| microbes, metagenomes and marine mammals: enabling the next generation of scientist to enter the genomic era. | the revolution in dna sequencing technology continues unabated, and is affecting all aspects of the biological and medical sciences. the training and recruitment of the next generation of researchers who are able to use and exploit the new technology is severely lacking and potentially negatively influencing research and development efforts to advance genome biology. here we present a cross-disciplinary course that provides undergraduate students with practical experience in running a next gener ... | 2013 | 24007365 |
| insights from venous oxygen profiles: oxygen utilization and management in diving california sea lions. | the management and depletion of o2 stores underlie the aerobic dive capacities of marine mammals. the california sea lion (zalophus californianus) presumably optimizes o2 store management during all dives, but approaches its physiological limits during deep dives to greater than 300 m depth. blood o2 comprises the largest component of total body o2 stores in adult sea lions. therefore, we investigated venous blood o2 depletion during dives of california sea lions during maternal foraging trips t ... | 2013 | 23926312 |
| behavioral responses of california sea lions to mid-frequency (3250-3450 hz) sonar signals. | military sonar has the potential to negatively impact marine mammals. to investigate factors affecting behavioral disruption in california sea lions (zalophus californianus), fifteen sea lions participated in a controlled exposure study using a simulated tactical sonar signal (1 s duration, 3250-3450 hz) as a stimulus. subjects were placed into groups of three and each group received a stimulus exposure of 125, 140, 155, 170, or 185 db re: 1 μpa (rms). each subject was trained to swim across an ... | 2013 | 24183102 |
| pharmacokinetics of ceftiofur crystalline-free acid (excede sterile suspension) administered via intramuscular injection in wild california sea lions (zalophus californianus). | the pharmacokinetics of ceftiofur crystalline-free acid (excede sterile suspension, 200 mg ceftiofur equivalents/ml) were determined for the california sea lion (zalophus californianus). a single dose of excede was administered intramuscularly at 6.6 mg/kg to 12 wild california sea lions during rehabilitation. the first 10 animals were each assigned to two blood collection time points, with a total of 10 time points at: 6, 12, 24, 48, 72, 96, 120, 144, 168, and 192 hr after administration of the ... | 2013 | 24063100 |
| insights into the life history and ecology of a large shortfin mako shark isurus oxyrinchus captured in southern california. | in june 2013, a record-breaking female isurus oxyrinchus (total length 373 cm, mass 600 kg) was captured by rod and reel off huntington beach, california, where it was subsequently donated to research and provided a rare opportunity to collect the first data for a female i. oxyrinchus of this size. counts of vertebral band pairs estimate the shark to have been c. 22 years old, depending upon assumptions of band-pair deposition rates, and the distended uteri and spent ovaries indicated that this ... | 2015 | 25998058 |
| development of a serological assay for the sea lion (zalophus californianus) anellovirus, zcav. | new diseases in marine animals are emerging at an increasing rate, yet methodological limitations hinder characterization of viral infections. viral metagenomics is an effective method for identifying novel viruses in diseased animals; however, determining virus pathogenesis remains a challenge. a novel anellovirus (zalophus californianus anellovirus, zcav) was recently reported in the lungs of captive california sea lions involved in a mortality event. zcav was not detected by pcr in the blood ... | 2015 | 25965294 |
| sea lions' (zalophus californianus) use of human pointing gestures as referential cues. | this experiment investigated the ability of four human-socialized sea lions to exploit human communicative gestures in three different object-choice tasks based on directional cues emitted by their caretakers. in study 1, three of the tested subjects were able to generalize their choice of the pointed target to variations of the basic pointing gestures (i.e., cross-body point, elbow point, foot point, and gaze only), from the very first trials. study 2 showed that the subjects could follow the p ... | 2015 | 25678395 |
| hippocampal neuropathology of domoic acid-induced epilepsy in california sea lions (zalophus californianus). | california sea lions (zalophus californianus) are abundant human-sized carnivores with large gyrencephalic brains. they develop epilepsy after experiencing status epilepticus when naturally exposed to domoic acid. we tested whether sea lions previously exposed to da (chronic da sea lions) display hippocampal neuropathology similar to that of human patients with temporal lobe epilepsy. hippocampi were obtained from control and chronic da sea lions. stereology was used to estimate numbers of nissl ... | 2014 | 24638960 |
| foraging strategies of a generalist marine predator inhabiting a dynamic environment. | intraspecific variability is increasingly recognized as an important component of foraging behavior that can have implications for both population and community dynamics. we used an individual-level approach to describe the foraging behavior of an abundant, generalist predator that inhabits a dynamic marine ecosystem, focusing specifically on the different foraging strategies used by individuals in the same demographic group. we collected data on movements and diving behavior of adult female cal ... | 2016 | 27651228 |
| the temporomandibular joint of california sea lions (zalophus californianus): part 2-osteoarthritic changes. | following comprehensive characterization of the temporomandibular joint (tmj) of the california sea lion, as well demonstrating that tmj-osteoarthritis (oa) occurs in this species, the objective of this part of the investigation was to describe the macroscopic osteologic findings associated with tmj-oa in a large museum collection of skull specimens. | 2015 | 25451465 |
| the temporomandibular joint of california sea lions (zalophus californianus): part 1 - characterisation in health and disease. | this study aimed to characterise the histologic, biomechanical and biochemical properties of the temporomandibular joint (tmj) of california sea lions. in addition, we sought to identify structure-function relationships and to characterise tmj lesions found in this species. | 2015 | 25451464 |
| the kinematics of the california sea lion foreflipper during forward swimming. | to determine the two-dimensional kinematics of the california sea lion foreflipper during thrust generation, a digital, high-definition video is obtained using a non-research female sea lion at the smithsonian national zoological park in washington, dc. the observational videos are used to extract maneuvers of interest--forward acceleration from rest using the foreflippers and banked turns. single camera videos are analyzed to digitize the flipper during the motions using 10 points spanning root ... | 2014 | 25378293 |
| evidence for a genetic basis of urogenital carcinoma in the wild california sea lion. | although neoplasia is a major cause of mortality in humans and domestic animals, it has rarely been described in wildlife species. one of the few examples is a highly prevalent urogenital carcinoma in california sea lions (csls). although the aetiology of this carcinoma is clearly multifactorial, inbreeding depression, as estimated using levels of microsatellite multilocus heterozygosity, is identified as predictive for this neoplasia. on further analysis, this relationship appears to be largely ... | 2014 | 25339718 |
