Food Capture Research Articles

Beyond head and wings: Unveiling influence of diet, body size, and phylogeny on the evolution of the femur in phyllostomid bats.

Phyllostomidae, the most diverse family of Neotropical bats, encompass 230 species with varied dietary habits and food acquisition methods. Their feeding niche diversification has shaped skull and wing morphologies through natural selection, reflecting food processing and flight strategies. Yet, evolution of bat hindlimbs, especially in phyllostomids, remains little understood. Previous studies highlighted the femur's morphology as a key to understanding the evolution of quadrupedalism in yangochiropteran bats, including the adept walking observed in vampire bats (Desmodontinae). Here, we aimed to describe the femoral morphological variation in Phyllostomidae, correlating this with body size and assessing the effects of phylogenetic history, dietary habits, and hindlimb usage. Analyzing 15 femoral traits from 45 species across 9 subfamilies through phylogenetically informed methods, we discovered a significant phylogenetic structure in femoral morphology. Allometric analysis indicated that body mass accounts for about 85% of the variance in phyllostomid femoral size and about 11% in femoral shape. Relatively smaller femurs showed to be typical in Stenodermatinae, Lonchophyllinae, and Glossophaginae, in contrast to the larger femurs of Phyllostominae, Desmodontinae, Micronycterinae, and Lonchorrhininae. Furthermore, extensive femur shape variation was detected, with the most distinct morphologies in vampire bats, followed by frugivorous species. Adaptive evolutionary models related to diet more effectively explained variations in femoral relative size and shape than stochastic models. Contrary to the conventional belief of limited functional demand on bat femurs, our findings suggest that femoral morphology is significantly influenced by functional demands associated with diet and food capture, in addition to being partially structured by body size and shared evolutionary history.

The morphology of the branchial skeleton of heterocongrines (Anguilliformes: Congridae) and its relation to their diet

Members of the subfamily Heterocongrinae (Congridae) are a peculiar group of anguilliform eels that construct sandy borrows, form large colonies, and are popularly recognized as garden eels. They live with most of their bodies inside self-constructed borrows exposing their heads and trunk to feed on zooplankton, preferably copepods, that are brought passively by currents. As plankton feeders there was a suspicion that their branchial skeleton would have structures that could aid in the filtering process, such as highly developed or modified branchial rakers, which are observed in other suspension-feeding fishes, such as anchovies and sardines. Branchial rakers, however, were considered to be absent across Anguilliformes (except for Protanguilla). Nonetheless, specimens that were examined using clearing and staining and computed tomography showed, in all cases, branchial rakers associated with their gill arches. Heterocongrines have branchial rakers across their first to fourth branchial arches. These rakers are conical and apparently unossified, but further studies are necessary to attest its degree of ossification or its complete absence. Their pharyngeal tooth plates are reduced, a condition that may reflect their preference for smaller food items. Additionally, they may use crossflow filtering to feed, although detailed studies are necessary to clarify if hydrosol sieving may also aid in food capture. Furthermore, the present study proposes that the presence of branchial rakers should be better investigated in Anguilliformes with similar feeding habits as heterocongrines, considering that these structures may be more widespread within the group than previously considered.

A crinoid fauna and a new species of Pycnocrinus from the Martinsburg Formation (Upper Ordovician), lower Hudson Valley, New York

Abstract A new crinoid fauna has been discovered in the Upper Ordovician (Katian) Martinsburg Formation at a small shale quarry, locally known as the ‘Shale Bank,’ on the Shawangunk Ridge in Ulster County, NY. The assemblage, which is from a relatively low energy, offshore mud-bottom environment, includes four identified species, including a new species of glyptocrinid camerate, Pycnocrinus mohonkensis n. sp., described herein. Crinoid taxa in order of increasing branch density in the assemblage include (1) the dicyclic inadunate Merocrinus curtus with irregularly isotomous and heterotomous, non-pinnulate arms and a stout cylindrical column exceeding 700 mm; (2) the disparids Cincinnaticrinus varibrachialus, with heterotomous non pinnulate arms, and Ectenocrinus simplex, with extensively branched ramulate arms and meric columns of 460–500 mm; and (3) the camerate Pycnocrinus mohonkensis n. sp., with uniserial pinnulate arms and a somewhat shorter column. Some cylindrical stems with nodose and holomeric columnals are thought to belong to unknown camerate crinoids with pinnulate arms. Filtration theory is used to model food capture in the Martinsburg crinoids. Surprisingly, even densely pinnulate camerates were able to survive in this setting, suggesting that ambient currents attained velocities exceeding 25 cm/sec even in this offshore setting. Similar assemblages were widespread in eastern Laurentia during the Late Ordovician. UUID: http://zoobank.org/23ca31e8-f572-4520-ba1d-891e3abb950d

The effect of tessellation on stiffness in the hyoid arch of elasmobranchs.

