Comparative terrestrial locomotion of the Hooker's sea lion (Phocarctos hookeri) and the New Zealand fur seal (Arctocephalus forsteri): evolutionary and ecological implications

Beentjes, Michael P.

doi:10.1111/j.1096-3642.1990.tb01204.x

Cited by 31 publications

(25 citation statements)

References 42 publications

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“…Polasek et al (2006) found a Mb gradient in harbor seal epaxial muscles, and regions of increased Mb loads were associated with areas that generate more propulsive power while swimming. Equivalent Mb levels in adult NFS Pec and LD muscles may reflect heavy use of the hindlimbs and LD for quadrupedal terrestrial locomotion (Beentjes 1990). Similar Mb loads between muscles and/or the reduced Mb in pups might also be due to MHC isoform composition.…”

Section: Discussionmentioning

confidence: 99%

Development of the aerobic dive limit and muscular efficiency in northern fur seals (Callorhinus ursinus)

et al. 2011

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Northern fur seal (Callorhinus ursinus; NFS) populations have been declining, perhaps due to limited foraging ability of pups. Because a marine mammal's proficiency at exploiting underwater prey resources is based on the ability to store large amounts of oxygen (O(2)) and to utilize these reserves efficiently, this study was designed to determine if NFS pups had lower blood, muscle, and total body O(2) stores than adults. Pups (<1-month old) had a calculated aerobic dive limit only ~40% of adult females due to lower blood and, to a much greater extent, muscle O(2) stores. Development of the Pectoralis (Pec) and Longissimus dorsi (LD) skeletal muscles was further examined by determining their myosin heavy chain (MHC) composition and enzyme activities. In all animals, the slow MHC I and fast-twitch IIA proteins typical of oxidative fiber types were dominant, but adult muscles contained more (Pec ~50%; LD ~250% higher) fast-twitch MHC IID/X protein characteristic of glycolytic muscle fibers, than pup muscles. This suggests that adults have greater ability to generate muscle power rapidly and/or under anaerobic conditions. Pup muscles also had lower aerobic and anaerobic ATP production potential, as indicated by lower metabolically scaled citrate synthase, β-hydroxyacyl CoA dehydrogenase, and lactate dehydrogenase activities (all P values ≤0.001). In combination, these findings indicate that pups are biochemically and physiologically limited in their diving capabilities relative to adults. This may contribute to lower NFS first year survival.

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Section: Discussionmentioning

confidence: 99%

Development of the aerobic dive limit and muscular efficiency in northern fur seals (Callorhinus ursinus)

et al. 2011

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“…Here we suggest that including these types of information in the model can help improve accuracies. Sea lions as a class differ from fur seals in several aspects of body locomotion, and allowing the model to distinguish between the two might explain some of the model improvement [61]. It may also be explained by differences in prey processing tactics that we observed the species using [62], as this type of behaviour was not examined in the dogs.…”

Section: Discussionmentioning

confidence: 99%

Seeing It All: Evaluating Supervised Machine Learning Methods for the Classification of Diverse Otariid Behaviours

et al. 2016

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Constructing activity budgets for marine animals when they are at sea and cannot be directly observed is challenging, but recent advances in bio-logging technology offer solutions to this problem. Accelerometers can potentially identify a wide range of behaviours for animals based on unique patterns of acceleration. However, when analysing data derived from accelerometers, there are many statistical techniques available which when applied to different data sets produce different classification accuracies. We investigated a selection of supervised machine learning methods for interpreting behavioural data from captive otariids (fur seals and sea lions). We conducted controlled experiments with 12 seals, where their behaviours were filmed while they were wearing 3-axis accelerometers. From video we identified 26 behaviours that could be grouped into one of four categories (foraging, resting, travelling and grooming) representing key behaviour states for wild seals. We used data from 10 seals to train four predictive classification models: stochastic gradient boosting (GBM), random forests, support vector machine using four different kernels and a baseline model: penalised logistic regression. We then took the best parameters from each model and cross-validated the results on the two seals unseen so far. We also investigated the influence of feature statistics (describing some characteristic of the seal), testing the models both with and without these. Cross-validation accuracies were lower than training accuracy, but the SVM with a polynomial kernel was still able to classify seal behaviour with high accuracy (>70%). Adding feature statistics improved accuracies across all models tested. Most categories of behaviour -resting, grooming and feeding—were all predicted with reasonable accuracy (52–81%) by the SVM while travelling was poorly categorised (31–41%). These results show that model selection is important when classifying behaviour and that by using animal characteristics we can strengthen the overall accuracy.

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“…). The walrus and otariid seals maintain the ability to locomote on land using all four flippers, which allows them to perform quadrupedal terrestrial gaits with the ability to locomote rapidly on land (Peterson and Bartholomew , English , Gordon , King , Beentjes ). However, phocid seals have become more constrained for terrestrial locomotion due to their greater aquatic specialization.…”

Section: Discussionmentioning

confidence: 99%

“…The inability to move the hind limbs under the body of the seal, transformation of the limbs into flippers, use of the hind flippers as the primary aquatic propulsor, and the development of a more streamlined body are just a few of the features that have enabled phocids to become highly aquatically derived (Howell 1930, Ray 1963, Fish et al 1988. The walrus and otariid seals maintain the ability to locomote on land using all four flippers, which allows them to perform quadrupedal terrestrial gaits with the ability to locomote rapidly on land (Peterson and Bartholomew 1967, English 1976, Gordon 1981, King 1983, Beentjes 1990). However, phocid seals have become more constrained for terrestrial locomotion due to their greater aquatic specialization.…”

Section: Discussionmentioning

confidence: 99%

Kinematics of terrestrial locomotion in harbor seals and gray seals: Importance of spinal flexion by amphibious phocids

Garrett

Fish

2014

Marine Mammal Science

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Pinnipeds are amphibious mammals with flippers, which function for both aquatic and terrestrial locomotion. Evolution of the flippers has placed constraints on the terrestrial locomotion of phocid seals. The detailed kinematics of terrestrial locomotion of gray (Halichoerus grypus) and harbor (Phoca vitulina) seals was studied in captivity and in the wild using video analysis. The seals exhibited dorsoventral undulations with the chest and pelvis serving as the main contact points. An anteriorly directed wave produced by spinal flexion aided in lifting the chest off the ground as the fore flippers were retracted to pull the body forward. The highest length-specific speeds recorded were 1.02 BL/s for a gray seal in captivity and 1.38 BL/s for a harbor seal in the wild. The frequency and amplitude of spinal movement increased directly with speed, but the duty factor remained constant. Substrate did not influence the kinematics except for differences due to moving up or down slopes. The highly aquatic nature of phocids seals has restricted them to locomote on land primarily using spinal flexion, which can limit performance in speed and duration.

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Comparative terrestrial locomotion of the Hooker's sea lion (Phocarctos hookeri) and the New Zealand fur seal (Arctocephalus forsteri): evolutionary and ecological implications

Cited by 31 publications

References 42 publications

Development of the aerobic dive limit and muscular efficiency in northern fur seals (Callorhinus ursinus)

Development of the aerobic dive limit and muscular efficiency in northern fur seals (Callorhinus ursinus)

Seeing It All: Evaluating Supervised Machine Learning Methods for the Classification of Diverse Otariid Behaviours

Kinematics of terrestrial locomotion in harbor seals and gray seals: Importance of spinal flexion by amphibious phocids

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