| cross-modal transitivity in a california sea lion (zalophus californianus). | the ability of an experimentally experienced female california sea lion to form transitive relations across sensory modalities was tested using a matching-to-sample procedure. the subject was trained by trial-and-error, using differential reinforcement, to relate an acoustic sample stimulus to one member from each of two previously established visual classes. once the two auditory-visual relations were formed, she was tested to determine whether untrained transitive relations would emerge betwee ... | 2014 | 24337783 |
| auditory detection of ultrasonic coded transmitters by seals and sea lions. | ultrasonic coded transmitters (ucts) are high-frequency acoustic tags that are often used to conduct survivorship studies of vulnerable fish species. recent observations of differential mortality in tag control studies suggest that fish instrumented with ucts may be selectively targeted by marine mammal predators, thereby skewing valuable survivorship data. in order to better understand the ability of pinnipeds to detect uct outputs, behavioral high-frequency hearing thresholds were obtained fro ... | 2014 | 25234996 |
| object permanence in marine mammals using the violation of expectation procedure. | object permanence refers to the ability to process information about objects even when they are not visible. one stage of object permanence, called visible displacement, involves being able to find an object that has been fully hidden from view. visible displacement has been demonstrated in many animal species, yet very little is known about object permanence in marine mammals. in addition, the methodology for testing visible displacement has sometimes been called into question because alternati ... | 2015 | 25193351 |
| food limitation of sea lion pups and the decline of forage off central and southern california. | california sea lions increased from approximately 50 000 to 340 000 animals in the last 40 years, and their pups are starving and stranding on beaches in southern california, raising questions about the adequacy of their food supply. we investigated whether the declining sea lion pup weight at san miguel rookery was associated with changes in abundance and quality of sardine, anchovy, rockfish and market squid forage. in the last decade off central california, where breeding female sea lions fro ... | 2016 | 27069651 |
| development of a real-time pcr for the detection of pathogenic leptospira spp. in california sea lions. | several real-time pcr assays are currently used for detection of pathogenic leptospira spp.; however, few methods have been described for the successful evaluation of clinical urine samples. this study reports a rapid assay for the detection of pathogenic leptospira spp. in california sea lions zalophus californianus using real-time pcr with primers and a probe targeting the lipl32 gene. the pcr assay had high analytic sensitivity-the limit of detection was 3 genome copies per pcr volume using l ... | 2014 | 25114040 |
| transformation of the genital epithelial tract occurs early in california sea lion development. | an unusually high prevalence of metastatic urogenital carcinoma has been observed in free-ranging california sea lions stranded off the coast of california in the past two decades. no cases have been reported for sea lions in the relatively unpolluted gulf of california. we investigated occurrence of genital epithelial transformation in 60 sea lions (n=57 pups and 3 adult females) from the gulf of california and examined whether infection by a viral pathogen previously found to be associated wit ... | 2016 | 27069641 |
| toxicokinetics of domoic acid in the fetal rat. | domoic acid (da) is a potent neurotoxin that has both marine wildlife and human health impacts, including developmental effects during prenatal exposure in rodent models. however, little is known regarding da toxicokinetics in the fetal unit during maternal-fetal transfer. tissue distribution and toxicokinetics of da were investigated in pregnant rats and their pups just prior to birth at gestational day 20. pregnant sprague dawley rats were given an intravenous dose of 1.0 mg da/kg and samples ... | 2012 | 22306965 |
| oxidative stress and redistribution of glutamine synthetase in california sea lions (zalophus californianus) with domoic acid toxicosis. | the aim of this study was to test the hypothesis that oxidative stress and glutamine synthetase (gs) redistribution occur in domoic acid (da) toxicosis in california sea lions (csls, zalophus californianus). sections of archived hippocampi from seven control and 13 csls diagnosed with da toxicosis were labelled immunohistochemically for gs and for two markers of oxidative stress, malondialdehyde (mda) and 3-nitrotyrosine (nt). the distribution and intensity of labelling were compared with the pa ... | 2014 | 24060152 |
| intraperitoneal dextrose administration as an alternative emergency treatment for hypoglycemic yearling california sea lions (zalophus californianus). | the marine mammal center (tmmc) cares for malnourished california sea lion (csl) (zalophus californianus) pups and yearlings every year. hypoglycemia is a common consequence of malnutrition in young csls. administering dextrose during a hypoglycemic crisis is vital to recovery. traditional veterinary approaches to treat hypoglycemia pose therapeutic challenges in otariids, as vascular access and catheter maintenance can be difficult. the current approach to a hypoglycemic episode at tmmc is to a ... | 2016 | 27010266 |
| the use of surrogate data in demographic population viability analysis: a case study of california sea lions. | reliable data necessary to parameterize population models are seldom available for imperiled species. as an alternative, data from populations of the same species or from ecologically similar species have been used to construct models. in this study, we evaluated the use of demographic data collected at one california sea lion colony (los islotes) to predict the population dynamics of the same species from two other colonies (san jorge and granito) in the gulf of california, mexico, for which de ... | 2015 | 26413746 |
| proteomic analysis of cerebrospinal fluid in california sea lions (zalophus californianus) with domoic acid toxicosis identifies proteins associated with neurodegeneration. | proteomic studies including marine mammals are rare, largely due to the lack of fully sequenced genomes. this has hampered the application of these techniques toward biomarker discovery efforts for monitoring of health and disease in these animals. we conducted a pilot label-free lc-ms/ms study to profile and compare the cerebrospinal fluid from california sea lions with domoic acid toxicosis (dat) and without dat. across 11 samples, a total of 206 proteins were identified (fdr<0.1) using a comp ... | 2015 | 26364553 |
| trihalomethanes in marine mammal aquaria: occurrences, sources, and health risks. | disinfecting water containing the high levels of dissolved organic carbon (doc) commonly generated during pinniped husbandry may cause the formation of carcinogenic disinfection byproducts (dbps). little information is available on dbp levels, sources, and health risks in marine mammal aquaria. using the commonly observed trihalomethanes (thms) as a dbp indicator, we monitored concentrations for seven months at the marine mammal center in sausalito, california, one of the largest pinniped rehabi ... | 2014 | 24805374 |
