Cooperative feeding is often observed among predators with strong social bonds; however, it is unexpected in solitary predators. During 2016, several mass predation events were witnessed in St ...Andrews Bay and Right Whale Bay, South Georgia, where up to 36 leopard seals (
Hydrurga leptonyx
) were seen feeding together at king penguin (
Aptenodytes patagonicus
) colonies. Three post-mortem prey-processing events were observed where two leopard seals actively fed on the same carcass in an unusual display of tolerance for a species where anti-social behaviour is the norm. The seals were observed repeatedly tearing adult king penguins between themselves, while floating alongside each other at the surface of the water. This is the first record of co-feeding in this difficult-to-study species; however, it is expected that the behaviour is rare within the population. We propose that the high density of predators combined with the readily available prey, makes it costlier to defend a kill than it is to tolerate kleptoparasitism. It is unclear whether this behaviour shows cooperative feeding, which would likely enable more efficient prey processing: by holding the prey in their jaws, each seal provides an anchor on the prey that others can pull against to stretch and tear it.
The origin of baleen whales (Mysticeti), the largest animals on Earth, is closely tied to their signature filter-feeding strategy. Unlike their modern relatives, archaic whales possessed a ...well-developed, heterodont adult dentition. How these teeth were used, and what role their function and subsequent loss played in the emergence of filter feeding, is an enduring mystery. In particular, it has been suggested that elaborate tooth crowns may have enabled stem mysticetes to filter with their postcanine teeth in a manner analogous to living crabeater and leopard seals, thereby facilitating the transition to baleen-assisted filtering. Here we show that the teeth of archaic mysticetes are as sharp as those of terrestrial carnivorans, raptorial pinnipeds and archaeocetes, and thus were capable of capturing and processing prey. By contrast, the postcanine teeth of leopard and crabeater seals are markedly blunter, and clearly unsuited to raptorial feeding. Our results suggest that mysticetes never passed through a tooth-based filtration phase, and that the use of teeth and baleen in early whales was not functionally connected. Continued selection for tooth sharpness in archaic mysticetes is best explained by a feeding strategy that included both biting and suction, similar to that of most living pinnipeds and, probably, early toothed whales (Odontoceti).
Today, monachine seals display the largest body sizes in pinnipeds. However, the evolution of larger body sizes has been difficult to assess due to the murky taxonomic status of fossil seals, ...including fossils referred to
, a species thought to be present on both sides of the North Atlantic during the Neogene. Several studies have recently called into question the taxonomic validity of these fossils, especially those from the USA, as the fragmentary lectotype specimen from Belgium is of dubious diagnostic value. We find that the lectotype isolated humerus of
is too uninformative; thus, we designate
as a nomen dubium. More complete cranial and postcranial specimens from the Pliocene Yorktown Formation are described as a new taxon,
. The cranial specimens display adaptations towards an enhanced ability to cut or chew prey that are unique within Phocidae, and estimates indicate
to be around 2.83 m in length. A parsimony phylogenetic analysis found
is a crown monachine. An ancestral state estimation of body length indicates that monachines did not have a remarkable size increase until the evolution of the lobodontins and miroungins.
Mammalian carnivores rely on their sharp teeth to effectively kill and consume prey. However, over time this causes wear and breakage that alters tooth shape, reducing their effectiveness. Extreme ...tooth wear and damage is especially prevalent in species that scavenge carcasses, like the Tasmanian devil (Sarcophilus harrisii), which are well known for their voracious appetites and ability to consume almost all of a carcass, including bone. In this study, we comprehensively describe tooth wear in captive and wild devils to look for differences in the patterns and rate of wear between these environments. To do this we surveyed tooth condition in skulls from 182 wild and 114 captive devils for which age was estimated using canine over‐eruption. We found the types of tooth wear documented were the same in captive and wild devils, but captive animals have less severe wear than wild devils of the same estimated age. There was no difference in the proportion of captive or wild individuals with broken canine or molar teeth; however, breakage occurred at a younger age in wild devils. Although not considered anomalous or harmful, this indicates a difference in the way teeth are being used and/or the foods consumed between captive and wild devils. We hypothesize how these results relate to differences in diet or behavior that may stem from their various feeding environments, for example, higher quality food (fresh, whole, and yet to be scavenged carcasses) provided to captive devils likely causes less wear. Further, we support management options that closely replicate wild diet items and behaviors suitable for a long‐term insurance population.
We found differences in intensity and rate of tooth wear between captive and wild Tasmanian devils, where captive devils have less severe wear than wild devils of the same estimate age. Although not considered anomalous or harmful, this indicates a difference in the way the teeth are being used and/or the types of food being consumed.
Highlights
The types of tooth wear documented were the same in captive and wild devils.
However, captive animals have less severe wear and wear their teeth at a lower rate than wild devils of the same estimated age.
This likely results from differences in diet or behavior that may stem from their various feeding environments.
Percussive underwater signaling in wild gray seals Hocking, David P.; Burville, Ben; Parker, William M. G. ...
Marine mammal science,
April 2020, 2020-04-00, 20200401, Letnik:
36, Številka:
2
Journal Article
Reply to comment by Kienle et al. 2017 Hocking, David P.; Marx, Felix G.; Park, Travis ...
Proceedings of the Royal Society. B, Biological sciences,
09/2017, Letnik:
284, Številka:
1863
Journal Article
A predator's preferred prey often changes over the course of its life as it grows from an inexperienced juvenile through to a sexually mature adult. For species with highly specialised feeding ...strategies, this may require its anatomy to change over the course of its life. The dugite (Pseudonaja affinis, Günther 1872) is a venomous snake from Australia that displays such a diet shift, with juveniles feeding on small reptiles, while adults mainly target mammals. We examined the morphology of fangs across both sexes and throughout ontogeny using geometric morphometrics and cross‐sectional sharpness measurements of key functional regions on these teeth. This highlighted key differences in shape that likely relate to the varied properties of their adult and juvenile diet. We found that juveniles display a more robust and blunter fang, which likely relates to feeding on scaly lizard prey, whereas adults have slender fangs with sharper tips, which reflects their diet of softer mammalian prey. There were also differences between males and females, with male snakes having significantly more slender fangs than females, which might be an indication of niche partitioning between the sexes. Using snout‐vent length as a proxy for age, we found that the ontogenetic shift in fang shape occurs when P. affinis is around 60 cm long, corresponding with previous studies that found this size to be the moment where these snakes switch from their juvenile to adult diet.
The fangs of the snake Pseudonaja affinis are found to vary in shape throughout their lives. This ensures their fangs are mechanically optimised for their dominant prey type, be it scaly prey as juveniles, or soft‐skinned prey as adults.
More than 1 in 10 adults in the general population experience chronic widespread body pain (CWP), which lies at one end of a continuous spectrum of pain ranging in both severity and duration. ...Neuroendocrine factors can modify the effect of known psychological and psychosocial risk factors for progression along the spectrum of pain and development of CWP, and genetic variants that affect neuroendocrine and neural processing potentially affect susceptibility to chronic pain development. We have examined variants across genes encoding the beta2-adrenergic receptor (ADRB2) and catecholamine-O-methyltransferase (COMT) - key neuroendocrine signalling factors - in a large population-based sample to determine whether these may be involved in pain progression and CWP development. A nested association study was conducted using individuals from the 1958 British Birth Cohort Study who had been assessed for pain status. Genotypes were available for nine single nucleotide polymorphisms (SNPs) across ADRB2 and 11 SNPs across COMT. ADRB2 SNPs rs12654778 and rs1042713 were associated either with CWP alone (p=0.02 for both) or with position along pain spectrum (pain status; p=0.04). Common functional ADRB2 haplotype combinations were also associated with pain status (p(model)=0.002) and, further, with both extent and duration of pain (p(model)=0.003 and p(model)=0.002, respectively). There were no associations of either CWP or pain status with COMT genotypes or haplotypes. These results are the first to suggest that functional ADRB2 variants are involved in regulating pain status at a population level. A role for COMT in chronic pain development was not identified, though could not be excluded.
Pinnipeds generally target relatively small prey that can be swallowed whole, yet often include larger prey in their diet. To eat large prey, they must first process it into pieces small enough to ...swallow. In this study we explored the range of prey‐processing behaviors used by Australian sea lions (Neophoca cinerea) when presented with large prey during captive feeding trials. The most common methods were chewing using the teeth, shaking prey at the surface, and tearing prey held between the teeth and forelimbs. Although pinnipeds do not masticate their food, we found that sea lions used chewing to create weak points in large prey to aid further processing and to prepare secured pieces of prey for swallowing. Shake feeding matches the processing behaviors observed in fur seals, but use of forelimbs for “hold and tear” feeding has not been previously reported for other otariids. When performing this processing method, prey was torn by being stretched between the teeth and forelimbs, where it was secured by being squeezed between the palms of their flippers. These results show that Australian sea lions use a broad repertoire of behaviors for prey processing, which matches the wide range of prey species in their diet.
The polymeric immunoglobulin receptor (pIgR) maintains the integrity of epithelial barriers by transporting polymeric antibodies and antigens through the epithelial mucosa into the lumen. In this ...study, we examined the role of pIgR in maintaining gut barrier integrity, which is important for the normal development in mice.
Cohorts of pIgR
mice and their wildtype controls were housed under Specific Pathogen Free (SPF) conditions and monitored for weight gain as an indicator of development over time. The general physiology of the gastrointestinal tract was analysed using immunohistochemistry in young (8-12 weeks of age) and aged mice (up to 18 months of age), and the observed immunopathology in pIgR
mice was further characterised using flow cytometry. Urinary metabolites were analysed using gas chromatography-mass spectrometry (GC-MS), which revealed changes in metabolites that correlated with age-related increase in gut permeability in pIgR
mice.
We observed that pIgR
mice exhibited delayed growth, and this phenomenon is associated with low-grade gut inflammation that increased with ageing. The gross intraepithelial lymphocytic (IEL) infiltration characteristic of pIgR
mice was redefined as CD8α
αβ
T cells, the majority of which expressed high levels of CD103 and CD69 consistent with tissue resident memory T cells (T
). Comparison of the urinary metabolome between pIgR
and wild-type mice revealed key changes in urinary biomarkers fucose, glycine and Vitamin B5, suggestive of altered mucosal permeability. A significant increase in gut permeability was confirmed by analysing the site-specific uptake of sugar probes in different parts of the intestine.
Our data show that loss of the secretory antibody system in mice results in enhanced accumulation of inflammatory IELs in the gut, which likely reflects ongoing inflammation in reaction to gut microbiota or food antigens, leading to delayed growth in pIgR
mice. We demonstrate that this leads to the presence of a unique urinary metabolome profile, which may provide a biomarker for altered gut permeability.
PDF
