Showing papers in "Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology in 1972"

Zur spektralen Unterschiedsempfindlichkeit der Honigbiene

Abstract: 1. Die im Dressurexperiment gemessene spektrale Empfindlichkeitskurve der Honigbiene ist dreigipfelig, was die Ergebnisse von Thomas und Autrum (1965) bestatigt. Die Maxima liegen etwa bei den Wellenlangen 345 nm (Ultraviolett), 440 nm (Blau) und 550 nm (Gelbgrun), vgl. Abb. 11. 2. Die Kurve der spektralen Unterschiedsempfindlichkeit der Biene weist zwei Optima auf, die etwa bei den Wellenlangen 400 nm (Violett) und 500 nm (Blaugrun) liegen (Abb. 18, 19). Im empfindlichsten Bereich des Unterscheidungsvermogens, im Blaugrun, wurden unter den gegebenen Versuchsbedingungen von der Biene noch Wellenlangen-Differenzen von 4,5 nm mit einer Anflughaufigkeit von 70% unterschieden. Der spektrale Verlauf der Parbton-Unterscheidung last sich am besten unter der Annahme eines trichromatischen Farbsystems verstehen, insbesondere zeigen die Ergebnisse, das das farbauswertende System der Biene die Daten nur eines Blaurezeptor-Typs verwendet.

A behavioural analysis of the temporal organisation of walking movements in the 1st instar and adult stick insect ( Carausius morosus )

Abstract: The coordination of protraction leg movements in free walking first instar and adult stick insects has been examined by film and video-tape analysis. The first instar insect uses two alternative modes of walking which differ in the step frequency dependence of the time required to complete one metachronal cycle of protractions and the duration of the protraction cycle (Figs. 2, 4). The adult uses only one of these modes and its step patterns show a persistent right-left asymmetry in the timing of leg movements (Fig. 7). Two alternative methods of changing direction were found (Figs. 5, 9) and they appear to be related to the two modes of walking used by the animal. A model based on inhibitory interactions between oscillators representing leg activity has been constructed to explain the step pattern changes in both modes of walking and the temporal asymmetry of the adult pattern. This model appears to be applicable to the walking behaviour of other insects including the cockroach.

The jamming avoidance response of high frequency electric fish: I. General features

Abstract: Summary1.The J.A.R. is a reflex shift in the frequency of discharge of their electric organs by high frequency electric fish (Gymnotidae:Eigenmannia, Sternarchus) when stimulated by an alternating current in the water, with a frequency close to the fish's. The shift is in the direction of increasing the difference (ΔF) between its frequency (Ffish) and that of the stimulus (Fstim). The significance of this behavior is presumed to be the maintenance of a private frequency for the object-detection function of the electric system, when another fish of nearly the same frequency approaches.2.The pathway (Fig. 1) includes a high precision pacemaker unit in the medulla under the tonic influence of electroreceptors. The simplicity of the relevant parameters and the convergence on one command unit in a complete piece of quantifiable social behavior attracts attention to the J.A.R.3.The latency, time course, form, asymmetry, and variability, the effects of temperature, anesthesia, mechanical and electrical disturbance, light, salinity and spontaneous background changes, and the absence of effect of sound are described (Figs. 2, 3, 4, 5).4.Eigenmannia will usually shiftFfish up for a — ΔF and down for a +ΔF, rather symmetrically;Sternarchus will only shift upwards and gives no response to a +ΔF.5.Experimentally isolating parts of the system indicates that the fish does not compare the stimulus frequency with its pacemaker frequency directly but must receive both through the same set of electroreceptors.6.The stimuli of opposite effect, when given simultaneously cause an intermediate response, i.e. both stimuli are effective.7.The response survives section of the posterior branch of the anterior lateral line nerves bilaterally and, with slightly raised threshold and latency, of the supraorbital and maxillary branches as well, leaving only the mandibular. It survives partial lesions of the corpus cerebelli and valvula and complete transection in front of the mesencephalon. Lesions of the torus semicircularis of the mesencephalon cause loss or gross abnormality of the J.A.R.8.The ΔF sensitivity, dynamic range and other properties suggest that the biological significance of preserving a private frequency lies in the need of unknown brain mechanisms, that analyze the fish's own field for object detection, to function over a considerable range of distance from object to fish and therefore of voltage of a signal clearly the fish's own.9.Evidence from bringing two or more fish together, whose separate frequencies are close, suggests the J.A.R. is used in natural social situations.