| senile plaques and cerebral amyloid angiopathy in an aged california sea lion (zalophus californianus). | senile plaques (sps) and cerebral amyloid angiopathy (caa) consisting of β-amyloid (aβ) are major features in the brain of alzheimer's disease (ad) patients and elderly humans and animals. in this study, we report the finding of sps and caa in an aged sea lion (30 years), which is the first demonstration of ad-related pathological changes in a marine animal. histologically, sps were observed at the cerebral cortex, most frequently at the frontal lobe, with two morphologically different types: th ... | 2014 | 24779910 |
| dental pathology of the california sea lion (zalophus californianus). | skulls from 1,085 california sea lions (zalophus californianus) were examined macroscopically according to defined criteria. the museum specimens, 61.8% male and 37.3% female, were acquired from strandings and varied in age from juvenile to adult. the majority of teeth were available for examination (95.7%); 3.8% of teeth were artefactually absent, 0.4% deemed absent due to acquired tooth loss and 0.1% were congenitally absent. acquired tooth loss was associated significantly with sex (p = 0.004 ... | 2014 | 24725510 |
| a california sea lion (zalophus californianus) can keep the beat: motor entrainment to rhythmic auditory stimuli in a non vocal mimic. | is the ability to entrain motor activity to a rhythmic auditory stimulus, that is "keep a beat," dependent on neural adaptations supporting vocal mimicry? that is the premise of the vocal learning and synchronization hypothesis, recently advanced to explain the basis of this behavior (a. patel, 2006, musical rhythm, linguistic rhythm, and human evolution, music perception, 24, 99-104). prior to the current study, only vocal mimics, including humans, cockatoos, and budgerigars, have been shown to ... | 2013 | 23544769 |
| gas bubble disease in the brain of a living california sea lion (zalophus californianus). | a yearling california sea lion (zalophus californianus) was admitted into rehabilitation with signs of cerebellar pathology. diagnostic imaging that included radiography and magnetic resonance imaging (mri) demonstrated space-occupying lesions predominantly in the cerebellum that were filled partially by csf-like fluid and partially by gas, and cerebral lesions that were fluid filled. over a maximum period of 4 months, the brain lesions reduced in size and the gas resorbed and was replaced by cs ... | 2013 | 23372553 |
| the binaural click-evoked auditory brainstem response of the california sea lion (zalophus californianus). | auditory brainstem responses (abrs) elicited by high-amplitude [100 db re 20 μpa, peak-to-peak equivalent sound pressure level (pespl)] aerial broadband clicks were collected from seven california sea lions in order to provide a basic description of short-latency auditory evoked potentials in this species. the waveform of the abr was similar to that of other mammals, comprising seven positive and six negative characteristic waves. variability in the amplitudes and latencies of waves was higher a ... | 2013 | 23297929 |
| clinical relevance of novel otarine herpesvirus-3 in california sea lions (zalophus californianus): lymphoma, esophageal ulcers, and strandings. | herpesviruses have been recognized in marine mammals, but their clinical relevance is not always easy to assess. a novel otarine herpesvirus-3 (othv3) was detected in a geriatric california sea lion (zalophus californianus), and using a newly developed quantitative pcr assay paired with histology, othv3 was associated with esophageal ulcers and b cell lymphoblastic lymphoma in this animal. the prevalence and quantities of othv3 were then determined among buffy coats from 87 stranded and managed ... | 2012 | 23234600 |
| 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 convergen ... | 2013 | 23180048 |
| temporal summation of airborne tones in a california sea lion (zalophus californianus). | the trade-off between sound level and duration on hearing sensitivity (temporal summation) was investigated in a california sea lion (zalophus californianus) using airborne pure-tone stimuli. thresholds were behaviorally measured using the method of constant stimuli at 2.5, 5, and 10 khz for nine signal durations ranging from 25 to 500 ms. in general, thresholds decreased as duration increased up to 300 ms, beyond which thresholds did not significantly improve. when these data were fitted separa ... | 2012 | 23145636 |
| characterization of ocular gland morphology and tear composition of pinnipeds. | the importance of tear film integrity to ocular health in terrestrial mammals is well established, however, in marine mammals, the role of the tear film in protection of the ocular surface is not known. in an effort to better understand the function of tears in maintaining health of the marine mammal eye surface, we examined ocular glands of the california sea lion and began to characterize the biochemical nature of the tear film of pinnipeds. | 2013 | 23067374 |
| evaluation of circulating eosinophil count and adrenal gland function in california sea lions naturally exposed to domoic acid. | to determine the effect of natural exposure to domoic acid (da) on eosinophil counts and adrenal gland function in california sea lions (zalophus californianus). | 2012 | 23013509 |
| lung collapse in the diving sea lion: hold the nitrogen and save the oxygen. | lung collapse is considered the primary mechanism that limits nitrogen absorption and decreases the risk of decompression sickness in deep-diving marine mammals. continuous arterial partial pressure of oxygen profiles in a free-diving female california sea lion (zalophus californianus) revealed that (i) depth of lung collapse was near 225 m as evidenced by abrupt changes in during descent and ascent, (ii) depth of lung collapse was positively related to maximum dive depth, suggesting that the se ... | 2012 | 22993241 |
| a cupric silver histochemical analysis of domoic acid damage to olfactory pathways following status epilepticus in a rat model for chronic recurrent spontaneous seizures and aggressive behavior. | the amnesic shellfish toxin, domoic acid, interferes with glutamatergic pathways leading to neuronal damage, most notably causing memory loss and seizures. in this study, the authors utilized a recently developed rat model for domoic acid-induced epilepsy, an emerging disease appearing in california sea lions weeks to months after poisoning, to identify structural damage that may lead to a permanent epileptic state. sprague dawley rats were kindled with several low hourly intraperitoneal doses o ... | 2013 | 22821366 |
| risk factors associated with perianesthetic mortality of stranded free-ranging california sea lions (zalophus californianus) undergoing rehabilitation. | the objective of this study was to identify risk factors associated with perianesthetic mortality of stranded free-ranging california sea lions (zalophus californianus) undergoing rehabilitation. hospital records of california sea lions that underwent heavy sedation or general anesthesia from 2004 through 2008 were reviewed, including records from 419 anesthetic events. procedures that resulted in death during or in the subsequent 72 hr of anesthesia were classified as cases (n = 15). procedures ... | 2012 | 22779225 |
