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Long-distance migrations allow animals to exploit seasonal prey opportunities and track favorable oceanographic conditions. The basking shark (Cetorhinus maximus) is a large, filter-feeding elasmobranch commonly observed in temperate shelf habitats, though it is known to seasonally occupy warmer, lower-latitude regions. In the Northwest Atlantic Ocean, basking sharks migrate from summer habitats on the continental shelf of the northeastern United States and Canada to the tropical waters of the Caribbean and South America during winter. However, the functional role of these large-scale movements is poorly understood, and their overwintering behavior during migration remains enigmatic. Here, we use pop-up satellite archival transmitting (PSAT) tags to measure basking shark vertical habitat use during this migration. Based on daily summaries of time-at-depth and time-at-temperature, we find that sharks exhibited two main behaviors: shallow epipelagic occupancy on or near the continental shelf and movements throughout the mesopelagic in offshore waters. While offshore, vertical habitat use was characterized by a strong diel vertical migration (DVM) that overlapped with primary and secondary deep scattering layers, particularly in the southern Sargasso Sea. However, DVM behavior was widespread throughout the Sargasso Sea, where most tagged individuals overwintered, and continued into the Caribbean and during trans-equatorial movements. Our results suggest basking sharks likely forage throughout these large-scale migrations, rather than relying primarily on energy stores as has been suggested for other highly migratory shark species. We also suggest that basking sharks may regularly target prey biomass in a deeper, often non-migratory prey layer below the primary deep scattering layer. These findings highlight the potential ecological importance of mesopelagic prey for basking sharks during migration and contribute to growing recognition of the ecosystem services supported by deep-pelagic food webs within and beyond the primary deep scattering layer.

Biologging and telemetry have transformed our understanding of marine megafauna movement ecology. Yet, methodological constraints continue to limit data quality and deployment duration. Devices recording whale shark (Rhincodon typus) behaviours and movements have been used for decades, but they remain challenging to deploy and vary in success. Recently, spring-loaded clamp-based systems have emerged as one of the most widely used approaches to attach electronic tags to the fins of this globally endangered species. Currently, however, no consensus guidelines exist as to how to optimise this approach, potentially leading to continued underperforming deployments limiting analysis potential. Here, we synthesise experiences with clamp-based tagging worldwide through a targeted survey of whale shark researchers. We explore performance and challenges with a view to propose current best practices in the field. Whale shark researcher responses to the survey highlighted clamp-based systems as a practical and more widely applicable approach than drill-based methods, which are often used to secure tags to other large sharks. They also noted that clamps have greater retention potential and are suitable for a wider range of tags compared to dart-based methods, but are still constrained by design, placement, and deployment conditions. Researchers used a variety of materials and designs to build their own clamps, often facilitated by direct collaboration with each other or key manufacturers. Clamps produced highly variable outcomes, ranging from successful long-term satellite transmissions over 200 days and short-term biologging for 48 h at 20 Hz, to premature detachment and cases of fin damage. For long-term clamps, changes in position on the fin allowed for more stable satellite transmissions over time. Some clamp designs achieved data quantity and quality close to that of drilled deployments, demonstrating their potential to rival traditional methods while offering a less invasive approach. Results emphasised the ongoing need for technological refinement and rigorous evaluation of clamp performance and associated impacts. Based on collective insights, we present a unified approach to clamp design and positioning, and identify key priorities for advancing this attachment technology, such as aiming for positions b-2 and c-2 on the fin and ensuring the clamp bridge distance (always between 30 and 50 mm) and tension are matched to shark size. Optimising clamp systems could substantially improve our ability to generate high-quality, long-duration movement data while minimising tagging impacts on the animal where possible. This could enhance ecological and conservation research outcomes for endangered whale sharks, with broader implications for tagging other large-bodied marine megafauna. The online version contains supplementary material available at 10.1186/s40317-026-00462-4.

