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At least 19 recordsLinked to original sources

PubMed1989

Comparative milk composition of the bottlenosed dolphin (Tursiops truncatus), humpback dolphin (Sousa plumbea) and common dolphin (Delphinus delphis) from southern African waters.

1. Gross compositional data for milk samples of Tursiops truncatus, Sousa plumbea and Delphinus delphis are presented and compared with existing cetacean milk values. 2. Two factors appear to govern fat content and calorific value of the milk: (a) habitat, and (b) the stage of lactation. 3. Delphinus milk is unusual in that it has a higher P than Ca content. 4. The Fe content in cetacean milk is higher than that for terrestrial mammals and may be related to improved O2 binding requirements.

Africa, Southern↗

PubMed1976

[Features of the structural organization of the dolphin (Phocaena phocaena) lateral geniculate body in comparison to other dolphins].

The work describes a new for dolphins type of the cytoarchitectonic organization and topographo-anatomical features of the dorsal nucleus of the external geniculate body found in the dolphin Phocaena phocaena. In dolphins only the alveolar type of organization of the formation in question had been known which was principally different from the laminar and nuclear types characteristic of the terrestrial mammals. The Phocaena phocaena proved to have the nuclear type of organization of the external geniculate body, as well as in certain mammals. In addition, a fact of a sharp quantitative diminution of the external geniculate body as compared with other dolphins has been revealed which is of interest for the physiology of vision. This fact is of significance showing the total amount of nerve cells in the dorsal nucleus of the external geniculate body of the Phocaena phocaena to be equal to 6,6% as compared with the white-sided dolphin. Since the above diminution proved to be selective and did not take place in the anterior tuber of the quadrigeminum, the author puts forward the idea that a considerably less afferentation comes to the visual cortex of the Phocaena phocaena than to that of other dolphins, due to some, yet unknown, restriction of the visual function.

Animals↗

PubMed1976

Staphylococcus aureus infections of captive dolphins (Tursiops truncatus) and oceanarium personnel.

Samples from blowhole and pharynx of 1 dolphin ill with a respiratory tract infection and 31 healthy dolphins at 2 oceanariums were examined by bacteriologic cultural technique. During the same period, nasal and volar forearm skin samples were collected from 32 healthy personnel and from a furuncle on the forearm of 1 attendant. Coagulase-positive staphylococci were isolated from 8 dolphins (including the ill dolphin) and from 14 persons. Antibiotic sensitivity patterns (8 drugs were tested) differed markedly for the staphylococcal isolates recovered from dolphins, as compared with those from persons. Staphylocci from the dolphins were totally or partially sensitive to every antibiotic, whereas almost all of the isolates from persons were resistant to penicillin and ampicillin, as well as to certain other antibiotics. Staphylococcus bacteriophage typing revealed that only 1 isolate from a dolphin could be typed (type D11). Six of the isolates from persons were typable, but no isolate was sensitive to only type D11. It was concluded that, although Staphylococcus aureus could be isolated commonly from captive dolphins, there was no evidence of cross infection between the dolphins and the oceanarium personnel.

Animals↗

PubMed1992

Calretinin-immunoreactive neurons in the primary visual cortex of dolphin and human brains.

A new class of gamma-aminobutyric acid (GABA)ergic neurons immunoreactive to the calcium-binding protein calretinin (CR) was demonstrated in primary visual cortices of the bottlenose dolphin (Tursiops truncatus) and humans (Homo sapiens). Comparative analysis revealed several differences between dolphin and human visual cortex in the laminar distribution of CR-positive perikarya, although general typology of the immunoreactive CR-positive neurons was similar in both species. Thus, in both human and dolphin primary visual cortex almost all CR-positive neurons are non-pyramidal, either fusiform or bipolar cells, oriented with their long axis along the radial axis of the cortex. Large multipolar stellate cells were also observed in layers I and VI. The CR-positive neurons in the dolphin visual cortex are concentrated almost exclusively in layer I and, to a lesser extent, in layer II. In all other layers (IIIa, b, IIIc/V and VI) of the dolphin visual cortex CR-positive neurons were only rarely seen. In the human primary visual cortex CR-positive neurons are located mainly in layers II, III and IVa, b, c, with considerably lower densities of these cells observed in layers V and VI. CR-positive neurons in layer I of the human visual cortex are represented by Cajal-Retzius horizontal cells, whereas no such cells were seen in layer I of the dolphin neocortex. The numerical density of CR-positive neurons in the dolphin primary visual cortex is significantly lower than in the area of cortex in humans.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1985

Reporting presence or absence of named objects by a language-trained dolphin.

Referential "reporting" was defined as the transmission of information about the presence or absence of symbolically-referenced real-world objects. In Experiment 1 two bottlenosed dolphins (Tursiops truncatus), trained in earlier studies to carry out instructions conveyed by imperative sentences expressed in artificial gestural or acoustic languages, each gave spontaneous indications that an object referenced in an imperative was absent from their tank. In Experiment 2 the dolphin tutored in the gestural language was taught to make explicit reports of object absence by pressing a "No" paddle in response to imperatives referencing an absent object. Absence was reported correctly on 84% of 97 missing-object probes inserted at random intervals among 598 sentences referring to objects that were present. Reports were typically made after active search of the tank for an average of 15.0 sec. False reports, that objects present were absent, were few (7.5%). In Experiment 3, the dolphin was taught an interrogative sentence form that enabled us to ask direct questions about the presence or absence of specific objects. Responses by the dolphin on the No paddle indicated absence, while responses on a "Yes" paddle indicated presence. From one to three objects were shown the dolphin and then placed in the tank in a discrete-trial procedure. In response to the interrogative, reports or object presence or absence were better than 91% correct with a single object in the tank and either that object or some other object referenced; accuracy declined to 72-78% correct with three objects present, but was still well above chance. Several lines of evidence suggested that the dolphin was attempting to remember which objects it had been shown, rather than conducting an active environmental search as in Experiment 2. The memory strategy became less efficient as the number of objects to be remembered increased. Overall, the results evidenced the language-trained dolphin's understanding of references to present or absent objects, its ability to inventory its environment to seek information about those objects, and its ability to report its obtained knowledge to others.

Animal Communication↗

PubMed1992

Pathologic and immunocytochemical studies of morbillivirus infection in striped dolphins (Stenella coeruleoalba).

Hundreds of striped dolphins (Stenella coeruleoalba) died along the Spanish Mediterranean coast during the second half of 1990. We necropsied 58 dolphins. Partial collapse of the lungs with patchy atelectasis, subcutaneous edema, icterus, and stomatitis were the most prominent gross morphologic changes. Histologically, a bronchiolo-interstitial pneumonia was the most frequent lesion (72% of the animals). It was characterized by hyperplasia of alveolar epithelial type II cells and formation of multinucleate syncytia in alveolar and bronchiolar lumina. Other prominent lesions were encephalitis (69%), lymphoid depletion, and formation of multinucleate syncytia in the cortex of lymph nodes. The distribution of morbillivirus antigen was investigated in 23 well-preserved dolphins using a monoclonal antibody against the hemagglutinin glycoprotein of phocine distemper virus. Positive immunostaining was found in brain (77%), in lung (70%), and in mesenteric (61%), mediastinal (47%), and prescapular (45%) lymph nodes. Phocine distemper virus antigen was demonstrated less frequently in trachea, stomach, biliary epithelium, intestine, kidney, and mammary gland. Necrotizing-hemorrhagic pneumonia and encephalitis due to Aspergillus fumigatus were seen in three dolphins, whereas two animals had lesions of toxoplasmosis. Changes in our dolphins were similar to those caused by distemper in seals and porpoises. The origin of the dolphin virus and the relationships among dolphin, seal, and porpoise morbilli viruses are unknown.

Animals↗

PubMed1989

A comparison of signal detection between an echolocating dolphin and an optimal receiver.

An electronic simulated target apparatus was used in a two-experiment study to compare the target detection performance of an echolocating bottlenose dolphin with an optimal receiver. Random Gaussian noise with a relatively flat spectrum from 20 to 160 kHz was used as a masking source. Experiment I was conducted to establish a technique for estimating the echo energy-to-noise ratio, Ee/N, at the dolphin's threshold of detection. Dolphins typically vary the amplitude of their emitted signal over a large range making it difficult to estimate Ee/N. In the first part of experiment I, the simulated echo was a double click, the pulses separated by 200 microseconds, with each pulse being a replica of the dolphin's transmitted signal. A staircase psychophysical procedure was used to obtain the detection threshold, and the echo energy-to-noise ratio based on the highest amplitude click emitted per trial, (Ee/N)max, was determined at each reversal point. The second echo type consisted of one of the animal's echolocation clicks, previously measured, digitized and stored in an erasable programmable read-only memory (EPROM). The electronic target simulator was modified so that every time the dolphin emitted an echolocation signal, the EPROM was triggered to produce two pulses separated by 200 microseconds. On any trial, the EPROM signal was played back at a fixed amplitude, regardless of the amplitude of the dolphin's emitted signal. The Ee/N obtained with the EPROM signal at threshold was found to be 2.9 dB lower than (Ee/N)max obtained with the normal phantom target. Therefore an estimate of Ee/N can be obtained by subtracting 2.9 dB from (Ee/N)max.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Bottlenosed dolphin and human recognition of veridical and degraded video displays of an artificial gestural language.