Tessellated cartilage forms much of the skeleton of sharks and rays, in contrast to most other aquatic vertebrates who possess a skeleton of bone. Interestingly, many species of sharks and rays also regularly generate exceptionally high forces in the execution of day-to-day activities, such as when feeding on bony fish, mammals, and hard-shelled invertebrates. Tessellated cartilage differs from other types of cartilage in that they are covered by an outer layer of small mineralized tiles (tesserae) that are connected by fibrous connective tissue. Tesserae, therefore, are hypothesized to play a role in stiffening the cartilaginous skeleton for food capture and other activities that require the generation of high forces. In this study, the hyomandibula and ceratohyal cartilages, which support the jaw and throat regions of sharks and rays, were tested under compressive load in a material testing system to determine the contribution of tesserae to stiffness. Previous hypotheses suggest an abrupt upward shift in the slope of the stress-strain curve in tessellated materials due to collision of tesserae. Young's Modulus (E) was calculated and used to evaluate cartilage stiffness in a range of elasmobranch species. Our results revealed that there was an abrupt shift in Young's Modulus for elements loaded in compression. We postulate that this shift, characterized by an inflection point in the stress-strain curve, is the result of the tesserae approaching one another and compressing the intervening fibrous tissue, supporting the hypothesis that tesserae function to stiffen these cartilages under compressive loading regimes. Using published data for nontessellated cartilage for comparison, we show that this shift is, as expected, unique to tessellated cartilage.

Repertoire of food acquisition behaviors in Western Palearctic shorebirds (Aves, Charadriiformes)

Shorebirds are iconic examples of food resource partitioning through use of contrasted morphological structures to acquire food. Differences in beak lengths and shapes allow species catching their food at various sediment depths. Contrasted leg lengths allow species foraging at distinct water depths. Despite these morphological differences, shorebirds use a small number of stereotyped behaviors for food acquisition. We classify these behaviors by analyzing video sequences of ca. two dozen species of Western Palearctic shorebirds, during migration or wintering. We suggest disassembling food acquisition in three successive stages: foraging, feeding, and swallowing. The foraging stage regroups the locomotion behaviors associated to food detection, and the behaviors used during food capture. The feeding stage encompasses the handling behaviors used to kill or stun the prey and to extract its edible parts, and the behaviors used to transport the prey from the distal part of the beak to the bird’s pharynx. In the swallowing stage, the edible parts of the prey enter the pharynx. We show that three of these behaviors (locomotion, capture and transport) are made up of stereotypical, mutually exclusive components, and can be considered as performances. Each of our study species use one or maximum two components of these three performances. Overall, our study provides insights on interspecific variation in shorebird food acquisition behaviors that we put in a phylogenetic perspective. We confirm the long-standing hypothesis that pecking is the plesiomorphic behavior of food capture, and we show that those locomotion and transport behaviors associated with pecking differ from those associated with derived capture behaviors, leading to a syndrome of food acquisition behaviors in shorebirds.

Food capture and escape behavior of Leposternon microcephalum Wagler, 1824 (Squamata: Amphisbaenia).

Amphisbaenians are fossorial reptiles that have a cylindrical and elongated body covered with scales arranged in rings, and are all apodal, except for the three species of the genus Bipes. The amphisbaenian diet consists of a variety of invertebrates and small vertebrates. As these animals live underground, many aspects of their natural history are difficult to study. Most feeding studies of amphisbaenians have focused on the composition of the diet and feeding ecology, and the data available on feeding behavior are based on precursory observations. The present study describes the food capture behavior of Leposternon microcephalum Wagler, 1824 in captivity. In this experiment we used non-live bait (moist cat food), which was placed near a burrow opening, on the surface of the substrate. Three animals were monitored visually and filmed using cellphone cameras deployed at fixed points, to capture images from the dorsal and lateral perspectives of the study subjects. Two principal types of behavior were observed: the capture of food and defense mechanisms. The strategies used to capture the food were similar to those observed in other fossorial species. Although the backward movement has already been observed and described, we were able to record this movement being used as an escape strategy. These findings enrich our knowledge on different aspects of the natural history of the amphisbaenians.