| a novel antibody-based biomarker for chronic algal toxin exposure and sub-acute neurotoxicity. | the neurotoxic amino acid, domoic acid (da), is naturally produced by marine phytoplankton and presents a significant threat to the health of marine mammals, seabirds and humans via transfer of the toxin through the foodweb. in humans, acute exposure causes a neurotoxic illness known as amnesic shellfish poisoning characterized by seizures, memory loss, coma and death. regular monitoring for high da levels in edible shellfish tissues has been effective in protecting human consumers from acute da ... | 2012 | 22567140 |
| seasonal variation in blood and muscle oxygen stores attributed to diving behavior, environmental temperature and pregnancy in a marine predator, the california sea lion. | survival depends on an animal's ability to find and acquire prey. in diving vertebrates, this ability is directly related to their physiological capability (e.g. oxygen stores). we studied the seasonal variation in oxygen stores, body temperature and body condition in california sea lions (zalophus californianus) (csl) as a function of seasonal variation in temperature, primary productivity, diving behavior and reproductive stage. during summer, blood oxygen stores were significantly greater and ... | 2012 | 22561663 |
| underwater psychophysical audiogram of a young male california sea lion (zalophus californianus). | auditory evoked potential (aep) data are commonly obtained in air while sea lions are under gas anesthesia; a procedure that precludes the measurement of underwater hearing sensitivity. this is a substantial limitation considering the importance of underwater hearing data in designing criteria aimed at mitigating the effects of anthropogenic noise exposure. to determine if some aspects of underwater hearing sensitivity can be predicted using rapid aerial aep methods, this study measured underwat ... | 2012 | 22559389 |
| multicentric neurofibromatosis with rectal prolapse in a california sea lion (zalophus californianus). | an approximately 31-yr-old california sea lion (zalophus californianus) with a history of chronic visual impairment and corneal disease presented with slow onset, progressive neurologic deficits. treatment for rear flipper paresis was not effective and the animal was euthanatized. histopathologic findings included hepatocellular and biliary neoplasia, ocular amyloidosis, adrenal adenoma and pheochromocytoma, and spinal cord changes consistent with multicentric neurofibromatosis. this is the firs ... | 2012 | 22448517 |
| weak polygyny in california sea lions and the potential for alternative mating tactics. | female aggregation and male territoriality are considered to be hallmarks of polygynous mating systems. the development of genetic parentage assignment has called into question the accuracy of behavioral traits in predicting true mating systems. in this study we use 14 microsatellite markers to explore the mating system of one of the most behaviorally polygynous species, the california sea lion (zalophus californianus). we sampled a total of 158 female-pup pairs and 99 territorial males across t ... | 2012 | 22432039 |
| serum profiling by maldi-tof mass spectrometry as a diagnostic tool for domoic acid toxicosis in california sea lions. | there are currently no reliable markers of acute domoic acid toxicosis (dat) for california sea lions. we investigated whether patterns of serum peptides could diagnose acute dat. serum peptides were analyzed by maldi-tof mass spectrometry from 107 sea lions (acute dat n = 34; non-dat n = 73). artificial neural networks (ann) were trained using maldi-tof data. individual peaks and neural networks were qualified using an independent test set (n = 20). | 2012 | 22429742 |
| evidence of injury caused by gas bubbles in a live marine mammal: barotrauma in a california sea lion zalophus californianus. | a yearling male california sea lion zalophus californianus with hypermetric ataxia and bilateral negative menace reflexes was brought to the marine mammal center, sausalito, california, u.s.a., in late 2009 for medical assessment and treatment. the clinical signs were due to multiple gas bubbles within the cerebellum. these lesions were intraparenchymal, multifocal to coalescing, spherical to ovoid, and varied from 0.5 to 2.4 cm diameter. the gas composed 21.3% of the total cerebellum volume. th ... | 2011 | 22013748 |
| flow sensing by pinniped whiskers. | beside their haptic function, vibrissae of harbour seals (phocidae) and california sea lions (otariidae) both represent highly sensitive hydrodynamic receptor systems, although their vibrissal hair shafts differ considerably in structure. to quantify the sensory performance of both hair types, isolated single whiskers were used to measure vortex shedding frequencies produced in the wake of a cylinder immersed in a rotational flow tank. these measurements revealed that both whisker types were abl ... | 2011 | 21969689 |
| dolphin and sea lion auditory evoked potentials in response to single and multiple swept amplitude tones. | measurement of the auditory steady-state response (assr) is increasingly used to assess marine mammal hearing. these tests normally entail measuring the assr to a sequence of sinusoidally amplitude modulated tones, so that the assr amplitude function can be defined and the auditory threshold estimated. in this study, an alternative method was employed, where the assr was elicited by an amplitude modulated stimulus whose sound pressure level was slowly varied, or "swept," over a range of levels b ... | 2011 | 21877816 |
| latitudinal range influences the seasonal variation in the foraging behavior of marine top predators. | non-migratory resident species should be capable of modifying their foraging behavior to accommodate changes in prey abundance and availability associated with a changing environment. populations that are better adapted to change will have higher foraging success and greater potential for survival in the face of climate change. we studied two species of resident central place foragers from temperate and equatorial regions with differing population trends and prey availability associated to seaso ... | 2011 | 21853081 |
| antemortem diagnosis of a ventricular septal defect in a california sea lion zalophus californianus. | a yearling california sea lion zalophus californianus stranded in poor body condition, and on physical examination a heart murmur was audible bilaterally. the sea lion was diagnosed with a left-to-right shunting membranous ventricular septal defect (vsd) using b-mode, color-flow doppler and continuous-wave doppler echocardiography. a left-to-right intracardiac shunting lesion was confirmed during cardiac angiographic computed tomography. the vsd defect was verified during the necropsy examinatio ... | 2011 | 21553571 |
| california sea lion (zalophus californianus) aerial hearing sensitivity measured using auditory steady-state response and psychophysical methods. | although electrophysiological methods of measuring the hearing sensitivity of pinnipeds are not yet as refined as those for dolphins and porpoises, they appear to be a promising supplement to traditional psychophysical procedures. in order to further standardize electrophysiological methods with pinnipeds, a within-subject comparison of psychophysical and auditory steady-state response (assr) measures of aerial hearing sensitivity was conducted with a 1.5-yr-old california sea lion. the psychoph ... | 2011 | 21476685 |
