摘要:

The sandfish lizard,Scincus scincus(Linnaeus) inhabits the deserts of Africa and the Middle East and spends most of its time buried in the sand. Laboratory experiments have determined that Scincus can respond and orient to insects on the sand surface by detecting vibrations produced by movements of the insects. When buried,Scincuscan detect and respond to crickets and mealworms moving over the surface at distances up to about 15 cm. These responses are guided by vibratory cues, not olfactory cues, as the lizards respond much less frequently to dead insects placed on the surface at equal distances. The lizard obtain directional information from the vibrations, and can localize the insects, orient toward them, and emerge from the sand to capture them.Scincusburied in the sand also respond differently to crickets and mealworms; the faster moving crickets elicit appropriately quicker emergences. Tests with artificial signals have demonstrated that the lizard respond differently to different temporal pattern of seismic signals; fast strike rates, perhaps analogous to fast footstep rates of insect prey, elicit faster emergences. Different velocities of the seismic source also elicit different responses; faster moving sources produce quicker emergences. The lizards therefore are responsive to different aspects of seismic signals that carry certain types of information; in this case,Scincuscan distinguish between different types of prey (slow and fast-moving) and respond appropriately. When walking on the surface of the sand,Scincusoften displays a peculiar behaviour of plunging its head into the sand. Experiments determined that this behaviour aids lizards in detecting vibrations produced by insects moving through the sand, and presumably facilitates transmission of sandborne vibrations to the inner ear.

ISSN:0394-9370    

DOI:10.1080/08927014.1992.9525346

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Site fidelity, initial orientation and homing performance were studied in the natterjack toadBufo calamitanear Bonn, Western Germany, during three breeding periods. Capture-mark-recapture experiments demonstrated that most males stayed within areas of about 0.5 km2during the whole study period. If rainfall provided ephemeral ponds suitable as spawning sites within these areas, local males advertised the position of the ponds by calling. Homeward orientation and homing success of displaced males showed that males were strictly attached to a pond once chosen for several days. The paths of individuals were registered using a mechanical tracking device. However, displaced reproductive females did not return to the breeding pond, if another pond with calling males was less distant from the release site.

ISSN:0394-9370    

DOI:10.1080/08927014.1992.9525347

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The shoreward magnetic compass orientation of male eastern red-spotted newts (Notophthalmus viridescens) was examined in a visually-symmetrical indoor arena. Groups of newts were first trained in a water-filled outdoor tank with an artificial shore at one end and then exposed to a rapid elevation of the training tank water temperature just prior to testing. The directional response of individual newts was observed in the indoor arena in one of four horizontal alignments of the magnetic field (magnetic north at north, east, south or west). Magnetic bearings were pooled from the four magnetic field alignments for analysis. In each test, newts were alternately tested under either 450 nm or 550 nm light (of equal quantal flux) and under full spectrum light. Newts tested under full spectrum light exhibited shoreward magnetic orientation. The distribution of magnetic bearings exhibited by newts under 450 nm light was indistinguishable from that of full spectrum controls. In contrast, the distribution of bearings obtained under 550 nm light differed significantly from controls, exhibiting a shift in orientation of approximately 90° counterclockwise. This wavelength-dependent effect of light on magnetic compass orientation in newts is consistent with the proposed involvement of the visual system in magnetoreception.

ISSN:0394-9370    

DOI:10.1080/08927014.1992.9525348

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

All navigating organisms face similar constraints in terms of the environmental cues that are potentially available to them and the permanence of these cues over evolutionary time. Because these limits are imposed on all organisms, one might expect analogues to occur in the types of cues and orientation strategies used, and in the ontogenetic development of navigational skills among various taxa. Some birds, alligators, turtles, toads and salamanders have been shown to navigate, that is to return to the origin of a displacement in the absence of familiar landmarks or goalemanating cues. Recent work on alligators and homing pigeons illustrates striking parallels between bird and reptile navigational development. In the youngest individuals of both groups the map step of navigation (determination of geographic position) seems to be solved by route-based navigation (continuous position monitoring). Once a local map has been established by repeated exploratory forays, older birds and alligators apparently become capable of extrapolating this map to unfamiliar sites using large scale environmental gradients. The sensory mechanisms used for both the map and compass components of homing are strikingly similar in the amphibians, reptiles and birds. Both celestial and magnetic compasses are well established in all three groups. Although the sensory basis of the navigational map has not been unequivocally established for any group, both magnetic and olfactory cues have been implicated in amphibians, reptiles and birds. These similarities suggest that common mechanisms may underlie true navigation in a variety of vertebrate groups.