3D-printed micrometer-scale wireless magnetic cilia with metachronal programmability.

Biological cilia play essential roles in self-propulsion, food capture, and cell transportation by performing coordinated metachronal motions. Experimental studies to emulate the biological cilia metachronal coordination are challenging at the micrometer length scale because of current limitations in fabrication methods and materials. We report on the creation of wirelessly actuated magnetic artificial cilia with biocompatibility and metachronal programmability at the micrometer length scale. Each cilium is fabricated by direct laser printing a silk fibroin hydrogel beam affixed to a hard magnetic FePt Janus microparticle. The 3D-printed cilia show stable actuation performance, high temperature resistance, and high mechanical endurance. Programmable metachronal coordination can be achieved by programming the orientation of the identically magnetized FePt Janus microparticles, which enables the generation of versatile microfluidic patterns. Our platform offers an unprecedented solution to create bioinspired microcilia for programmable microfluidic systems, biomedical engineering, and biocompatible implants.

Comparative analysis of cranial morphology in Middle-American heroine cichlids (Actinopterygii: Cichliformes).

Heroine cichlids are characterized by high morphological diversity, mainly in structures related to the capture and processing of food. The existence of ecomorphological groups has been proposed based on feeding behavior, where it is common for some phylogenetically unrelated species to show evolutionary convergence. Using geometric morphometrics and comparative phylogenetic methods, the variation in cranial morphology was evaluated for 17 species of heroine cichlids representing 5 ecomorphs. Cranial ecomorphs were recovered and significant differences were determined. Morphological variation of the ecomorphs was mainly explained by two axes: (1) the position of the mouth determined by the shape of the bones of the oral jaw and (2) the height of the head, defined by the size and position of the supraoccipital crest and the distance to the interopercle-subopercle junction. Cranial variation among species was related to phylogeny. To better understand the evolution of cranial morphology, it is necessary to evaluate the morphofunctional relationship of other anatomical structures related to feeding, as well as to increase the number of study species in each ecomorph by including other lineages.

Oropharyngeal morphological aspects of Arapaima gigas (Schinz, 1822)

The study of the functional anatomy of the digestive system of fish, in particular the oropharyngeal cavity, is of great importance because it allows inferences about the feeding habit, mechanisms of capture, selection, and processing of food carried out by different species. Thus, the aim of this study was to describe the anatomical adaptations of the oropharyngeal cavity of the pirarucu (Arapaima gigas Schinz, 1822) using scanning electron microscopy (SEM) techniques. The oropharyngeal cavity of six specimens of pirarucu was collected in juvenile phase, from Aquaculture Research Center at the Universidade Federal de Rondônia (UNIR), created for commercial purposes. The anatomical pieces were fixed in 10% buffered formalin and processed for SEM analysis. Anatomically, the oropharyngeal cavity of the pirarucu is composed of five pairs of branchial arches, apical portion of the tongue, floor of the tongue, lower pharyngeal area, and upper pharyngeal plate. In SEM, we observed that the mucosa of the apex of the tongue and the upper pharyngeal roof have a smooth texture and are covered by squamous cells with numerous small openings scattered over the surface. The portions of the floor of the tongue and the lower pharyngeal area, on the other hand, have adaptations in the form of a projectile and numerous sensory papillae, giving a rough texture to the region. Thus, the oropharyngeal cavity of pirarucu is adapted for the capture, apprehension, and swallowing of its prey, with signs of carnivory.

Effects of Salinity and Dissolved Oxygen Concentration on the Tail-Flip Speed and Physiologic Response of Whiteleg Shrimp, Litopenaeus vannamei