| acoustic characteristics of ultrasonic coded transmitters for fishery applications: could marine mammals hear them? | ultrasonic coded transmitters (ucts) producing frequencies of 69-83 khz are used increasingly to track fish and invertebrates in coastal and estuarine waters. to address concerns that they might be audible to marine mammals, acoustic properties of ucts were measured off mission beach, san diego, and at the u.s. navy transdec facility. a regression model fitted to vemco uct data yielded an estimated source level of 147 db re 1 μpa spl @ 1 m and spreading constant of 14.0. based on transdec measur ... | 2010 | 21110617 |
| first evidence for adoption in california sea lions. | demographic parameters such as birth and death rates determine the persistence of populations. understanding the mechanisms that influence these rates is essential to developing effective management strategies. alloparental behavior, or the care of non-filial young, has been documented in many species and has been shown to influence offspring survival. however, the role of alloparental behavior in maintaining population viability has not been previously studied. here, we provide the first eviden ... | 2010 | 21079727 |
| hydrodynamic trail following in a california sea lion (zalophus californianus). | the mystacial vibrissae of pinnipeds constitute a sensory system for active touch and detection of hydrodynamic events. harbour seals (phoca vitulina) and california sea lions (zalophus californianus) can both detect hydrodynamic stimuli caused by a small sphere vibrating in the water (hydrodynamic dipole stimuli). hydrodynamic trail following has only been shown in harbour seals. hydrodynamical and biomechanical studies of single vibrissae of the two species showed that the specialized undulate ... | 2011 | 20959994 |
| anatomy of the california sea lion globe. | this study analyzed the morphology of the california sea lion globe to determine what features may contribute to their characteristic visual abilities. | 2010 | 20840092 |
| the cost of male aggression and polygyny in california sea lions (zalophus californianus). | in polygynous mating systems, males often increase their fecundity via aggressive defense of mates and/or resources necessary for successful mating. here we show that both male and female reproductive behavior during the breeding season (june-august) affect female fecundity, a vital rate that is an important determinant of population growth rate and viability. by using 4 years of data on behavior and demography of california sea lions (zalophus californianus), we found that male behavior and spa ... | 2010 | 20808931 |
| undifferentiated high-grade pleomorphic sarcoma in a california sea lion (zalophus californianus). | a tumour located in the pectoral region and the left front flipper was observed in a 29-year-old female california sea lion (zalophus californianus) that died following signs of respiratory disease and inappetence. metastases were present in the lung and adrenal gland. the histological pattern of the tumour was variable. in some areas the tumour consisted of pleomorphic fibroblast-like cells arranged in a storiform pattern, while in other areas it comprised oval or polygonal cells with round to ... | 2011 | 20708196 |
| harbor seal vibrissa morphology suppresses vortex-induced vibrations. | harbor seals (phoca vitulina) often live in dark and turbid waters, where their mystacial vibrissae, or whiskers, play an important role in orientation. besides detecting and discriminating objects by direct touch, harbor seals use their whiskers to analyze water movements, for example those generated by prey fish or by conspecifics. even the weak water movements left behind by objects that have passed by earlier can be sensed and followed accurately (hydrodynamic trail following). while scannin ... | 2010 | 20639428 |
| the role of body size in individual-based foraging strategies of a top marine predator. | body size is an important determinant of the diving and foraging ability in air-breathing marine vertebrate predators. satellite-linked dive recorders were used during 2003-2004 to investigate the foraging behavior of 22 male california sea lions (zalophus californianus, a large, sexually dimorphic otariid) and to evaluate the extent to which body size explained variation among individuals and foraging strategies. multivariate analyses were used to reduce the number of behavioral variables used ... | 2010 | 20462115 |
| short- and long-term population response to changes in vital rates: implications for population viability analysis. | conservation practitioners use demographic population viability analysis (pva) to understand long-term effects of changing demographic rates on population growth rate. sensitivities and elasticities of stage-specific survival and fertility rates provide managers with guidelines on the relative contributions of various life-history stages to long-term population growth. however, short-term patterns, especially single-year effects, of elasticity may be dramatically different from long-term effects ... | 2010 | 20437963 |
| zebrafish seizure model identifies p,p -dde as the dominant contaminant of fetal california sea lions that accounts for synergistic activity with domoic acid. | fetal poisoning of california sea lions (csls; zalophus californianus) has been associated with exposure to the algal toxin domoic acid. these same sea lions accumulate a mixture of persistent environmental contaminants including pesticides and industrial products such as polychlorinated biphenyls (pcbs) and polybrominated diphenyl ethers (pbdes). developmental exposure to the pesticide dichlorodiphenyltrichloroethane (ddt) and its stable metabolite 1,1-bis-(4-chlorophenyl)-2,2-dichloroethene (p ... | 2010 | 20368122 |
| the effects of water temperature on the energetic costs of juvenile and adult california sea lions (zalophus californianus): the importance of skeletal muscle thermogenesis for thermal balance. | as highly mobile marine predators, many pinniped species routinely encounter a wide range of water temperatures during foraging and in association with seasonal, geographical and climatic changes. to determine how such variation in environmental temperature may impact energetic costs in otariids, we determined the thermal neutral zone of adult and juvenile california sea lions (zalophus californianus) by measuring resting metabolic rate using open-flow respirometry. five adult female (body mass ... | 2009 | 19946075 |
| normal morphology and hormone receptor expression in the male california sea lion (zalophus californianus) genital tract. | histomorphology and estrogen alpha (er alpha), and progesterone receptor (pr) expression were evaluated in free-ranging stranded male california sea lions (zalophus californianus). hormone receptor expression was evaluated using an immunohistochemical technique with monoclonal antibodies. estrogen and prs were identified in the efferent ductules, prostate gland, corpus cavernosa, corpus spongiosium, penile urethra, and in the epithelium and stroma of both the penis and prepuce. in some tissues, ... | 2009 | 19768750 |
| the normal genital tract of the female california sea lion (zalophus californianus): cyclic changes in histomorphology and hormone receptor distribution. | changes in reproductive tract histomorphology, and estrogen (eralpha) and progesterone receptor (pr) expression throughout the breeding cycle were evaluated in free-ranging stranded female california sea lions (zalophus californianus). hormone receptor expression in the ovaries, uterus, cervix, and vagina was evaluated using an immunohistochemical technique with monoclonal antibodies. during a large portion of the cycle, ovaries contained both a corpora lutea (cl) and follicles in varying stages ... | 2009 | 19768749 |
| neuroanatomy and volumes of brain structures of a live california sea lion (zalophus californianus) from magnetic resonance images. | the california sea lion (zalophus californianus) has been a focal point for sensory, communication, cognition, and neurological disease studies in marine mammals. however, as a scientific community, we lack a noninvasive approach to investigate the anatomy and size of brain structures in this species and other free-ranging, live marine mammals. in this article, we provide the first anatomically labeled, magnetic resonance imaging-based atlas derived from a live marine mammal, the california sea ... | 2009 | 19768743 |
| hookworm infection, anaemia and genetic variability of the new zealand sea lion. | hookworms are intestinal blood-feeding nematodes that parasitize and cause high levels of mortality in a wide range of mammals, including otariid pinnipeds. recently, an empirical study showed that inbreeding (assessed by individual measures of multi-locus heterozygosity) is associated with hookworm-related mortality of california sea lions. if inbreeding increases susceptibility to hookworms, effects would expectedly be stronger in small, fragmented populations. we tested this assumption in the ... | 2009 | 19605394 |
| tumor morphology and immunohistochemical expression of estrogen receptor, progesterone receptor, p53, and ki67 in urogenital carcinomas of california sea lions (zalophus californianus). | metastatic carcinoma of urogenital origin is a common cause of mortality in free-ranging california sea lions (zalophus californianus). the etiology of this cancer is likely multifactorial, with viral infection, genetic factors, and exposure to environmental organochlorine contaminants possible contributing factors. in this study, expression of estrogen receptor alpha (er alpha), progesterone receptor (pr), p53, and ki67 were evaluated by immunohistochemistry in 12 sea lions with metastatic carc ... | 2009 | 19276047 |
| the role of domoic acid in abortion and premature parturition of california sea lions (zalophus californianus) on san miguel island, california. | domoic acid is a glutaminergic neurotoxin produced by marine algae such as pseudo-nitzschia australis. california sea lions (zalophus californianus) ingest the toxin when foraging on planktivorous fish. adult females comprise 60% of stranded animals admitted for rehabilitation due to acute domoic acid toxicosis and commonly suffer from reproductive failure, including abortions and premature live births. domoic acid has been shown to cross the placenta exposing the fetus to the toxin. to determin ... | 2009 | 19204339 |
| pathological features of amyloidosis in stranded california sea lions (zalophus californianus). | amyloidosis was diagnosed in 26 stranded adult california sea lions between 1983 and 2006 by retrospective case analysis. the kidneys (92.3% of animals), blood vessels (80.7%) and thyroid glands (65.4%) were most commonly affected. macroscopically, affected kidneys were swollen, with pale tan cortices and loss of corticomedullary differentiation. amyloid deposits in the kidney were located in the glomeruli, blood vessels, and peritubular interstitium, most prominently in the outer stripe of the ... | 2009 | 19114281 |
| characterization of a degenerative cardiomyopathy associated with domoic acid toxicity in california sea lions (zalophus californianus). | domoic acid, produced by marine algae, can cause acute and chronic neurologic sequela in california sea lions (zalophus californianus) from acute toxicity or sublethal exposure. eight sea lions, representing acute and chronic cases, both sexes, and all age classes, were selected to demonstrate a concurrent degenerative cardiomyopathy. critical aspects of characterizing the cardiomyopathy by lesion distribution and morphology were the development of a heart dissection and tissue-trimming protocol ... | 2009 | 19112124 |
| determination of a sedative protocol for use in california sea lions (zalophus californianus) with neurologic abnormalities undergoing electroencephalographic examination. | sedation in sea lions exhibiting abnormal neurologic signs may require modification of established sedatior protocols because of the likely interaction between effects of the sedative and physiologic changes in diseased animals the effects of two sedative combinations, 0.07 mg/kg medetomidine and 0.07 mg/kg medetomidine plus 0.2 mg/kg butorphanol, were compared between california sea lions (zalophus californianus) with signs of neurologic dysfunctior (n=33) and without neurologic signs (n=8). se ... | 2008 | 19110694 |
| computed tomographic imaging of the normal immature california sea lion head (zalophus californianus). | different computed tomography (ct) protocols were tested to optimize imaging of the head of the california sea lion. transverse mode images were superior to helical mode images. bone structures were best imaged using 1 mm slice width combined with a high-frequency image reconstruction algorithm and best viewed using a wide window setting. soft tissue structures were generally difficult to differentiate with the exception of the orbital region, which was best imaged using 2mm slice width combined ... | 2016 | 19051645 |
| rapid behavioural diagnosis of domoic acid toxicosis in california sea lions. | domoic acid is a neurotoxic metabolite of widely occurring algal blooms that has caused multiple marine animal stranding events. exposure to high doses of domoic acid, a glutamate agonist, may lead to persistent medial temporal seizures and damage to the hippocampus. california sea lions (zalophus californianus) are among the most visible and frequent mammalian victims of domoic acid poisoning, but rapid, reliable diagnosis in a clinical setting has proved difficult owing to the fast clearance o ... | 2011 | 21389016 |
| risk factors associated with development of poxvirus lesions in hospitalized california sea lions. | to identify risk factors that may predispose california sea lions (zalophus californianus) to development of cutaneous poxvirus nodules during hospitalization in a rehabilitation center. | 2005 | 16121616 |
| surgical resection of an orbital fat prolapse in a california sea lion (zalophus californianus). | a 23-year-old captive female california sea lion (zalophus californianus) developed an inferiotemporal subconjunctival swelling of the right eye. surgical excision of the mass was performed and a diagnosis of orbital fat prolapse was confirmed histopathologically. there was no recurrence of orbital fat prolapse at 15 months post operatively. this is the first known case of orbital fat prolapse in the california sea lion. | 2005 | 16008709 |
| magnetic resonance imaging quality and volumes of brain structures from live and postmortem imaging of california sea lions with clinical signs of domoic acid toxicosis. | our goal in this study was to compare magnetic resonance images and volumes of brain structures obtained alive versus postmortem of california sea lions zalophus californianus exhibiting clinical signs of domoic acid (da) toxicosis and those exhibiting normal behavior. proton density-(pd) and t2-weighted images of postmortem-intact brains, up to 48 h after death, provided similar quality to images acquired from live sea lions. volumes of gray matter (gm) and white matter (wm) of the cerebral hem ... | 2010 | 21133324 |
| secondary amyloidosis and renal failure in a captive california sea lion (zalophus californianus). | a 16-yr-old, captive-born, female california sea lion (zalophus californianus) was evaluated for intermittent lethargy, partial anorexia, and polydipsia of 2 wk duration. the animal was immobilized for physical examination. it was in thin body condition, with multifocal mucosal ulcerations over the caudal and ventral tongue. blood was collected for hematology, serum chemistry, and leptospirosis serology. serum chemistry revealed severe azotemia, mild hyperglycemia, and severe hyperphosphatemia. ... | 2008 | 18634224 |
| changes in blubber contaminant concentrations in california sea lions (zalophus californianus) associated with weight loss and gain during rehabilitation. | california sea lions have high levels of persistent organic pollutants (pops) in their blubber. animals affected by domoic acid fast and refeed during their rehabilitation. we studied the effect of decreases in total body mass (16 +/- 7% of initial body mass) on blubber pop contaminant concentrations and estimated pop burdens during fasting (12 +/- 5 days) in 19 california sea lions. the effect of refeeding (92 +/- 8% of initial body mass) was also investigated. significant increases in the conc ... | 2008 | 18589985 |
| chronic pancreatitis with secondary diabetes mellitus treated by use of insulin in an adult california sea lion. | a 21-year-old neutered male captive california sea lion developed chronic polyuria; polydipsia; polyphagia; accelerated development of existing cataracts; and frequent episodes of gastrointestinal upset including anorexia, signs of abdominal discomfort, diarrhea, and vomiting. | 2008 | 18518815 |
| neuronal migration defect: a case of subcortical heterotopia in a california sea lion. | a 2 and a half-year-old male california sea lion (zalophus californianus) presented with a history of intermittent generalized seizures. magnetic resonance imaging revealed a large focal mass occupying the right cerebral hemisphere with moderate dilatation of the contralateral lateral ventricle. at necropsy, the right cerebral hemispheric white matter was expanded by numerous irregularly shaped, pale pink nodules up to 10 mm in diameter. the overlying cortex was characterized by increased number ... | 2008 | 18487504 |
| onset, growth, and recovery of in-air temporary threshold shift in a california sea lion (zalophus californianus). | a california sea lion (zalophus californianus) was tested in a behavioral procedure to assess noise-induced temporary threshold shift (tts) in air. octave band fatiguing noise was varied in both duration (1.5-50 min) and level (94-133 db re 20 mupa) to generate a variety of equal sound exposure level conditions. hearing thresholds were measured at the center frequency of the noise (2500 hz) before, immediately after, and 24 h following exposure. threshold shifts generated from 192 exposures rang ... | 2007 | 18189581 |
| novel symptomatology and changing epidemiology of domoic acid toxicosis in california sea lions (zalophus californianus): an increasing risk to marine mammal health. | harmful algal blooms are increasing worldwide, including those of pseudo-nitzschia spp. producing domoic acid off the california coast. this neurotoxin was first shown to cause mortality of marine mammals in 1998. a decade of monitoring california sea lion (zalophus californianus) health since then has indicated that changes in the symptomatology and epidemiology of domoic acid toxicosis in this species are associated with the increase in toxigenic blooms. two separate clinical syndromes now exi ... | 2008 | 18006409 |
| galápagos and californian sea lions are separate species: genetic analysis of the genus zalophus and its implications for conservation management. | accurate formal taxonomic designations are thought to be of critical importance for the conservation of endangered taxa. the galápagos sea lion (gsl), being appreciated as a key element of the galápagos marine ecosystem, has lately been listed as 'vulnerable' by the iucn. to date there is, however, hardly any scientific evidence, whether it constitutes a separate entity from its abundant californian neighbour (csl). in this paper, we delineate the taxonomic relationships within the genus zalophu ... | 2007 | 17868473 |
| seasonal variability in otariid energetics: implications for the effects of predators on localized prey resources. | otariids, like other wild mammals, contend with a wide variety of energetic demands across seasons. however, due to the cryptic behaviors of this marine group, few studies have been able to examine longitudinal energetic costs or the potential impact of these costs on seasonal or annual prey requirements. here we evaluated the changes in energy demand and intake of female california sea lions (zalophus californianus) during reproductive (n=2 sea lions) and nonreproductive (n=3) periods. monthly ... | 2013 | 17508338 |
| hookworm enteritis with bacteremia in california sea lion pups on san miguel island. | large breeding populations of california sea lions (zalophus californianus) are located on san miguel and san nicolas islands in the southern california bight. in 2001, there was a substantial increase in pup mortality in late summer and fall. from june 2002 to january 2003, 208 freshly dead pups were examined on san miguel island, the most western of the channel islands off the coast of southern california. tissues from 186 of these pups were examined histologically. the primary lesions in 133 ... | 2007 | 17495302 |
| relation of dental wear to the concentrations of essential minerals in teeth of the california sea lion zalophus californianus californianus. | tooth wear in marine mammals has been attributed to age, feeding habits, behavior, and contaminants. advanced tooth wear in some california sea lions, including some of very young age (<5 yr), in the gulf of california, suggests that there are variations in chemical composition of tooth parts, wherein the concentrations of certain trace minerals might be anomalous, making them more susceptible to erosion. the concentrations of the essential minerals ca, p, k, na, fe, mg, and zn in the dentition ... | 2007 | 17435255 |
| ancient dna analysis of the japanese sea lion (zalophus californianus japonicus peters, 1866): preliminary results using mitochondrial control-region sequences. | in this study, we successfully extracted ancient dna from skeletal remains of the japanese sea lion-a species that is practically extinct-from archaeological sites and determined a partial sequence of its mitochondrial dna control region. a molecular phylogenetic tree constructed by the neighbor-joining (nj) method showed that the sequences from japanese sea lions clustered together, with a high bootstrap value, and that this cluster was closest to the california sea lion cluster. the distinctly ... | 2007 | 17409720 |
| lingual squamous cell carcinoma in a california sea lion (zalophus californianus). | a 28-yr-old female california sea lion (zalophus californianus) in a commercial aquarium developed an ulcerated lingual tumor and died. necropsy revealed a moderately differentiated squamous cell carcinoma. immunohistochemical staining and electron microscopic studies revealed that the tumor cells were strongly positive with anti-keratin-cytokeratin antibody and had abundant tonofibrils and desmosomes. the neoplasm had metastasized to a mandibular lymph node. | 2002 | 12564535 |