2 bottlenosed dolphins proficient in interpreting gesture language signs viewed veridical and degraded gestures via TV without explicit training. In Exp. 1, dolphins immediately understood most gestures: Performance was high throughout degradations successively obscuring the head, torso, arms, and fingers, though deficits occurred for gestures degraded to a point-light display (PLD) of the signer's hands. In Exp. 2, humans of varying gestural fluency saw the PLD and veridical gestures from Exp. 1. Again, performance declined in the PLD condition. Though the dolphin recognized gestures as accurately as fluent humans, effects of the gesture's formational properties were not identical for humans and dolphin. Results suggest that the dolphin uses a network of semantic and gestural representations, that bottom-up processing predominates when the dolphin's short-term memory is taxed, and that recognition is affected by variables germane to grammatical category, short-term memory, and visual perception.

Animal Communication↗

PubMed1992

Travel at low energetic cost by swimming and wave-riding bottlenose dolphins.

Over the past 50 years there has been much speculation about the energetic cost of swimming and wave-riding by dolphins. When aligned properly in front of the bow of moving ships in the stern wake of small boats, on wind waves, and even in the wake of larger cetaceans, the animals appear to move effortlessly through the water without the benefit of propulsive strokes by the flukes. Theoretically, body streamlining as well as other anatomical and behavioural adaptations contribute to low transport costs in these animals. The economy of movement permitted by wave-riding has been perceived as an energetic advantage for the swimming dolphin, but has been hard to prove in the absence of physiological data for exercising cetaceans. Here we determine the aerobic and anaerobic costs of swimming and wave-riding in bottlenose dolphins and find that the minimum cost of transport for swimming dolphins is 1.29 +/- 0.05 J kg-1 m-1 at a cruising speed of 2.1 m s-1. Aerobic costs are nearly twice as high for swimming seals and sea lions, and 8-12 times higher for human swimmers. Wave-riding by dolphins provides additional benefits in terms of speed. The results indicate that behavioural, physiological and morphological factors make swimming an economical form of high-speed travel for dolphins.

Animals↗

PubMed1988

Detection of complex echoes in noise by an echolocating dolphin.

Dolphins echolocate with short broadband acoustic signals that have good time resolution properties. Received echoes are often complex, with many resolvable highlights or components caused by reflection of the incident signal from external and internal boundaries of a target and from different propagational modes within a target. A series of experiments was performed to investigate how dolphins perceive complex echoes. Echoes were produced by a microprocessor-controlled electronic target simulator that captured each emitted click and retransmitted the signal back to the animal after an appropriate time delay. The use of this "phantom" target allowed for precise control of the number of highlights, the time separation between highlights, and the relative amplitudes of highlights in the simulated echoes. An echolocating dolphin was trained to perform a target detection task in the presence of masking noise using these phantom echoes. The properties of simulated echoes were systematically varied, and corresponding shifts in the dolphin's detection threshold were observed, allowing for inferences of how the dolphin perceived echoes. The dolphin performed like an energy detector with an integration time of approximately 264 microseconds.

Acoustic Stimulation↗

PubMedDate not supplied

Molecular characterization of a cloned dolphin mitochondrial genome.

DNA clones have been isolated that span the complete mitochondrial (mt) genome of the dolphin, Cephalorhynchus commersonii. Hybridization experiments with purified primate mtDNA probes have established that there is close resemblance in the general organization of the dolphin mt genome and the terrestrial mammalian mt genomes. Sequences covering 2381 bp of the dolphin mt genome from the major noncoding region, three tRNA genes, and parts of the genes encoding cytochrome b, NADH dehydrogenase subunit 3 (ND3), and 16S rRNA have been compared with corresponding regions from other mammalian genomes. There is a general tendency throughout the sequenced regions for greater similarity between dolphin and bovine mt genomes than between dolphin and rodent or human mt genomes.

