonstrate microfabrication techniques that can be utilized in industry to produce such materials. In this work, a novel methodology for the fabrication of microstructures that mimic the water-pinning and air-trapping ability of S. molesta is introduced. Water contact angle, water roll angle and adhesive force of the new microstructure and water fern are investigated.
Biology Reveals New Ways to Hold on Tight
Venue: Science

At an unusual recent meeting, biologists and materials scientists swapped notes about how natural and artificial adhesives work. The materials scientists discussed physical or chemical properties that biologists should consider as they try to figure out how nature performs its sticky tricks. The biologists described how various organisms stay put. By bringing the two disciplines together, the Defense Advanced Research Projects Agency, which funded the symposium, hoped to stimulate insights that might one day lead to more effective adhesives.
Regulation of brain temperature in winter-acclimatized reindeer under heat stress
Venue: The Journal of Experimental Biology

Reindeer (Rangifer tarandus) are protected against the Arctic winter cold by thick fur of prime insulating capacity and hence have few avenues of heat loss during work. We have investigated how these animals regulate brain temperature under heavy heat loads. Animals were instrumented for measurements of blood flow, tissue temperatures and respiratory frequency (f) under full anaesthesia, whereas measurements were also made in fully conscious animals while in a climatic chamber or running on a treadmill. At rest, brain temperature (Tbrain) rose from 38.5±0.1°C at 10°C to 39.5±0.2°C at 50°C, while f increased from ×7 to ×250 breaths min–1, with a change to open-mouth panting (OMP) at Tbrain 39.0±0.1°C, and carotid and sublingual arterial flows increased by 160% and 500%, respectively. OMP caused jugular venous and carotid arterial temperatures to drop, presumably owing to a much increased respiratory evaporative heat loss. Angular oculi vein (AOV) flow was negligible until Tbrain reached 38.9±0.1°C, but it increased to 0.81 ml min–1 kg–1 at Tbrain 39.2±0.2°C. Bilateral occlusion of both AOVs induced OMP and a rise in Tbrain and f at Tbrain >38.8°C. We propose that reindeer regulate body and, particularly, brain temperature under heavy heat loads by a combination of panting, at first through the nose, but later, when the heat load and the minute volume requirements increase due to exercise, primarily through the mouth and that they eventually resort to selective brain cooling.
Lymphatic collecting vessel maturation and valve morphogenesis.
Venue: Microvascular Research

The lymphatic vasculature plays an essential role in the maintenance of tissue interstitial fluid balance and in the immune response. After capture of fluids, proteins and antigens by lymphatic capillaries, lymphatic collecting vessels ensure lymph transport. An important component to avoid lymph backflow and to allow a unidirectional flow is the presence of intraluminal valves. Defects in the function of collecting vessels lead to lymphedema. Several important factors and signaling pathways involved in lymphatic collecting vessel maturation and valve morphogenesis have now been discovered. The present review summarizes the current knowledge about the key steps of lymphatic collecting vessel development and maturation and focuses on the regulatory mechanisms involved in lymphatic valve formation.
Osmotic adjustment and plant adaptation to environmental changes related to drought and salinity.
Venue: Environmental Reviews

The salinization and water deficit of soil are widespread environmental problems in limiting plant survival, growth, and productivity. However, some plants could adopt some strategies to resist salinity and drought stresses. Among these strategies, the mechanism of osmotic adjustment could help plants and algae to avoid ion toxicity and maintain water uptake in both stresses by accumulating large quantities of osmolytes. Two types of osmolytes, organic solutes and inorganic ions, play a key role in osmotic adjustment. Different osmolytes and their osmotic adjustment actions are different according to their distribution in different plants. Organic solutes, known as compatible solutes, include amino acids, glycerol, sugars, and other low molecular weight metabolites, serve a function in cells to lower or balance the osmotic potential of intracellular and extracellular ions in resistance to osmotic stresses. Inorganic ions for osmotic adjustment are mainly Na+, K+, Ca2+, and Cl–. Inorganic ions make great c...
Electron transfer in syntrophic communities of anaerobic bacteria and archaea
Venue: Nature Reviews Microbiology

Interspecies electron transfer is a key process in methanogenic and sulphate-reducing environments. Bacteria and archaea that live in syntrophic communities take advantage of the metabolic abilities of their syntrophic partner to overcome energy barriers and break down compounds that they cannot digest by themselves. Here, we review the transfer of hydrogen and formate between bacteria and archaea that helps to sustain growth in syntrophic methanogenic communities. We also describe the process of reverse electron transfer, which is a key requirement in obligately syntrophic interactions. Anaerobic methane oxidation coupled to sulphate reduction is also carried out by syntrophic communities of bacteria and archaea but, as we discuss, the exact mechanism of this syntrophic interaction is not yet understood.
An insect trap as habitat: cohesion-failure mechanism prevents adhesion of Pameridea roridulae bugs to the sticky surface of the plant Roridula gorgonias
Venue: The Journal of Experimental Biology

The glandular trichomes of the plant Roridula gorgonias release an extremely adhesive, visco-elastic, resinous secretion that traps a variety of insects, including those having a considerable body size. However, the specialized mutualistic mirid bug Pameridea roridulae lives and walks on this sticky plant surface without being trapped. We have sought to reveal the mechanism underlying the apparent non-sticky nature of the cuticle of this bug. In this study, we have visualized intact plant and insect surfaces using cryo-scanning electron microscopy and measured the adhesive properties of the plant secretion on different surfaces. We present a combination of structural and experimental results that suggest that a thick and cohesively weak film of an outermost, epicuticular greasy secretion acts as a `sloughing-off' layer, preventing the formation of contacts between the sticky plant secretion and the solid insect cuticle. In a comparative study of fresh cuticle fractures of flies representing a typical prey of R. gorgonias, a thin, fragmentary layer of epicuticular grease was revealed. These results indicate that, when trapping prey, the plant adhesive might form proper contact with solid islands of the insect cuticle that are free of epicuticular grease.
Taste perception in honeybees: just a taste of honey?
Venue: Arthropod-plant Interactions

The advent of the genomic era has opened new doors to understand the fundamental organization of living organisms and has therefore promoted a fertile field of comparative research that intends to identify similarities and differences between related and unrelated species at the genomic level. One of the organisms whose genome has been recently decoded is that of the honeybee Apis mellifera, enabling a direct comparison with another well-studied insect, the fruit fly Drosophila melanogaster. It was reported that the honeybee has only ten gustatory receptors and thus a very poor taste perception compared to Drosophila, which presents 68 gustatory receptors, and the mosquito Anopheles gambiae, which presents 76 gustatory receptors. In this forum article, we discuss the implications of these findings taking into account previous and new discoveries on honeybee gustation based on behavioral and neurobiological studies by several authors and us. We conclude that the world of taste of a honeybee might not be as poor as proposed and that further studies should integrate molecular, neurobiological, behavioral and ecological approaches to better characterize taste perception in bees.
The Functional Morphology of Starfish Tube Feet: The Role of a Crossed-Fiber Helical Array in Movement.
Venue: The Biological Bulletin

The morphology and mechanics of the tube feet, ampullae, and lateral and radial canals of the water vascular systems of Luidia clathrata and Astropecten articulatus (Echinodermata, Asteroidea) were analyzed. Histological methods, based on embedding in both paraffin and glycol methacrylate, were used to document the arrangement of muscle and connective tissue. The tube foot wall includes longitudinal muscles and connective tissue fibers, the latter arranged in a crossed-fiber helical array, with a fiber angle of about 67{deg} in elongated tube feet. No evidence was found for the circular rings of connective tissue reported in earlier studies; the appearance of rings is probably an artifact of folding. The ampullae are bilobed and include circumferentially arranged muscle fibers and connective tissue fibers aligned 90{deg} to the muscle. The lateral canals are short and equipped with oneway flap valves similar to those described for other echinoderms. The radial canal is thin-walled, nonmuscular, and enclosed in the connective tissue and ossicles of the ambulacrum. Frame-by-frame video analysis of both intact animals and animals with "windows" cut in the arm wall was used to document the movements of the tube feet and ampullae. No evidence was found for the previously suggested role of the radial canal in protracting the tube feet. The ampullae protract the tube feet and antagonize the tube foot musculature. The fiber angle of the connective tissue allows protraction and prevents dilation of the tube feet, and limits elongation of the ampullae.
How ticks get under your skin: insertion mechanics of the feeding apparatus of Ixodes ricinus ticks
Venue: Proceedings of The Royal Society B: Biological Sciences

The tick Ixodes ricinus uses its mouthparts to penetrate the skin of its host and to remain attached for about a week, during which time Lyme disease spirochaetes may pass from the tick to the host. To understand how the tick achieves both tasks, penetration and attachment, with the same set of implements, we recorded the insertion events by cinematography, interpreted the mouthparts’ function by scanning electron microscopy and identified their points of articulation by confocal microscopy. Our structural dynamic observations suggest that the process of insertion and attachment occurs via a ratchet-like mechanism with two distinct stages. Initially, the two telescoping chelicerae pierce the skin and, by moving alternately, generate a toehold. Subsequently, a breaststroke-like motion, effected by simultaneous flexure and retraction of both chelicerae, pulls in the barbed hypostome. This combination of a flexible, dynamic mechanical ratchet and a static holdfast thus allows the tick to solve the problem of how to penetrate skin and also remain stuck for long periods of time.