Anaerobic metabolism during activity in lizards

Abstract: A new technique developed for the determination of total lactate production in small animals was used to evaluate the role of anaerobiosis during activity at different temperatures in lizards. Measurements on six species of small lizards indicate little interspecific variation or thermal effect in resting lactate levels (0.35 mg lactate/g body weight) or maximal lactate levels achieved at exhaustion (1.4 mg lactate/g). Normally activeAnolis in captivity had a lactate content of 0.5 mg lactate/g. Rates of lactate formation were most rapid during the first 30 sec of activity and had a low thermal dependence (Q10=1.1–1.3 above 20 °C). The lactate formed during activity persists for long periods; e.g., for 30 to 60 min between 20 and 37 °C inAnolis carolinensis (Fig. 1). Recovery rate generally increases with temperature. Muscle lactate concentrations peak at the end of activity, but liver and blood lactate are not maximal until 10 and 30 min, respectively, after activity (Fig. 2). The decrease in the blood lactate is shown to be a poor estimator of total recovery. An estimated 80–90% of the total energy utilized during initial vigorous activity comes from anaerobic sources. Because of its low thermal dependence, anaerobiosis permits high levels of activity in lizards at all body temperatures without requiring high levels of aerobic resting metabolism.

Gesang des Männchens und Lautschema des Weibchens bei der FeldheuschreckeChorthippus biguttulus (Orthoptera, Acrididae)

Abstract: 1. Der Gesang der FeldheuschreckeChorthippus biguttulus ist ein charakteristisch amplitudenmoduliertes Lautmuster (Abb. 2): Der Spontangesang besteht aus 1–5 (meist 3) Versen und jeder Vers aus 20–60 Silben (u.a. Faber, 1929). Die Silben sind ihrerseits aus Pulsen aufgebaut, was besonders im Gesang einseitig amputierter Mannchen deutlich zu erkennen ist, und zwar bis auf seltene Ausnahmen stets aus einer geraden Anzahl. Nach der Zahl der Pulse (4, 6 oder 8, selten auch mehr) kann man verschiedene Silbentypen unterscheiden. Die Silbenund Pausendauern sind bei einer vorgegebenen Temperatur wenig variabel (Abb. 3, 4, 5). Der „Werbewechselgesang” unterscheidet sich im zeitlichen Muster der Silben- und Pausendauern nicht vom Spontangesang. 2. Mit steigender Temperatur verkurzen sich sowohl die Dauern der verschiedenen Silbentypen als auch die Pausendauern nach einer Exponentialfunktion. Das Verhaltnis zwischen Silben- und Pausendauer bleibt dabei konstant (Abb. 6, 7, 8). 3. Das Lautschema (angeborener auslosender Mechanismus des Weibchens fur die Antwort auf den Gesang eines Mannchens) bleibt wahrend der Lebensdauer eines Weibchens konstant. Eine Lautattrappe aus getastetem Rauschen lost nur dann eine Antwort aus, wenn die Parameter Silben- und Pausendauer bestimmte, voneinander abhangige Werte annehmen: Mit steigender Silbendauer wird auch die am besten beantwortete Pause langer (Abb. 14). Tragt man die optimal beantwortete Pausendauer als Funktion der Silbendauer auf, so erhalt man annahernd eine Gerade (Abb. 15). Versdauer, Versabstand und Verszahl spielen beim Erkennen des Artgesanges nur eine untergeordnete Rolle, jedoch mus eine Mindestversdauer von etwa 1,2 s eingehalten werden (Abb. 18). Die Abstande zwischen den Pulsen durfen (unter den gegebenen Versuchsbedingungen) 1–2 ms nicht uberschreiten, soll das Muster seine Wirksamkeit nicht verlieren. Bei langeren Pulsen ist auch die tolerierte Pulspause groser (Abb. 19). 4. Das Lautschema ist temperaturabhangig. Bei niedrigerer Temperatur werden bei einer gegebenen Silbendauer langere Pausen maximal beantwortet und insgesamt langere Silben bevorzugt (Abb. 15, 20). 5. Das Lautschema eines Weibchens umfast bei einer Temperatur von 35 ° C nicht nur die Gesangsmuster von Mannchen derselben Temperatur, sondern die Silben-Pausen-Muster eines weiten Temperaturbereiches (Abb. 17, 21).