Animals↗

PubMed1987

Ultrastructure of the blood-brain barrier in the dolphin (Stenella coeruleoalba).

Light and electron microscopic methods were used for investigation of angioarchitectonics, glioarchitectonics and the structural basis of the blood-brain barrier in the dolphin Stenella coeruleoalba. It was shown that the cortical plate of the dolphin brain is extremely rich in capillaries and small arteries that are organized into a complicated net of continuous loops surrounding neuronal groups. The density of the capillary loops is related to the cytoarchitectural density of the cortex. It was also found that the neuronal microenvironment in the dolphin cortex is characterized by the presence of a large number of the astroglia-like cells that make a multi-layered investment surrounding capillaries and small arteries. These glial cells, unlike typical astrocytes of terrestrial mammals, have a large number of different organelles and their nuclei are similar to those of the oligocytes. The ultrastructure of the blood-brain barrier in the dolphin is characterized by the presence of extremely long tight junctions between endothelial cells and by specialized junctions between pericapillary astroglia-like cells. A belt of the glial end-feet interlocked with different types of junctions such as zonulae adherentes, maculae adherentes and gap junctions was found around all investigated capillaries. This system of specialized interendothelial and glio-glial junctions is tentatively hypothesized to be a feature of adaptation of the dolphin to the aquatic environment.

Animals↗

PubMed1989

Insights into dolphin sonar discrimination capabilities from human listening experiments.

A variety of dolphin sonar discrimination experiments have been conducted, yet little is known about the cues utilized by dolphins in making fine target discriminations. In order to gain insights on cues available to echolocating dolphins, sonar discrimination experiments were conducted with human subjects using the same targets employed in dolphin experiments. When digital recordings of echoes from targets ensonified with a dolphinlike signal were played back at a slower rate to human subjects, they could also make fine target discriminations under controlled laboratory conditions about as well as dolphins under less controlled conditions. Subjects reported that time-separation-pitch and duration cues were important. They also reported that low-amplitude echo components 32 dB below the maximum echo component were usable. The signal-to-noise ratio had to be greater than 10 dB above the detection threshold for simple discrimination and 30 dB for difficult discrimination. Except for two cases in which spectral cues in the form of "click pitch" were important, subjects indicated that time-domain rather than frequency-domain processing seemed to be more relevant in analyzing the echoes.

Animals↗

PubMed1991

A datalogger to identify vocalizing dolphins.

A datalogger was developed to identify vocalizing dolphins within socially interacting captive groups. Every 50 ms the logger stores data on the level and frequency of detected sound. Dataloggers are temporarily attached to dolphins by suction cups for data collection sessions lasting up to 45 min. Later, computer analysis of data from the dataloggers reveals which dolphin produced each vocalization recorded during the session. Results from use of dataloggers with two captive bottlenose dolphins (Tursiops truncatus) at the New England Aquarium in Boston, MA are presented. The possible use of dataloggers with wild dolphins is discussed.

Animals↗

PubMed1992

Mass stranding of striped dolphin, Stenella coeruleoalba, at Augusta, Western Australia: notes on clinical pathology and general observations.

Seventeen striped dolphins, Stenella coeruleoalba, were found stranded on a West Australian beach. Three animals died before a rescue attempt was made and a further three died during the rescue. The remaining dolphins were released 24 km offshore and were not seen again. One dolphin was noted to have a broken mandible. Evidence of physical trauma to the other dolphins was minimal; one adult female was observed with some peeling skin. Blood was collected for analysis. All dolphins were slightly dehydrated and had a leukogram typical of a stressed animal. Plasma biochemistry reflected primary muscle trauma. There were no clues to the cause of the stranding; observed pathology reflected damage that occurred as a direct consequence of stranding.

Animals↗

PubMed1975

[Cytoarchitecture of the formatio reticularis of the brain stem of the dolphin].