Shark species are among the most vulnerable marine fishes facing impacts from fisheries. To ensure the international fin trade does not threaten their populations, several species have been listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) Appendix II. However, the lack of data on fin-to-body weight ratios makes it difficult to accurately estimate the biomass of harvested sharks based on their traded fins and weakens CITES enforcement. This study determines species-specific fin-to-body weight ratios for shark species caught by the artisanal fishery in the southern Gulf of Mexico. Wet fin weights of primary fins from 479 individuals, belonging to 19 species and six families, indicated that Carcharhinus leucas (43.6%), C. plumbeus (18.8%), C. obscurus (15.0%) and Sphyrna lewini (6.6%) were the most significant large-bodied species involved in the international shark fin trade from the southern Gulf of Mexico. The species-specific mean wet fin weight to total body weight ratios ranged from 1.22% to 3.44%, while wet fin weight to trunk weight ratios varied between 1.40% and 5.73%. Furthermore, the dry fin weight-to-trunk weight ratios oscillated from 0.52% to 1.71%, and the dry fin weight-to-trunk weight ratios ranged from 0.58% to 2.86%. The mean dry-to-wet fin conversion factor was estimated at 42.9%. Alopias superciliosus, C. altimus, C. leucas, C. obscurus, C. plumbeus and Isurus paucus exhibited the highest fin-to-body weight ratios. Our findings provided a practical tool for assessing shark population exploitation based on shark fin trade volumes, contributing to CITES enforcement and management strategies.

Chondrichthyans are among the most ancient vertebrates, and their morphology has enabled adaptation to diverse marine environments. In sharks, the head is the functional center for feeding, respiration, and sensory perception, reflecting a balance between phylogenetic constraints and ecological demands. Striking specializations, such as the cephalofoil of hammerhead sharks or the elongated rostrum of sawsharks, illustrate remarkable adaptations. Most studies on head shape have focused on single species or restricted clades, whereas broader analyses have focused on parts of the skull. We analyzed the ventral head morphology of 453 shark species (Selachii), focusing on the relative position of the rostrum, mouth, and nostrils (in a subset of 395 species), using standardized illustrations and landmark-based geometric morphometrics. Shape variation was related to ecological and anatomical factors. The morphological space reveals a phylogenetic signal, with reconstructed ancestral shapes close to the overall mean configuration, indicating strong morphological conservatism. Evolutionary model fitting supports Brownian motion dynamics with limited divergence from ancestral forms. Correlations with habitat and body size are weak, whereas stronger associations are observed with the number of olfactory lamellae. Our results provide a large-scale comparative framework of ventral head morphology in sharks, highlighting its evolutionary stability and predominant phylogenetic control.

Aiming at the inherent limitations of the basic White Shark Optimizer (WSO), such as insufficient population diversity, unbalanced global and local search mechanisms, and weak convergence in the later stage, this paper proposes an Improved White Shark Optimizer (IWSO). The algorithm is improved from the following three aspects: Firstly, the Tent chaotic map is introduced to replace the traditional random initialization in the population initialization stage. Secondly, an adaptive nonlinear convergence factor and a dynamic inertia weight adjustment strategy are designed to focus on the fine search in the neighborhood of the optimal solution. Thirdly, the Levy flight perturbation mechanism and the elite opposition-based learning strategy are integrated to expand the search range and further accelerate the convergence speed. To verify the effectiveness and superiority of the IWSO algorithm, the CEC2017 test suite is selected for simulation experiments, and the IWSO is systematically compared with seven other representative swarm intelligence algorithms. The experimental results show that the IWSO is significantly superior to all comparison algorithms in multiple evaluation indicators, including minimum makespan, average convergence value, standard deviation, and successful convergence rate, on scheduling instances of different scales and difficulties. The convergence curve remains leading throughout the iteration process and shows a smoother convergence trend. The multi-strategy enhanced white shark optimizer proposed in this paper effectively overcomes the inherent defects of the basic algorithm, significantly improves the solution accuracy and convergence efficiency of the job shop scheduling problem, and has high theoretical research value and practical engineering application prospects. In the future, the multi-strategy improved White Shark Optimizer will be extended to multi-objective job shop scheduling, dynamic disturbance job shop scheduling, and large-scale production scheduling scenarios with numerous workpieces and machines.

Sharks and rays are among the most threatened vertebrates; yet, mechanistic data to predict their responses to climate change remain sparse. We argue that the epaulette shark (Hemiscyllium ocellatum) is a tractable candidate species for conservation physiology because it is small and benthic, abundant on Great Barrier Reef flats, exceptionally tolerant of hypoxia and acidification conditions, and amenable to captive breeding and experimental work across life stages. Its distinctive appearance, accessibility and calm disposition also make it an effective flagship species for public engagement and reef conservation. A long-term breeding colony and field access have enabled experiments spanning ocean acidification, hypoxia and warming. Across studies, epaulette sharks show robust maintenance of routine behaviours in both adult and juvenile stages under elevated CO2, consistent with physiological traits that buffer pH changes. In contrast, warming imposes clear constraints, especially early in ontogeny. Embryos hatch earlier and smaller, aerobic scope narrows, metabolic costs rise, recovery is delayed, growth is impaired, and mortality risk increases at the upper thermal range. Adults and juveniles retain notable hypoxia tolerance, reflecting nocturnal tidepool conditions; yet, performance trade-offs may emerge when warming and low O2 co-occur. Together, findings so far illustrate how a resilient species can still harbour critical vulnerabilities under projected climate change conditions. Here, we outline how the epaulette shark can anchor comparative work to derive transferable thresholds (e.g. temperature-oxygen safety margins), test cross-tolerance mechanisms and validate field-relevant biomarkers for monitoring population health. Management applications follow directly, allowing habitat-specific thermal and oxygen limits for shallow flats and nursery areas to be identified, informing heatwave response and water-quality targets, and refining husbandry and welfare guidelines for research and public aquaria. While a site-attached benthic model will not capture constraints faced by pelagic elasmobranchs, leveraging this tractable flagship species to bridge mechanistic understanding and management decision points can enhance forecasts for other reef-associated chondrichthyans and support climate-ready conservation strategies.

This study presents the first morphometric examination of the pectoral fins of 19 shark species in the Libyan Mediterranean Sea using 88 specimens collected from November 2023 to November 2024. The observed morphometrics successfully differentiate between benthic Squatiniformes, demersal Squalidae, triakis, and pelagic lamnids and carcharhinids. Statistical analysis revealed significant interspecific variation (p < 0.05) in different calculated ratios, with the highest level of discrimination power being shown by PL/PF and PA/PB. Multivariate data analyses also supported unique morphological groupings of ecologically and phylogenetically close members. The present study also recorded significant biogeographical information with five shark species being first reported in Libyan waters: Heptranchias perlo (Bonnaterre, 1788), Squalus megalops (Macleay, 1881), Carcharhinus altimus (Springer, 1950), Carcharhinus obscurus (Lesueur, 1818), and Squalus mitsukurii (Jordan and Snyder, 1903). It is noteworthy that S. mitsukurii was first reported in the entire Mediterranean Sea, a considerable expansion of its known range. These results are important to emphasize the ecological significance of the area and make further observations to improve our knowledge of shark diversity and distribution in the southern Mediterranean. In addition, the present findings help to underline the high diagnostic significance of pectoral-fin morphometrics and the usefulness of the present methods for species identification and shark biodiversity in the southern Mediterranean Sea.

Predation and its risk influence the ecology and evolution of both predator and prey species. Despite this, predatory attempts of large apex sharks on cetaceans often remain unobserved, constraining empirical assessments of their frequency and ecological significance. Shark bite scars can be used as an indirect measure to quantify predation risk on dolphins and may reveal species-specific and spatial patterns of predator-prey interactions. Here, we analysed photographs of coastal dolphins in southeast Queensland, Australia to compare predation risk between multiple dolphin species across differing habitats. Using fresh wounds, bites were mainly attributed to tiger (Galeocerdo cuvier) and white (Carcharodon carcharias) sharks, with the peduncle being the most bitten body region across all species. Shark bite scarring differed between species: 50.3% of Australian humpback (Sousa sahulensis), 27.7% of Indo-Pacific bottlenose (Tursiops aduncus) and 38.5% of common bottlenose (Tursiops truncatus) exhibited scars. Dolphins had more scars in sheltered waters (42.6%) compared to open waters (16.3%). Generalised linear models confirmed S. sahulensis were more susceptible to predation attempts, with non-calves in sheltered waters most at risk. These findings provide a baseline for current predation risk across multiple habitats of sympatric dolphin species in Queensland, providing insight into drivers of the predator-prey interactions.

Sleeper sharks (family Somniosidae) are large, slow-growing deep-sea sharks that are rarely documented in the southeastern Pacific, and records from the Chilean waters have remained taxonomically uncertain. Here, we report a confirmed record of a large-bodied southern Somniosus from northern Chile based on a gravid female incidentally captured by a commercial deep-sea longline fishery off Antofagasta and a late-stage male embryo aborted during handling. The embryo measured 90.5 cm in total length and exhibited morphological and meristic characters consistent with large-bodied S. antarcticus, including a cylindrical body, short rounded snout, spineless dorsal fins, hook-like dermal denticles, and a 40-turn spiral valve. Additionally, a 639&#xa0;bp fragment of the mitochondrial cytochrome C oxidase subunit I (COI) gene was obtained from both the female and embryo, and the two sequences were identical, consistent with maternal inheritance. Comparative analyses using public records placed the Chilean haplotype within the large-bodied Somniosus species complex. The Chilean haplotype was identical to an Antarctic record labelled S. pacificus and differed by two substitutions from a New Zealand record labelled S. antarcticus. However, the COI does not fully resolve species boundaries within the pacificus/antarcticus complex, as the divergence between nominal species remains low. These results provide the first well-documented record of the Antarctic sleeper shark in northern Chile and expand the documented occurrence of southern large-bodied Somniosus along the Chilean margin. More broadly, this record highlights the importance of integrating internal meristics, morphology, and molecular data when documenting rare deep-sea sharks in fishery bycatch.

In May of 2022, an aquarium-maintained broadnose sevengill shark (Notorynchus cepedianus) developed proliferative skin lesions that prompted pathologic and molecular investigation. Histopathologic examination revealed epidermal hyperplasia consisting of proliferation of spinous epithelial cells with mild dysplasia. Metagenomic sequencing identified a novel adomavirus with an 18,834 base pair circular double-stranded DNA genome. The virus, provisionally named broadnose sevengill shark adomavirus (7AdoV), contains two bidirectionally expressed protein-coding gene sets. Genomic annotation and structural predictions of proteins were used to contextualize 7AdoV phylogenetically and functionally. Transcriptomic analysis showed that expression of the structural late gene set was higher than the replicative early gene set at the time of diagnostic sampling. In situ hybridization using RNAscope technology localized transcripts of the adomavirus Wasp gene to epithelial cells of the hyperplastic epidermis. Infection by this novel adomavirus was associated with superficial and proliferative lesions that were self-limiting and resolved in this shark.

Ecological associations such as mutualism, commensalism and parasitism strongly influence animal fitness and ecosystem structure, yet they remain poorly understood in the open ocean. Ecological interdependence means that the loss of one species can trigger co-declines and accelerate biodiversity loss. Large, mobile animals often host smaller 'companion' species that gain benefits such as protection from predation, foraging opportunities, or host-mediated transport through close association. We quantified companion-host associations among seven shark species present across three ocean basins. This is the first large-scale assessment to investigate how environmental conditions and marine protected-area (MPA) status shape these associations. Data on species identity, abundance and length were obtained from a curated database derived from midwater Baited Remote Underwater Video Systems (BRUVS). Almost half of individual sharks hosted companions, with marked variation among species. Companions were most common on Australian blacktip sharks (Carcharhinus tilstoni) and least common on scalloped hammerheads (Sphyrna lewini). Companion presence was best predicted by sea surface temperature, salinity, wind speed and distance to shore, while companion abundance was predicted by primary productivity, wind speed and salinity. Several of these environmental factors are highly sensitive to climate change, potentially disrupting companion-host associations. Partially protected areas (IUCN IV-VI) had a higher probability of companion occurrence than areas outside partial protection, whereas highly protected areas (IUCN I-II) supported greater companion abundance when companions were present. Declining host populations and changing environmental conditions may disrupt companion associations, removing the interspecies linkages and increasing the risk of co-decline of dependent species. Effective protection of these associations will support the persistence of biodiversity and ecological processes in the open ocean.

The Greenland shark (Somniosus microcephalus) is a deep-sea vertebrate inhabiting the cold waters of the North Atlantic and Arctic Ocean and is renowned for its exceptional longevity, with individuals estimated to live for more than 400&#x2009;years. It has also been proposed as a candidate species exhibiting negligible senescence. This narrative review synthesizes current knowledge on the biological mechanisms that may contribute to this phenotype. Potential contributing factors include its extreme environment, low metabolic rate and remarkably late sexual maturation, all of which may reduce cumulative physiological stress over time. At the molecular level, recent genomic studies have identified distinctive features, including duplications of DNA repair genes and structural variation in the tumour suppressor protein p53, which are consistent with enhanced genome maintenance, although their functional significance remains to be experimentally validated. Additional mechanisms, such as proteostatic resilience, antioxidant defences and immune adaptations, may further support long-term cellular homeostasis. Collectively, these observations suggest that the Greenland shark possesses biological characteristics that could influence multiple hallmarks of ageing, including genomic stability, proteostasis and intercellular communication. Emerging evidence also indicates resistance to age-related functional decline in systems such as vision and cardiac function. Taken together, these characteristics highlight the Greenland shark as a valuable, yet still underexplored, model for investigating the biology of longevity and resistance to ageing. Further research in this species may provide insights into the mechanisms underlying healthy ageing across vertebrates and generate hypotheses for future translational studies.

Rare earth elements and yttrium (REY) signatures in stromatolitic carbonates have emerged as powerful geochemical proxies for reconstructing paleo-depositional environments of microbial habitats. The applicability of such a proxy relies on the assumption that REY substitutes for calcium into crystal lattices, directly reflecting the composition of the fluid from which the carbonate precipitated. The REY signatures of stromatolites are often similar to those of open ocean seawater. In restricted environments, however, REY fractionation can occur between waters and stromatolites, questioning their reliability to reconstruct microbial habitats through Earth's history. In this contribution, we determined the REY concentrations and partition coefficients (Kd(stromatolite-fluid)) of sub-recent stromatolitic carbonates and ambient waters from the hypersaline Hamelin Pool in the Shark Bay lagoon, Australia. Shale-normalized REY patterns of stromatolite morphologies show (except colloform morphologies) a middle REYSN enrichment relative to the light and heavy REYSN. These signatures differ from those of seawater and ambient waters, suggesting that today's waters cannot be directly compared with stromatolitic carbonates from Shark Bay, which formed over thousands of years in a complex microbial mat system. Stromatolite morphologies such as colloform, smooth, or pustular structures formed in supratidal and intertidal environments exhibit the most variable Kd(stromatolite-fluid) values for the REY. The most dominant process affecting REY geochemistry in the Shark Bay stromatolites is most likely organic matter degradation and subsequent REY release into porewaters from which the carbonates formed in a (semi)closed microbial mat system. Cerebroid structures of the deepest lagoonal environment in the subtidal zone show the most constant Kd(stromatolite-fluid) values throughout the REY series, reflecting the least closed microbial mat system and a direct relationship between stromatolite morphology and water chemistry.

Fish-cubomedusa associations are less frequently reported than those involving scyphozoans and are typically limited to larval or juvenile fishes without an explicit predator context. Here, we report an adult Monodactylus argenteus associated with the cubozoan Morbakka sp. during an encounter with a carcharhinid shark at Magnetic Island, Australia. Throughout the observation, the fish maintained close association with the cubomedusa and reduced its distance to the bell and upper tentacle field during the shark encounter. Although behavioural motivations could not be determined from aerial observations alone, the observed change in spatial positioning by the fish was consistent with refuge use. This observation extends previous reports of fish-cubomedusa associations by documenting such an interaction in an adult fish during an encounter with a carcharhinid shark.