The swimming ability of shrimp is important for their survival and growth, which directly affects their avoidance of enemies and uncomfortable environment, search and capture of food, reproductive behavior, and distribution. The knowledge concerning the swimming ability of shrimp can be widely used in the conservation of fishery resources, improving capture efficiency and stock enhancement. As one of the edible marine organisms, Litopenaeus vannamei is a traditional fishery resource and an important economic aquaculture species in China. Dissolved oxygen (DO) concentration and salinity are considered to play crucial roles in the swimming ability of L. vannamei. The tail-flip speed (Stf) of whiteleg shrimp L. vannamei (79.90 ± 0.41 mm, 5.76 ± 0.10 g) that were exposed to various salinities (20‰, 25‰, 30‰, 35‰, and 40‰) and DO concentrations (1.9, 3.8, 6.8, and 13.6 mg/L) was determined under laboratory conditions. Metabolite concentrations in the hemolymph, hepatopancreas, and abdominal muscles were measured before and after tail-flip fatigue to evaluate the physiologic effects of fatigue in L. vannamei. The results showed that salinity and DO significantly affected the Stf of L. vannamei. The Stf increased and subsequently decreased with the increase in salinity from 20‰ to 40‰. The relationship between Stf and salinity (s, ‰) can be expressed by the quadratic model as Stf = −0.2386s2 + 15.528s − 145.12, R2 = 0.9693. The optimum salinity and corresponding maximum Stf were 32.54‰ and 107.52 cm/s, respectively. The Stf increased as the DO concentration increased from 1.9 mg/L to 13.6 mg/L. The relationship between Stf and DO (mg/L) can be expressed by the power model as Stf = 75.621 DO0.1753, R2 = 0.9981. The different salinities and DO concentrations directly affected the physiology of the shrimp, inducing changes in hepatopancreas total protein, plasma total protein, abdominal muscle lactate, plasma lactate, plasma glucose, hepatopancreas glycogen, and abdominal muscle glycogen concentration. Fatigue from tail-flip led to severe loss of hepatopancreas glycogen under 20‰ salinity and plasma glucose under 25‰, 30‰, and 35‰ salinity. The triglyceride and lactate in the plasma concentration increased significantly in a range of salinities. In the DO concentration experiment, fatigue from tail-flip led to a severe loss of plasma glucose under 1.9 mg/L and 3.8 mg/L DO concentrations. The plasma lactate concentration increased significantly in all DO groups. The results suggested that the inappropriate salinity and DO significantly limited the tail-flip speed of shrimp, which was due to the accumulation of metabolites. The proper salinity and DO accelerated the elimination of metabolites, reduced the energy consumption of shrimp, and thus, improved the exercise ability of shrimp. This conclusion is of particular value in evaluating the swimming ability of shrimp and understanding its ecological processes to improve capture and rearing techniques.

Screening and identification of miRNAs regulating Tbx4/5 genes of Pampus argenteus.

BackgroundSilver pomfret (Pampus argenteus) is one of the most widely distributed and economically important pelagic fish species. However, an unique morphological feature of P. argenteus is the loss of pelvic fins, which can increase the energy requirement during food capture to some extent and is therefore not conducive to artificial culture. Tbx4/5 genes are highly conserved regulatory factors that regulate limb development in vertebrates and are in turn regulated by microRNAs (miRNAs). However, the miRNAs that directly regulate the Tbx4/5 genes in P. argenteus remain to be elucidated.MethodsThe Tbx4/5 genes of P. argenteus were first cloned, and the small RNA transcriptomes were sequenced by high-throughput sequencing during the critical period of the fin development at days 1, 7, and 13 of hatching. The miRNAs regulating the Tbx4/5 genes of P. argenteus were subsequently predicted by bioinformatics analysis, and the related miRNAs were verified in vitro using a dual fluorescence reporter system.ResultsA total of 662 miRNAs were identified, of which 257 were known miRNAs and 405 were novel miRNAs were identified. Compared to day 1, 182 miRNAs were differentially expressed (DE) on day 7, of which 77 and 105 miRNAs were downregulated and upregulated, respectively, while 278 miRNAs were DE on day 13, of which 136 and 142 miRNAs were downregulated and upregulated, respectively. Compared to day 13, four miRNAs were DE on day 7, of which three miRNAs were downregulated and one miRNA was upregulated. The results of hierarchical clustering of the miRNAs revealed that the DE genes were inversely expressed between days 1 and 7, and between days 1 and 13 of larval development, indicating that the larvae were in the peak stage of differentiation. However, the number of DE genes between days 7 and 13 of larval development was relatively small, suggesting the initiation of development. The potential target genes of the DE miRNAs were subsequently predicted, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of target genes were performed. The results suggested that the DE miRNAs were involved in growth, development, and signal transduction pathways, of which the Wnt and Fgfs signaling pathways are known to play important roles in the growth and development of fins. The results of dual fluorescence reporter assays demonstrated that miR-102, miR-301c, and miR-589 had a significant negative regulatory effect on the 3′-UTR of the Tbx4 gene, while miR-187, miR-201, miR-219, and miR-460 had a significant negative regulatory effect on the 3′-UTR of the Tbx5 gene. Altogether, the findings indicated that miRNAs play an important role in regulating the growth and development of pelvic fins in P. argenteus. This study provides a reference for elucidating the interactions between the miRNAs and target genes of P. argenteus in future studies.