In the present study some qualitative and quantitative features of the reticular formation of the medulla oblongata, pons and midbrain have been elucidated by cytoarchitectonic methods in the dolphin (Tursiops truncatus). The studies have demonstrated that similar to land mammalia, the dolphin has a reticular formation made up of spatially open cell groups lying in the deepest parts of the brain stem. Cytoarchitectonically the component parts of the reticular formation show a number of peculiarities enabling us to distinguish separate nuclei. In the dolphin peculiar architectonics have been observed in the nucleus gigantocellularis medullae oblongatae, nucleus papillioformis or the nucleus reticularis tegmenti Bechterewi and the nucleus centralis superior medialis seu ventralis. Fairly poor in cells are the nucleus centralis caudalis pontis and the nucleus centralis oralis pontis. We failed to single out as autonomous nuclei cell groups corresponding to the nucleus funiculi lateralis and the nucleus paratrochlearis of the land mammalia. The size and density of cells in nuclei have a number of peculiarities. The analysis of the ratios of the brainstem volume to that of reticular structures has shown them to be the smallest in the dolphin as compared with land mammals. The smaller share held by the brain-stem reticular formation and its cytoarchitectonic features can be associated with the functional properties resulting from the greater specialization of some of brain-stem systems (e.g. auditory, vestibular, extrapyramidal etc.) in the dolphin in comparison with land mammals.

Animals↗

PubMed1992

Pathology of morbillivirus infection in striped dolphins (Stenella coeruleoalba) from Valencia and Murcia, Spain.

During the summer and fall of 1990 hundreds of striped dolphins (Stenella coeruleoalba) died in the Spanish Mediterranean as a result of morbillivirus infection. A pathological investigation was carried out on dolphins from Valencia and Murcia which were among the first to die in the epizootic. The dolphins were in poor body condition and pneumonia was the main necropsy finding. Microscopic lung lesions characterized by necrosis of bronchial and bronchiolar epithelium and infiltration of alveoli with macrophages, lymphocytes, neutrophils and multinucleated syncytia were seen in most dolphins. Cytoplasmic and nuclear eosinophilic viral inclusions were present in bronchial and bronchiolar epithelium and in syncytia. Focal granulomatous inflammation associated with nematodes was also present. Brain lesions included diffuse degeneration and necrosis of neurons, microgliosis, perivascular cuffing, formation of syncytia and focal demyelination. Cytoplasmic and nuclear eosinophilic inclusions were present in neurons and glial cells. There was severe lymphoid necrosis and depletion of spleen and lymph nodes and syncytia also occurred in lymph nodes. Biliary and transitional epithelium contained nuclear and cytoplasmic eosinophilic inclusions. Immunoperoxidase staining using monoclonal antibodies to phocine distemper virus confirmed the presence of morbillivirus antigens in lung and brain. The distribution and severity of lesions in striped dolphins are similar to those of distemper in seals, harbor porpoises and terrestrial mammals. The formation of syncytia in the lung and brain may be a useful pathological indicator of morbillivirus infection and may be used in the investigation of pinniped and cetacean strandings in North America.

Animals↗

PubMed1988

Visual cortex of the dolphin: an image analysis study.

On cytoarchitectonic grounds we have identified two distinct types of cortical formations composing the lateral gyrus (visual cortex) of the dolphin and have termed these heterolaminar cortex and homolaminar cortex. The heterolaminar cortex occupies the medial and lateral banks of the entolateral sulcus whereas the homolaminar cortex occupies the remainder of the lateral gyrus both lateral and medial to the entolateral sulcus. Each of these cortices exhibits special cytoarchitectonic features, a major difference being that heterolaminar cortex contains an incipient layer IV whereas layer IV is clearly absent in homolaminar cortex. Quantitative imaging procedures reveal that there is greater laminar differentiation in heterolaminar than in homolaminar cortex. Golgi analysis of neuronal forms and dendritic architecture confirms this distinction between the two types of cortex composing the lateral gyrus. Computer-assisted morphometric methods have been applied to both types of cortex and indicate by a variety of parameters several quantitative differences in the cellular numbers, types, and organization in each type of cortex. Both types of cortex, homolaminar and heterolaminar, exhibit a markedly higher cellular density in the posterior sector of the lateral gyrus than in the anterior sector. We have also for the first time been able to identify a columnar type of organization of the cetacean visual cortex and have described two types of cytoarchitectonic columns, major and minor, in each of these types of cortex. Comparisons in organization of these basic columnar units between the bat, representing a prototypic brain, and the dolphin reveal many similarities but also major quantitative differences in type of organization between the visual cortices in these species. Marked differences are also seen between the cytoarchitectonic columnar organization of the visual cortices in the dolphin and columnar organization of striate cortex in the human brain, the number of columns per unit of cortex in the human being almost twice that seen in the dolphin brain. Some phylogenetic implications of these findings are discussed in relation to the so-called "initial" type of cortical organization reconstructed largely by retrospective inference.

Aging↗