Whale sharks (Rhincodon typus) are migratory species known to form temporary coastal aggregations in regions of high plankton density, such as Bah&#xed;a de los &#xc1;ngeles (BLA), Mexico. Due to various anthropogenic threats, the species is classified as vulnerable, underscoring the need for effective and non-invasive monitoring strategies. This study explores the integration of drone-based remote sensing with deep learning (DL) techniques for the automated recognition and tracking of whale sharks. In October 2023, 59 drone flights-42 from boats and 17 from land-were conducted, resulting in 23 recorded sightings. Two DL-based approaches were implemented: DeepLabCut (DLC), based on pose estimation, and multi-scale patch (MSP), based on image region classification. Both strategies employed convolutional neural networks, with data augmentation and transfer learning techniques to enhance performance. The most effective model, MSP with multi-size and overlapping patches, achieved a macro F1 score of 0.91 and a covered area metric of 0.65. Statistical analysis indicated that environmental and operational factors-including turbidity, solar glare and external agents-had minimal impact on predictive performance. These results highlight the potential of DL-enhanced drone monitoring for scalable, accurate and non-invasive recognition and tracking of whale sharks, supporting ecological research and conservation efforts in BLA and comparable marine environments.

Penetrating thoracic trauma accounts for only 1%-13% of chest injury hospitalizations but is associated with high mortality due to involvement of the heart, great vessels, and lungs. Among these, foreign body injuries with retained objects are rare, and the role of specific structural features such as barbs in limiting injury severity has not been well described. A 54-year-old male sustained a penetrating injury to the right anterior chest from a barbed shark dart while fishing. On admission, he was relatively stable but with compensated hemodynamics. Echocardiography showed pericardial effusion with signs of early tamponade. Chest CT confirmed that the cylindrical foreign body had traversed the chest wall, the middle lobe of the right lung, and the pericardium, with the tip abutting the right atrial wall. Emergency median sternotomy revealed that the barbed shark dart had penetrated the right lung and pericardium and reached the right atrium. Notably, the backward-facing barbs at the posterior end of the dart prevented further forward migration, thereby averting perforation of the posterior right atrial wall and catastrophic bleeding. The foreign body was removed, the atrial puncture site was repaired, and a wedge resection of the injured lung was performed. The patient recovered uneventfully and remained asymptomatic at 1-year follow-up. This case highlights a unique "self-limiting" mechanism of penetrating cardiac injury, in which the barbed structure of the foreign body paradoxically reduced the extent of cardiac damage. Injury patterns in penetrating thoracic trauma depend heavily on the kinetic energy and structural characteristics of the object. For stable patients, a multidisciplinary approach involving imaging-guided surgical planning is critical.

The International Union for Conservation of Nature (IUCN) Red List of Threatened Species is a critical measure of global aquatic and terrestrial biodiversity status. It is also the basis for the Red List Index, which tracks extinction risk over time. Sharks, rays, and chimaeras (Chondrichthyes) have now been comprehensively assessed twice (1996-2011 and 2012-2021) with hindcast assessments from 1970 onward, yielding an unprecedented extinction risk trajectory for an aquatic vertebrate class. The three-decade success of the IUCN Species Survival Commission (SSC) Shark Specialist Group (SSG) in providing updated and evidence-based assessments stems from sustained and coordinated activities by SSG members. We examined how a community of dedicated experts organized to fill gaps in key information to inform Red List assessments. From this evaluation, we identified six key lessons related to membership, taxonomic changes, implementation of the precautionary approach, information prioritization, assessment standardization, and policy efforts. However, existing challenges, including resource constraints and assessment discrepancies at different spatial scales, need to be addressed to ensure Red List assessments stay on pace with advances in conservation. With the second global assessment of chondrichthyans completed, it is appropriate to reflect on the evolution of the SSG and its achievements over three decades to highlight new tools and approaches to red listing and to identify priorities for the immediate future that are also applicable to other aquatic taxa with limited data, slow life histories, and exposure to high levels of fishing. Conclusiones extra&#xed;das de tres d&#xe9;cadas de evaluaciones de la Lista Roja de la UICN que impulsan la conservaci&#xf3;n de tiburones, rayas y quimeras Resumen La Lista Roja de Especies Amenazadas de la Uni&#xf3;n Internacional para la Conservaci&#xf3;n de la Naturaleza (UICN) es un indicador fundamental del estado de la biodiversidad acu&#xe1;tica y terrestre a nivel mundial. Tambi&#xe9;n constituye la base del &#xcd;ndice de la Lista Roja, que da seguimiento al riesgo de extinci&#xf3;n a lo largo del tiempo. Los tiburones, las rayas y las quimeras (Chondrichthyes) han sido evaluados exhaustivamente en dos ocasiones (1996&#x2013;2011 y 2012&#x2013;2021), con evaluaciones retrospectivas a partir de 1970, lo que ha permitido obtener una trayectoria del riesgo de extinci&#xf3;n sin precedentes para una clase de vertebrados acu&#xe1;ticos. El &#xe9;xito de tres d&#xe9;cadas del Grupo de Especialistas en Tiburones (SSG) de la Comisi&#xf3;n de Supervivencia de Especies (SSC) de la UICN en proporcionar evaluaciones actualizadas y basadas en evidencia se debe a las actividades sostenidas y coordinadas de los miembros del SSG. Examinamos c&#xf3;mo una comunidad de expertos comprometidos se organiz&#xf3; para llenar las brechas en la informaci&#xf3;n clave necesaria para fundamentar las evaluaciones de la Lista Roja. A partir de esta evaluaci&#xf3;n, identificamos seis lecciones clave relacionadas con la membres&#xed;a, los cambios taxon&#xf3;micos, la implementaci&#xf3;n del enfoque de precauci&#xf3;n, la priorizaci&#xf3;n de la informaci&#xf3;n, la estandarizaci&#xf3;n de las evaluaciones y los esfuerzos en materia de pol&#xed;ticas. Sin embargo, es necesario abordar los desaf&#xed;os existentes, entre ellos las limitaciones de recursos y las discrepancias en las evaluaciones a diferentes escalas espaciales, para garantizar que las evaluaciones de la Lista Roja se mantengan al d&#xed;a con los avances en conservaci&#xf3;n. Ahora que se ha completado la segunda evaluaci&#xf3;n global de los condrictios, es oportuno reflexionar sobre la evoluci&#xf3;n del SSG y sus logros a lo largo de tres d&#xe9;cadas para destacar nuevas herramientas y enfoques para la inclusi&#xf3;n en la Lista Roja e identificar prioridades para el futuro inmediato que tambi&#xe9;n sean aplicables a otros taxones acu&#xe1;ticos con datos limitados, ciclos de vida lentos y expuestos a altos niveles de pesca.

This study presents the first direct dietary assessment of a juvenile whale shark (Rhincodon typus) using DNA recovered from its stomach content. A DNA metabarcoding library for the 18S gene showed the most abundant prey were cnidarians (Class Anthozoa, 43.4%, including soft corals and sea pens) and crustaceans (Class Hexanauplia, 40.2%, represented by four orders of copepods). These results expand the breadth of items present in the diet of whale sharks and underscore gaps in understanding the trophic ecology and habitat use of elusive and threatened marine megafauna.

Echinorhiniformes and Echinorhinidae are a distinct order and family of sharks comprising two species showing several outstanding morphological characteristics, such as their tooth morphologies. Their teeth display unique shapes among sharks with main and secondary cusps which also allow tracking the fossil record of Echinorhinidae. In this study, we review the dental morphological characters of Echinorhinus spp. and further analyse intraspecific morphological variation in a population tentatively identified as E. cf. brucus from the Indian Ocean. Previously suggested hypotheses of intra- and interspecific morphological variations are critically tested, i.e., we examine ontogenetic changes in dental morphologies in E. cf. brucus and test for species-specific differences of dental morphologies between E. brucus, E. cf. brucus, and E. cookei. Results show that within and between species dental variation is limited. Neither tooth size nor cusp angle are jaw position specific. An ontogenetic change in cusplet numbers is detected. Species-specific dental morphological differences within the examined specimens of Echinorhinus were not found; however, the overall tooth formula may be a useful character for species identification. Further, our tooth measurements are useful for estimating the average total length of specimens, which, in combination with the detected ontogenetic change in cusplet numbers, we suggest using for the characterization of the fossil record of Echinorhinus.