ISSN:0394-9370    

DOI:10.1080/08927014.1992.9525349

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The state of our knowledge of wave analysis with the lateral line system in amphibians is reviewed. Knowledge is based largely on tests with the clawed frog,Xenopus laevis, and a few comparative studies in other species. InXenopus, all lateral line organs have equal frequency tuning with maximal sensitivity at 25 Hz. Wave amplitude is encoded over 80 dB by synchronization and mean firing rate. Frequency discrimination has been demonstrated by conditioning, optimal discrimination is 4% at 14 Hz. Wave localization for all directions is very accurate, it depends on comparison of the inputs from neighbouring organs. Comparison between a few organs suffices for accurate localization, these may be located on various parts of the body or may even be unilateral. Centrally, a topological organization with regard to wave direction exists in the mid-brain.Xenopuscan identify and localize component waves in a superposition of waves.

ISSN:0394-9370    

DOI:10.1080/08927014.1992.9525350

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Fire-bellied toads of the genusBombinabelong to those anuran species which call consistently during the mating season. Unlike most other species they generate their calls via an inspiratory airstream. In response to conspecific calls males utter advertisement calls themselves. In order to avoid acoustic overlap, they try to place their calls into silent intervals between the calls of a conspecific male, which, in turn, leads to antiphonal calling. Vocal response and antiphonal calling are controlled by two different inputs from the auditory into the vocal pathway. The two inputs can be distinguished by their filter bandwidth, intensity characteristics, and the latencies between the onset of the response. Comparative behavioural and electromyographic studies reveal that the inhibition of call generation takes place with a delay of ca 60-80 msec after the onset of an auditory signal. Neuroanatomical investigations of the auditory and the vocal pathway by means of the HRP-technique reveal the anatomical basis for audio-vocal interactions at different levels of the toad's brain.

ISSN:0394-9370    

DOI:10.1080/08927014.1992.9525351

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Vertebrate reproduction requires the coordinated expression of somatomotor behavior and visceral responses. Acoustic communication signals and circulating gonadal steroids are two important cues used by anuran amphibians to prime and trigger reproductive behavior. An examination of central nervous system auditory pathways and the binding sites for gonadal steroids shows that somatomotor (striatum) and visceromotor (preoptic area and ventral hypothalamus) control regions of the forebrain each receive an independent, parallel input from auditory relay nuclei in the thalamus, and each contains receptors for gonadal steroid hormones. This suggests that the different aspects of anuran reproductive behavior are coordinated by having the different areas responsible for each aspect concurrently primed by circulating gonadal steroids and simultaneously provided with information regarding the presence of conspecific acoustic communication signals.

ISSN:0394-9370    

DOI:10.1080/08927014.1992.9525352

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The lacertilian parietal eye is a highly organized photoreceptive organ found on the dorsal midline of the head. Developmentally, it is related to the pineal gland but structurally, it resembles the retina of the eye. In contrast to the retina, the parietal eye has a reduced number of components. The photoreceptors synapse directly onto the ganglion cells and there is no convincing evidence of interneurons between these cell types. Retrograde transport studies have revealed two populations of ganglion cells, one in the ganglion cell layer and the other a population of «displaced» ganglion cells located in the photoreceptor layer. The pars dorsolateralis of the left medial habenular nucleus is specialized to receive the projection of the parietal eye ganglion cells. A few centrifugal neurons project to the parietal eye and affect its photoresponsiveness. These centrifugal neurons are stimulated differentially by norepinephrine and serotonin.

ISSN:0394-9370    

DOI:10.1080/08927014.1992.9525353

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Frogs possess a wide binocular visual field which projects retinotopically on both optic lobes through (i) a direct contralateral retinotectal pathway; and through (ii) a bisynaptic ipsilateral visuotectal route. Receptive field properties as well as quantitative relationships between the evoked neuronal activity (mean impulse frequency) and the main characteristics (velocity and size) of a stimulus were successively studied, both in the afferent units and in the binocular cells recorded at single tectal loci. Two broad functional types of visual units were clearly defined, each having specific parameters for their velocity and area functions: (i) a «sustained, tonic» type (R1-R2, II); and (ii) an «event, phasic» type (R3-R3L, 12). Out of the six classes of binocular tectal cells, only a few TIB neurons were studied quantitatively. A similar dichotomy was observed in this neuronal class. The existence of two basic afferent channels in the frog's binocular visual system is discussed.

ISSN:0394-9370    

DOI:10.1080/08927014.1992.9525354

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0394-9370    

DOI:10.1080/08927014.1992.9525345

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor