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"Seals"
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Seals and pups
Seals live on both land and sea, and these adorable animals take special care with their pups. Early readers will discover how seals love to eat fish, and how mother seals bring food to their newborn pups.
Book
Taking animal tracking to new depths: synthesizing horizontal-vertical movement relationships for four marine predators
In animal ecology, a question of key interest for aquatic species is how changes in movement behavior are related in the horizontal and vertical dimensions when individuals forage. Alternative theoretical models and inconsistent empirical findings mean that this question remains unresolved. Here we tested expectations by incorporating the vertical dimension (dive information) when predicting switching between movement states (\"resident\" or \"directed\") within a state-space model. We integrated telemetry-based tracking and diving data available for four seal species (southern elephant, Weddell, antarctic fur, and crabeater) in East Antarctica. Where possible, we included dive variables derived from the relationships between (1) dive duration and depth (as a measure of effort), and (2) dive duration and the postdive surface interval (as a physiological measure of cost). Our results varied within and across species, but there was a general tendency for the probability of switching into \"resident\" state to be positively associated with shorter dive durations (for a given depth) and longer postdive surface intervals (for a given dive duration). Our results add to a growing body of literature suggesting that simplistic interpretations of optimal foraging theory based only on horizontal movements do not directly translate into the vertical dimension in dynamic marine environments. Analyses that incorporate at least two dimensions can test more sophisticated models of foraging behavior.
Journal Article
Genomic analyses reveal trans-generational haul out site fidelity in leopard seals
As top predators, leopard seals (
Hydrurga leptonyx
) have a key role in Southern Ocean ecosystems. For example, this species has driven the local collapse of Antarctic fur seals (
Arctocephalus gazella)
at Cape Shirreff, in the northern Antarctic Peninsula. However, little is known about leopard seal haul out site fidelity and social behavior. Here, we employ “genomic tagging” and relatedness analyses from a genome-wide single nucleotide polymorphism (SNP) dataset obtained from 88 leopard seal tissue samples to investigate patterns of seasonal haul out site fidelity and social structure at Cape Shirreff, a leopard seal hotspot during austral summers. Although many seals were observed only once, some females had remarkably high site fidelity returning to the same location across timeframes of up to eight years. Most leopard seals were unrelated, but we identified a trio of closely related females, including a mother-daughter pair, indicating that seasonal site fidelity can span generations. Interestingly, the mother leopard seal identified through our relatedness analyses is a foraging specialist that targets Antarctic fur seal pups; her diet changed very little over the past decade. Our findings suggest high individual variability in leopard seal behavior regarding site fidelity and social structure. Such flexibility may play a key role in this species’ responses to environmental change.
Journal Article
Highly Pathogenic Avian Influenza A(H5N1) Virus Outbreak in New England Seals, United States
We report the spillover of highly pathogenic avian influenza A(H5N1) into marine mammals in the northeastern United States, coincident with H5N1 in sympatric wild birds. Our data indicate monitoring both wild coastal birds and marine mammals will be critical to determine pandemic potential of influenza A viruses.
Journal Article
Seals
\"With their sleek, powerful bodies allowing them to dive far beneath the surface, seals are among the ocean's most dangerous hunters. Readers will learn all about the lives of these magnificent mammals, from how they socialize and find mates to what they eat and how their senses work. They will also discover the man-made dangers that many seal species are facing today.\"--Amazon.com.
Book
A model for maxilloturbinate morphogenesis in seals
The nasal cavities of mammals contain the maxilloturbinate bones, which are involved in reducing heat and water losses. The maxilloturbinates of Arctic seals develop into particularly elaborate labyrinthine patterns, which are well adapted to retain heat and moisture from exhaled gas. These structures develop prenatally and continue to grow postnatally. The developmental mechanism of labyrinthine patterning is unknown. Here we report a model of maxilloturbinate pattern formation in prenatal and juvenile seals based on a simple algorithmic description and three key parameters: target turbinate porosity, characteristic ossification time scale, and typical gestation time scale. Under a small set of geometrical and physical rules, our model reproduces key features of the patterns observed in the turbinate structure of three seal species. To validate our model, we measure complexity, hydraulic diameter, backbone fractal dimension, and Horton-Strahler statistics for a rigorous quantitative comparison with actual tomograms of grey and harp seal skull specimens. Our model closely replicates the structural development of seal turbinates in these respects. Labyrinthine maxilloturbinate development may depend on the ability for neighbouring bone branches to detect and avoid each other, potentially through the mechanosensing of shear stresses from amniotic fluid and air flow.
Journal Article
Elephant seal
\"Engaging images accompany information about elephant seals. The combination of high-interest subject matter and narrative text is intended for students in grades 3 through 7\"-- Provided by publisher.
Book
Hydrodynamic perception in true seals (Phocidae) and eared seals (Otariidae)
Pinnipeds, that is true seals (Phocidae), eared seals (Otariidae), and walruses (Odobenidae), possess highly developed vibrissal systems for mechanoreception. They can use their vibrissae to detect and discriminate objects by direct touch. At least in Phocidae and Otariidae, the vibrissae can also be used to detect and analyse water movements. Here, we review what is known about this ability, known as hydrodynamic perception, in pinnipeds. Hydrodynamic perception in pinnipeds developed convergently to the hydrodynamic perception with the lateral line system in fish and the sensory hairs in crustaceans. So far two species of pinnipeds, the harbour seal (Phoca vitulina) representing the Phocidae and the California sea lion (Zalophus californianus) representing the Otariidae, have been studied for their ability to detect local water movements (dipole stimuli) and to follow hydrodynamic trails, that is the water movements left behind by objects that have passed by at an earlier point in time. Both species are highly sensitive to dipole stimuli and can follow hydrodynamic trails accurately. In the individuals tested, California sea lions were clearly more sensitive to dipole stimuli than harbour seals, and harbour seals showed a superior trail following ability as compared to California sea lions. Harbour seals have also been shown to derive additional information from hydrodynamic trails, such as motion direction, size and shape of the object that caused the trail (California sea lions have not yet been tested). The peculiar undulated shape of the harbour seals’ vibrissae appears to play a crucial role in trail following, as it suppresses self-generated noise while the animal is swimming.
Journal Article