Functional morphology of cirri in the barnacle Amphibalanus improvisus (crustacea: Balanidae).

Barnacles rely heavily on their mobile cirri for food capture because of the sessile lifestyle. These filamentous food capturing devices are extended into the water current and perform undulating movements. Cuticular structures with corresponding musculature work together, to allow these highly repetitive movements. This paper studies the interplay between structure and function of the cirri using scanning electron microscopy (SEM), microcomputed tomography (µCT) and high-speed video recordings (HSV) in Amphibalanus improvisus. Barnacles use the external cuticle structures (denticles and setae) for efficient grooming, food capturing, and providing support for the muscular system responsible for movement control. Entanglement of the cirri during extension is probably avoided through an interlocking of the serrate setae on cirri IV-VI, creating a "zipper-like" effect, which was recorded here using the HSV. We analyzed the muscular arrangement using µCT and found a new flexor muscle in both the endo- and exopod of cirrus II. Supported by the intrinsic cirral muscles, the new flexor muscles may provide variable movements of the anterior cirri (cirri I-III), which is important for further food handling. Our results provide a foundation for further comparative studies of the feeding apparatus of barnacles and for possible implications in the area of bio-inspired robotics.

Dietary influences on head and neck ranges of motion in neotropical bats

AbstractThe primary functions of the tetrapod neck are to maintain head stability and facilitate head mobility. Both stability and mobility should be especially important during foraging. Head stability facilitates the function of the vestibulocochlear, auditory, and visual organs while mobility allows for the motion of that visual field as well as the mouth for food capture and processing. Species that rely on different resources should be under different selective pressures with regard to range of motion of the head and neck and the musculoskeletal morphologies that sustain them. Bats are useful model species to investigate these pressures because they display a wide variety of foraging behaviors. This study tests the hypothesis that dietary regime influences maximum ranges of motion found in the head and neck. To test this hypothesis, a dietarily diverse group of bats were caught in the field and their active ranges of head–neck motion were measured via photographs. Diet information was taken from the literature. Additionally, gross neck dimensions (mediolateral neck width and craniocaudal neck length) were measured using calipers. Phylogenetic statistical methods support the hypothesis and demonstrate that frugivorous species have much smaller ranges of head and neck motion. The results indicate that frugivorous species may require stiffness in their cervical spine in order to carry heavy fruits and maintain head stability simultaneously. Future work should investigate the anatomical differences in the head and neck among bats that influence this stiffness as well as other dietary behaviors that could be shaping the form and function of the head and neck.

Scope for Developmental Plasticity of Feeding Larvae of a Holothuroid, Contrasted with Other Echinoderm Larvae.

AbstractFeeding larvae of echinoderms appear to differ in scope for adaptive developmental plasticity in response to food. Extension of the ciliary band on narrow arms supported by skeletal rods, as in echinoid and ophiuroid larvae, may enable a greater increase in maximum clearance rate per cell added, conferring greater advantages from developing longer ciliary bands when food is scarce. Formation of the juvenile mouth and water vascular system at a new site, as in echinoid and asteroid larvae, permits extensive growth of the juvenile rudiment during larval feeding, with advantages from earlier or more growth of the rudiment when food is abundant. In contrast, plasticity in storage of nutrients is unrelated to the form of the ciliary band or the site of formation of the juvenile's mouth. Feeding larvae (auriculariae) of holothuroids lack arms supported by skeletal rods and formation of the mouth at a new site but as a unique feature store nutrients in hyaline spheres. In this study, more food for auriculariae of Apostichopus californicus resulted in juveniles (pentactulae) with longer and wider bodies and larger hyaline spheres, but effects of food supply on the size of most body parts of auriculariae were small. Auriculariae with more food developed relatively larger stomachs and larger posterior hyaline spheres, indications of greater nutrient storage. Auriculariae with less food developed relatively wider mouths and differed in some exterior dimensions, which might enhance the capture of food. Plasticity is limited in rudiment development and perhaps in structures for feeding, but plasticity in nutrient storage can provide advantageous compromises between duration of growth as a feeding larva and the condition of juveniles formed at metamorphosis.

Dietary shifts and niche partitioning throughout ontogeny reduce intraspecific competition in a pelagic generalist predator

Patterns of feeding strategy change throughout ontogeny according to size-specific abilities and requirements. Characterizing the extent and potential repeated occurrence of dietary differences within the population can improve understanding of the intraspecific predation regime and population dynamics. Here, we investigated size-related feeding habits and trophic niche partitioning of an iconic pelagic generalist predator, the jumbo squid Dosidicus gigas, by a combined analysis of morphologic indicators of feeding capability (fin and feeding apparatuses), trophic biochemical tracers (stable isotopes and fatty acids), and stomach contents. Results showed significant variation in prey composition, isotopic values, and fatty acid profiles with size. D. gigas exhibited a shift in diet at approximately 250 mm mantle length (ML). The trophic niche of small (ML ≤ 250 mm) and large (ML > 250 mm) squid revealed low potential for resource overlap, suggesting segregation in terms of spatial and food resources of different size groups. Large individuals tend to feed deeper and on smaller prey to optimize food capture costs and energy benefits. This feeding strategy is likely related to variability in the development of feeding capacity, increasing swimming ability, and metabolic demand as squid grow and may reduce intraspecific competition to improve survival. These results highlight the dietary flexibility of D. gigas and demonstrate that niche differentiation acts as a major factor in a cohort, which may have important implications for their population dynamics and management. In addition, this study demonstrates that using multiple diet tracers can highlight subtle differentiations in diet correlated to growth in a pelagic generalist predator.

Morphometric variation of Middle-American cichlids: Theraps– Paraneetroplus clade (Actinopterygii: Cichliformes: Cichlidae)

This study assesses the patterns of variation in body shape, and relations of morphological similarity among species of theTheraps–Paraneetroplusclade in order to determine whether body shape may be a trait in phylogenetic relations. A total of 208 specimens belonging to 10 species of theTheraps–Paraneetroplusclade were examined. The left side of each specimen was photographed; in each photograph, 27 fixed landmarks were placed to identify patterns in body shape variation. Images were processed by using geometric morphometrics, followed by a phylogenetic principal component analysis. The phylogenetic signal for body shape was then calculated. To determine the relations in morphological similarity, a dendrogram was created using the unweighted pair group method and arithmetic mean values, while a Procrustes ANOVA and post-hoc test were used to evaluate significant differences between species and habitats. We found three morphological groups that differed in body length and depth, head size, and the position of the mouth and eyes. The body shape analysis recovered the morphotypes of seven species, and statistical differences were demonstrated in eight species. Based on traits associated with cranial morphology,Wajpamheros nourissati(Allgayer, 1989) differed the most among the species examined. No phylogenetic signal was found for body shape; this trait shows independence from ancestral relatedness, indicating that there is little congruence between morphological and genetic interspecific patterns. As evidenced by the consistently convergent morphology of the species in theTheraps–Paraneetroplusclade, the diversification of the group is related to an ecological opportunity for habitat use and the exploitation of food resources. Although no phylogenetic signal was detected for body shape, there appears to be an order associated with cranial morphology-based phylogeny. However, it is important to evaluate the intraspecific morphologic plasticity produced by ecological segregation or partitioning of resources. Therefore, future morphological evolutionary studies should consider cranial structures related to the capture and processing of food.

Venomous Animals in the Portuguese Territory: Clinical Management of Bites and Stings

There are many native species of animals with the potential to cause severe disease in Portugal. Of the four clinically relevant snake species, the vipers (Vipera latastei and Vipera seoanei) are the most concerning. They can cause severe disease and require in-hospital management, monitoring and specific treatment, including the administration of anti-snake venom serum. The Malpolon monspessulanus and Macroprotodon brevis snakes cause mostly localized clinical manifestations, which do not require specific treatment. Only a minority of the spider species in Portugal possess chelicerae (mouthparts of the Chelicerata, shaped as either articulated fangs or pincers, which may contain venom or be connected to the venom glands and are used for predation or capture of food) long enough to perforate the human skin. Nevertheless, Latrodectus tredecimguttatus and Loxosceles rufescens spider bites may require specialized treatment in a hospital setting, as well as careful active symptom surveillance. Diversely, the treatment for Scolopendra cingulata and Scolopendra oraniensis centipedes' bites is merely symptomatic. The only existing scorpion species in Portugal is the Buthus ibericus; its sting typically causes local symptoms with intense pain, and its treatment consists essentially of analgesia. The insects of the Hymenoptera order, such as bees and wasps, have the ability to inject venom into the skin. Most people present only with local or regional inflammatory response, and symptomatic treatment is usually effective. Even so, individuals with hypersensitivity to bee venom may develop anaphylaxis. Several marine species in the Portuguese coast are venomous to humans, including weeverfish (Trachinidae family), stingrays (Dasyatis pastinaca, Taeniura grabata, Myliobatis aquila), red scorpion fish (Scorpaena scrofa), cnidaria (Pelagia noctiluca, Chrysaora hysoscella, Physalia physalis) and bearded fireworm (Hermodice carunculata); treatment is symptomatic. Contact with the larvae or bristles (chitinous structures with locomotor or tactile functions) of Thaumetopoea pityocampa (pine processionary) can cause cutaneous, ocular and, rarely, respiratory reactions; its management is also symptomatic.

Sophistication in a seemingly simple creature: a review of wild holothurian nutrition in marine ecosystems.

ABSTRACTHolothurians are marine invertebrates that are among the most widespread benthic megafauna communities by both biomass and abundance in shallow‐water and deep‐sea ecosystems, their functions supporting important ecological services worldwide. Despite their simple appearance as sea cucumbers, holothurians show a wide range of feeding practices. However, information on what and how these animals eat is scattered and potentially confusing. We provide a comprehensive review of holothurian nutrition in coastal and deep‐sea ecosystems. First, we describe morphological aspects of holothurian feeding and the ultrastructure of tentacles. We discuss the two processes for food capture, concluding that mucus adhesion is likely the main method; two mucous cells, type‐1 and type‐2, possibly allow the adhesion and de‐adhesion, respectively, of food particles. Secondly, this review aims to clarify behavioural aspects of holothurian suspension‐ and deposit‐feeding. We discuss the daily feeding cycle, and selective feeding strategies. We conclude that there is selectivity for fine and organically rich particles, and that feeding through the cloaca is also a route for nutrient absorption. Third, we provide a wide description of the diet of holothurians, which can be split into two categories: living and non‐living material. We suggest that Synallactida, Molpadida, Persiculida, Holothuriida and Elasipodida, ingest the same fractions, and emphasise the importance of bacteria in the diet of holothurians.

Effect of eutrophication on the functional diversity of zooplankton in shallow ponds in Northeast Brazil

Abstract Eutrophication is a process characterized by the enrichment of a given aquatic environment with nutrients, triggering a serious and growing ecological problem in continental aquatic ecosystems, including effects on the biodiversity and ecosystem functioning. For this, we predicted that eutrophication decreases zooplankton functional richness, evenness, divergence and dispersion, and changes the functional composition of zooplankton. Zooplankton and water features were sampled in sixteen shallow ponds in northeastern Brazil. Functional diversity aspects were calculated for each assembly (rotifers, cladocerans, and copepods) using multidimensional indexes and functional groups. Principal component analysis, multiple linear regression, hierarchical cluster analysis and distance-based redundancy analysis were performed to characterize the environmental variation, and to identify associations with functional zooplankton diversity. We observed that turbidity and increased nutrients influenced the functional composition and functional diversity indices of zooplankton due to aquatic pollution. Eutrophic environments favored more specialized species, with greater selectivity in food capture and greater ability to escape predators. We suggest that eutrophic conditions lead to changes in the functional composition of the assemblies decreasing differentiation and variability of functional traits. Such changes lead to a loss of ecosystem processes and make these ecosystems more vulnerable.

Ephyrae and metaephyrae of Pelagia noctiluca: stage determination, morphometry and shrinkage

Abstract Understanding processes occurring in the different life stages of jellyfish is key to advance knowledge on their trophic interactions and population dynamics. We describe four developmental stages of Pelagia noctiluca ephyrae and metaephyrae based on the progress of feeding structures and morphometric measurements on the central disc diameter and total body diameter. Size differs significantly among stages, but it can overlap substantially, suggesting that it is not always coupled with development progress due to different somatic growth. Morphological distinction of stages is biologically important because it implies different levels of food specialization and capture efficiency. We further report a 25% (±13 SD) shrinkage of ephyrae and metaephyrae after storage in 4% formaldehyde solution. This metric can be used in ecological studies focusing on size-related traits of field observed individuals.