| a behaviorally explicit demographic model integrating habitat selection and population dynamics in california sea lions. | although there has been a call for the integration of behavioral ecology and conservation biology, there are few tools currently available to achieve this integration. explicitly including information about behavioral strategies in population viability analyses may enhance the ability of conservation biologists to understand and estimate patterns of extinction risk. nevertheless, most behavioral-based pva approaches require detailed individual-based data that are rarely available for imperiled s ... | 2008 | 18680502 |
| trace metal concentrations in the hair of zalophus californianus pups and their relation to feeding habits. | the levels of six trace metals (hg, se, pb, cu, fe, and zn) were measured in the hair of california sea lion pups from eight rookeries in the gulf of california, with the aim of relating these levels with the animals feeding habits, trophic level, and delta(15)n signatures at each locality. trace metal levels were seen to vary significantly between sample sites as were tendencies associated with feeding habits. mercury concentrations showed a clear positive correlation with trophic level (r = 0. ... | 2008 | 18679589 |
| spatial release from masking of aerial tones in pinnipeds. | in most masking experiments, target signals and sound intended to mask are located in the same position. spatial release from masking (srm) occurs when signals and maskers are spatially separated, resulting in detection improvement relative to when they are spatially co-located. in this study, srm was investigated in a harbor seal, who naturally lacks pinnae, and california sea lion, who possesses reduced pinnae. subjects had to detect aerial tones at 1, 8, and 16 khz in the presence of octave b ... | 2007 | 17348543 |
| transplacental transfer of organochlorines in california sea lions (zalophus californianus). | the transplacental transfer of organochlorines (ocs) in california sea lions (zalophus californianus) was investigated by analyzing blubber samples from 20 female sea lions and their fetuses during the last trimester of pregnancy. a rapid, high-performance liquid chromatographic, photodiode-array method was used to measure blubber concentrations of polychlorinated biphenyls (pcbs), including dioxin-like congeners, as well as ddts and hexachlorobenzene. summed values of pcbs (sigmapcbs), of ddts ... | 2007 | 17269457 |
| total body oxygen stores and physiological diving capacity of california sea lions as a function of sex and age. | a defining physiological capability for air-breathing marine vertebrates is the amount of oxygen that can be stored in tissues and made available during dives. to evaluate the influence of oxygen storage capacity on aerobic diving capacity, we examined the extent to which blood and muscle oxygen stores varied as a function of age, body size and sex in the sexually dimorphic california sea lion, zalophus californianus. we measured total body oxygen stores, including hematocrit, hemoglobin, mchc, ... | 2007 | 17210964 |
| tissue heavy metal concentrations of stranded california sea lions (zalophus californianus) in southern california. | concentrations of nine heavy metals (as, cd, cu, fe, hg, pb, mn, mo and zn) were determined in the hepatic and renal tissues of 80 stranded california sea lions (zalophus californianus). significant age-dependant increases were observed in liver and kidney concentrations of cadmium and mercury, and renal zinc concentrations. hepatic iron concentrations were significantly higher in females than males. animals with suspected domoic acid associated pathological findings had significantly higher con ... | 2007 | 17116350 |
| an analysis of visual oddity concept learning in a california sea lion (zalophus californianus). | we tested a california sea lion for visual oddity learning by presentingproblems composed ofthree two-dimensional black-and-white stimuli, two identical (s-) and one different (s+). in the first experimental stage, a single problem per session was presented until learning criterion was reached. in the second experimental stage, all problems were presented only five times in succession; then a new problem was introduced (six problems/session). in the third experimental stage, each problem was pre ... | 2006 | 16933800 |
| contrasting effects of heterozygosity on survival and hookworm resistance in california sea lion pups. | low genetic heterozygosity is associated with loss of fitness in many natural populations. however, it remains unclear whether the mechanism is related to general (i.e. inbreeding) or local effects, in particular from a subset of loci lying close to genes under balancing selection. here we analyse involving heterozygosity-fitness correlations on neonatal survival of california sea lions and on susceptibility to hookworm (uncinaria spp.) infection, the single most important cause of pup mortality ... | 2006 | 16689912 |
| lateralised swimming behaviour in the california sea lion. | lateralised motor behaviour in the pinnipeds has been subject to little investigation. this study examined the swimming behaviour of seven zoo-housed california sea lions to determine whether they exhibited a directional bias in their motor behaviour. data were collected on the direction of the animals' swimming patterns from the point of entering a pool of water from dry land. each animal was studied for 100 episodes of swimming. all seven of the sea lions showed significant (p<0.001) bias in t ... | 2006 | 16682155 |
| mhc gene configuration variation in geographically disparate populations of california sea lions (zalophus californianus). | major histocompatibility complex (mhc) class ii drb genotypes were examined in two geographically isolated populations of california sea lions (zalophus californianus) (gulf of california and california coastal pacific ocean). genomic dna from 227 california sea lions was examined using eight sequence-specific primer (ssp) pairs flanking the putative peptide-binding site. a total of 40 different zaca-drb genotype configurations were identified among the 227 individuals. using ssp-pcr, significan ... | 2006 | 16448418 |
| evaluation of two different biomarkers for use in the assessment of toxic chemical exposure in california sea lions (zalophus californianus). | | 2006 | 16298399 |
| determination of hbcd, pbdes and meo-bdes in california sea lions (zalophus californianus) stranded between 1993 and 2003. | blubber samples from male california sea lions (zalphophus californianus) stranded between 1993 and 2003 were analyzed for 27 polybrominated diphenyl ether (pbde) congeners, three isomers of hexabromocyclododecane (hbcd) and 14 methoxylated polybrominated diphenyl ether (meo-bde) congeners. total pbdes ranged from 450 ng/g to 4740 ng/g wet mass and total hbcd ranged from < 0.3 ng/g to 12 ng/g wet mass. the concentration of hbcd increased from 0.7 ng/g to12.0 ng/g wet mass in sea lion blubber bet ... | 2006 | 16293266 |
| right ear advantage for conspecific calls in adults and subadults, but not infants, california sea lions (zalophus californianus): hemispheric specialization for communication? | this paper explores functional hemispheric asymmetries in the perception of auditory signals in a marine mammal species, the sea lion. using a head-orienting task toward sounds we found a right ear--left hemisphere--advantage for conspecific calls in adult and subadult california sea lions (zalophus californianus) that was absent in infants. non-conspecific sounds did not elicit lateralized reactions in any age group. these findings show that maturational steps regarding communication in the bra ... | 2005 | 15845100 |