Physiology of insect rhythms

Abstract: 1. In silkmoths the gating of adult eclosion by light-dark cycles persists after extirpation of the compound eyes, frontal ganglion, subesophageal ganglion, or corpora allata-corpora cardiaca complex. Removal of the brain abolishes gating and such moths emerge irrespective of time of day or night. 2. Implantation of a brain into the abdomen of a debrained animal restores the ability both to entrain to a light-dark cycle and to free-run under conditions of continuous darkness. 3. Implantation of pieces of brain which contain the cerebral lobes likewise restored to debrained moths the ability to entrain and to free-run. But the synchrony was not as sharp as that observed in moths which had received implants of the entire brain. 4. Transection of the brain lateral to each median neurosecretory cell cluster yields pieces which are apparently incapable of gating the eclosion of debrained moths. Both moths receiving the median piece and those receiving the lateral pieces showed a randomized distribution of eclosion. 5. Experiments involving brain transplantation and selective illumination of parts of the body showed that the brain directly receives the light information which is necessary for the entrainment of the clock. 6. In theCecropia moth, the lights-on signal serves to stimulate eclosion and thus partially masks the output of the clock. This effect is mediated solely by light which is perceived by the compound eyes.

The Jamming Avoidance Response of High Frequency Electric Fish

Abstract: Using a frequency difference (Δ F) clamp to maintain a stimulus and frustrate the normal escape from a jamming frequency, the response is found to be a characteristic function of the ΔF between stimulus and fish (Figs. 2, 3, 4, 6). It is graded on both sides of a best ΔF of about 3 Hz (= 0.3% in Sternarchus, 1.0% in Eigenmannia). There is no systematic response when F stimulus = F fish, regardless of phase.

Basal energy metabolism of mustelids

Abstract: Oxygen consumption was measured during sleep in seven species of mustelids. Their body weight ranged from 50 g to 15 kg. When basal metabolic rate (BMR) was plotted against weight on logarithmic coordinates (Fig. 1), a break in the linearity appeared at a weight level of about one kg. In species with a body weight below one kg, the regression line of BMR against weight is best represented by the equation M = 95.8W0.55 (±0.03; standard error of estimate) where M is basal metabolic rate in kcal/day and W is body weight in kg. The equation M = 84.6 W0.78 (±0.15) describes the relationship of animals weighing one kg or more, indicating that the BMR is proportional to almost the same fractional power of body weight, 0.75, as that of other mammals. The high BMR observed in weasels and stoats, suggests that a metabolic adjustment has occurred in the smaller species of the mustelid family.

The pterostigma of insect wings an inertial regulator of wing pitch

Abstract: 1. The pterostigma of insect wings usually is a pigmented spot close to the leading edge far out on the wing, having a greater mass than an equally large wing piece in adjacent wing regions. 2. In several dragonfly (Odonata) species the position of the spanwise torsion axis of the wings, the mass distribution of the wings, and the position of the chordwise centre of mass in chordwise wing strips were determined. 3. In the dragonflies investigated, the torsion axis of the wing lies ahead of the chordwise centre of mass of the wing except at the pterostigma (Fig. 1). 4. A wing having its mass axis behind its torsion axis is very susceptible to self-excited coupled flapping and feathering vibrations, making gliding flight above a critical speed impossible. Due to unfavourable, inertial, wing pitching tendencies, a still lower speed limit is set to active flight. 5. Due to its mass contribution and favourable location, the pterostigma tends to raise these speed limits by causing favourable, inertial, pitching moments during the acceleration phases of wing flapping. 6. The favourable pitching moment of the pterostigma is proportional to the distance from the wing base to the pterostigma, and to the distance of the pterostigma ahead of the wing's spanwise torsion axis. The pterostigma usually has an optimal position at the leading edge of the wing near the wing tip, just where the wing curves backwards. Further optimization of pterostigma mass localization has been obtained in different ways in various insects, involving both pterostigma position (Fig. 4) and form (Fig. 5a). 7. The function of the pterostigma of raising the critical gliding speed, at which self-excited vibrations set in, was demonstrated in dragonflies. Although contributing only 0.1 % (one pterostigma) of the total dragonfly weight, it raised the critical speed by 10–25% in one species. 8. The pterostigma is common among the insect orders Odonata, Neuroptera, Psocoptera, Hemiptera, and Hymenoptera. By passive, inertial, pitch angle control, the pterostigma probably makes the wing beat more efficient in slow and hovering flight of small insects, while its raising of the critical flight speeds probably is of more importance to larger insects. The ability of active pitch angle control in many insects does not detract from the value of the pterostigma, since it contributes passively, without power expenditure, towards an efficient wing stroke.

Circadian control of stridulation in the cricketTeleogryllus commodus Walker

Abstract: 1. The cricketTeleogryllus commodus Walk, has a circadian stridulatory rhythm, whose free-running period is 25 h 40' in LL at 20–35 Lux light intensity, and 23 h 36' in DD. Under LD conditions, stridulatory activity is synchronized and begins 2 h before the onset of darkness. 2. The compound eyes are the only photoreceptors through which entrainment by environmental light-dark changes can take place. Uncoupling of the compound eyes from the environment by cutting the ommatidial nerves results under LD or LL conditions in a free-running stridulatory rhythm similar to that of unoperated ♂♂ held in DD. 3. Severance of both optic lobes causes a breakdown of the singing-rhythm and stridulation is randomly distributed over the 24 h-period. Removal of one optic lobe does not affect the rhythm. The location of the timing-device is discussed with regard to these results.

Nervous control of walking in the crab, Cardisoma guanhumi

Abstract: 1. Discharge patterns in the motoneurons innervating the propodite stretcher and bender muscles and dactylopodite opener and closer muscles of the legs of the land crab, Cardisoma guanhumi, were recorded during sideways walking on a styrofoam wheel (Fig. 1). 2. Rhythmic bursts of activity in these motoneurons can be correlated with leg movements during walking in both leading and trailing legs (Figs. 2, 3A, B, D). Similar patterns of activity can be recorded in animals freely walking on a bench (Fig. 3C). 3. These motor output patterns are quite different from those occurring in the same motoneurons during resistance reflexes. In particular, the shared openerstretcher excitor and the stretcher inhibitor show no preferential phase relationship during walking (Figs. 4, 5). It appears that the normal movements of the propo-dactylopodite (P-D) joint during walking do not give rise to resistance reflexes. 4. Opening and closing movements of the P-D joint, manually imposed during walking, induce resistance reflexes (Figs. 6, 7). Reflexes tend to be stronger, both in terms of number of impulses and impulse frequency, when the imposed movement opposes rather than reinforces ongoing P-D movements. 5. Animals walking sideways on the wheel with the P-D joint clamped rigidly in a stable position show only slight changes in their motor output patterns from those seen during normal walking (Fig. 3E). 6. A model is discussed in which the proprioceptive input resulting from the normal movements of the P-D joint during walking is inhibited centrally and so does not give rise to a resistance reflex. 7. These results clearly indicate that resistance reflexes do not play an important role in coordination of antagonistic muscles during walking. Instead it is likely that their primary function is to compensate for changes in the load applied at a joint as would occur on steep inclines and irregular surfaces.

The effect of activity on oxygen consumption, oxygen debt, and heart rate in the lizards Varanus gouldii and sauromalus hispidus

Abstract: Oxygen consumption and heart rate were measured during rest and activity in the lizardsVaranus gouldii andSauromalus hispidus. Oxygen debt was calculated from postactive oxygen consumption. Standard metabolic rates of the two animals are similar butVaranus consumes much more oxygen during activity than doesSauromalus (Fig. 1–3). The latter has a constant active metabolic rate above 30 ° C and accumulates a large oxygen debt, which is repayed slowly (Fig. 4).Varanus recovers rapidly from activity (Fig. 5), presumably because of the smaller lactacid debt incurred. Heart rate increment inSauromalus is high (Fig. 8). This variable cannot be responsible for the limitation of active oxygen consumption; calculations of oxygen pulse suggest that an inability to increase A-V difference and/or stroke volume are implicated (Fig. 9).Varanus have evolved mechanisms to sustain high levels of oxygen consumption superior to those of other reptiles investigated. The role of anaerobiosis in the biology of both animals is discussed.

Energetics of temperature regulation and foraging in a bumblebee, Bombus terricola kirby

Abstract: Temperature regulation inBombus terricola was investigated in the field in relation to foraging energetics on flowers differing widely in morphology and nectar contents. 1. While foraging for nectar fromAsclepias syriaca mean thoracic temperature (TTh) was relatively independent from ambient thermal conditions, ranging from 35.2 °C in shade at 12 °C, to 37.5 °C in sunshine at 28 °C (Fig. 1). 2. While foraging for pollen fromSolanum dulcamara TTh was also regulated near 36 °C (Fig. 2). 3. In contrast, mean TTh ofB. terricola foraging fromSpiraea latifolia andSolidago canadensis varied nearly directly with ambient thermal conditions (Figs. 4 and 5). 4. Abdominal temperature varied nearly directly with TA regardless of whether or not TTh was stabilized (Figs. 1 and 4). 5. At TA<21 °C in shade many of the nectar foragers onSolidago canadensis andSpiraea latifolia, having a TTh < 29 °C, were incapable of immediate flight. However, the TTh of pollen gatherers at the same TA (Table 1) was higher (p < 0.01), and these bees were always capable of immediate flight. 6. The energetic costs for temperature regulation during foraging at different TA, and the energetic gains that might be derived are discussed (see Figs. 7 and 8) in relation to the geometry of nectar distribution in space, and in relation to nectar abundance.

Physiological aspects of sound communication in crickets ( Gryllus campestris L.)

Abstract: The ability of the cricket ear to code different sound stimulus parameters has been investigated and compared with the song parameters of the natural cricket songs.

Aerobic and anaerobic metabolism during activity in the lizardDipsosaurus dorsalis

Abstract: 1. Oxygen consumption and lactate content of the lizardDipsosaurusdorsalis were determined under standard conditions and for a bout of maximal activity induced by a 2-min period of electrical stimulation. Observations were made between 25 ° and 45 °C. 2. Maximal aerobic scope, 2.27 cm3 O2/(g × hr), occurred at 40 °C (Figs. 2, 4). The increase in oxygen consumption during activity at the various temperatures between 25 ° and 45 °C represented 7- to 17-fold of corresponding resting levels. 3. Lactate content of restingDipsosaurus is independent of temperature and averages 0.25 mg/g body weight. Maximal lactate production during the activity induced by a 2-min period of electrical stimulation occurred at 40 °C (Fig. 3). The capacity ofDipsosaurus for anaerobic metabolism exceeds that of other lizards investigated, both in its magnitude and in its thermal dependence. 4. The total amount of energy mobilized byDipsosaurus in the activity induced by a 2-min period of electrical stimulation was maximal at 40 °C (Fig. 4). Anaerobiosis accounts for a minimum of 58–83% of the total energetic expenditure. 5. It is postulated that the principal physiological adaptations to preferred thermal levels in reptiles have involved energy mobilization during and rapid recovery after activity.

Water and electrolyte budgets of a free-living desert lizard,Sauromalus obesus

Abstract: 1. Seasonal water metabolism in the herbivorous desert lizardSauromalus obesus (chuckwalla) was measured with tritiated water (HTO). Electrolyte budgets were obtained from field and laboratory measurements. These data describe the roles of various excretory organs in maintaining balance and permit evaluation of some aspects of the physiological ecology of these lizards. 2. When vegetation was succulent, chuckwallas obtained more than enough water from their food to meet their needs (Table 5). The excess was excreted rather than being stored (Table 1). 3. Although water requirements of chuckwallas maintaining constant weights are low in comparison to some other desert vertebrates, metabolic water production is insufficient to balance losses. These lizards must eat succulent vegetation to maintain water balance. 4. When vegetation was dry (summer), chuckwallas remained in crevices most of the day and did not eat. This behavior resulted in a considerable reduction in water loss. 5. These lizards did not drink rain water. 6. During drought, chuckwallas became dehydrated (Fig. 2), but fractional fluid volumes were maintained at normal levels (Table 1), as were plasma electrolyte concentrations (Table 2). 7. Chuckwallas entered winter dens in October weighing only two-thirds as much as in April (Fig. 1). They did not grow in length during 1970. 8. The diet was always hyperosmotic with K+ predominating, but this load was excreted by the nasal salt glands and as precipitated potassium urate (Table 7). These avenues of electrolyte loss require little water (Table 6), resulting in effective separation of water excretion from electrolyte excretion.

Compound Slit Sense Organs on the Spider Leg: Mechanoreceptors Involved in Kinesthetic Orientation

Abstract: 1. The hunting spiderCupiennius salei Keys is able to direct its locomotion by making use of information about its own previous movement sequences (kinesthetic orientation). After a blinded spider is chased ca. 25 cm away from a prey-fly, it returns to the original capture site despite the preclusion of other possible orientation clues. The mean starting direction of such returns differs from the ideal return direction by only 2 ° (Fig. 4a, 5). Of all runs 95% are “successful” in that the animals approach the capture site as close as 5 cm (mean value) (Fig. 3). 2. Mechanical destruction of compound slit sense (“lyriform”) organs on femur and tibia of all legs results in disorientation of the spiders: more than 2/3 of their returns pass the capture site at a distance of more than 10 cm (Fig. 3, 4b). In addition, the mean angular deviation of starting directions increases significantly. The difference between the mean starting angles of the treated groups and the mean of intact animals, however, is significant only in some cases. 3. A special effort was made to evaluate not only thestarting directions and the “success” of a return path, but theentire return route, which is comprised of several path segments based upon each stopping and/or turning point. To this end a “walking error” en was determined for each segment (Fig. 8). For intact animals the error increases abruptly at the point nearest to the capture site. We therefore conclude that the spiders control also their walking distance kinesthetically. In the case of operated animals the mean “walking error” calculated from those segments lying before the “nearest point” increases by a factor of 4 to 5, as compared with intact spiders, whereas it remains about the sameat the “nearest point” itself (Fig. 9). 4. Small holes pierced into the leg cuticle near intact lyriform organs of otherwise intact “control animals” do not influence the success, starting angle, and walking errors of returns.

Lateral inhibition in an insect eye

Abstract: Intracellular light-evoked potentials were measured from both visual cells and secondary neurons (monopolar neurons type I) in the eye of Calliphora at varying angles of light-incidence. From these measurements and from the characteristic curves we obtained a relationship between the effective light intensity and the angle of incidence of the light stimulus for both cell types. These curves must be identical for the two cell types in the absence of a lateral information processing as a theoretical reflection shows. From the experimental results that the curve (effective light intensity versus light angle of incidence) of the monopolar neurons was considerably narrower as that of the visual cells, it was concluded that a lateral inhibition in the first optic ganglion of the fly retina exists. Although the information coding in the secondary neurons of the fly retina was completely different (graded potentials) from that of corresponding neurons in the Limulus eye (spikes), it appeared that the same principles of information processing existed in both instances.

Aggressiveness as a function of external stimulation

Abstract: The attack readiness of a male cichlid, as measured by the rate of attacks directed at small blinded test fish, falls to a very low level if the animal is isolated from adult conspecifics for several weeks. It recovers again within a few days after repeated exposure to adult conspecifics. This readiness to attack could also be restored by repeated presentation of fish dummies, resembling a territorial conspecific male, over a period of 10 successive days. After being raised by this procedure, the attack readiness returned to its prestimulatory level with a half time of 7 days. Theoretical implications and the ecological significance of this long term process are discussed.

A virtuoso isopod

Abstract: An extremely elaborate performance, involving endogenous timing with both tidal and lunar frequencies, has been recorded in the locomotor activity of an adult specimen of the intertidal isopod,Excirolana chiltoni. During two months of observation, under constant, non-tidal conditions, this animal showed a persistent tidal rhythm in its swimming activity. Bursts of activity were initially well synchronized with times of tide crest on the shore. The average free-running period of the tidal rhythm was about 24 h 55 min, i.e. about 5 minutes longer than the average period of the tides; thus, the loss of synchrony with the concurrent tides was very gradual. The amount of activity per burst showed a conspicuous pattern of variation, a periodic amplitude modulation which paralleled, in detail, the complex lunar cycle of changes in height of high tide. The free-running period of the bimodal, circa-lunar rhythm of amplitude modulation was one or two days longer than the natural 29-day lunar cycle of tide heights. Each feature of this recording has been qualitatively replicated in activity records from other individuals of this species. Freshly-collectedExcirolana generally show spontaneous bursts of activity at times of tide crest, bursts which are repeated as a persistent tidal rhythm, the period of which commonly departs by only a few minutes from that of the natural tidal cycle. Superimposed on the tidal rhythm is an endogenous monthly pattern of amplitude modulation, which alters the amount of activity per burst. This circa-lunar rhythm has a free-running period between about 26 and 33 days, and generally leads to maximum activity on days of highest of high tides. The net result of the tidal and lunar rhythms is an activity pattern which permits the isopods to recapitulate, in great detail, certain significant ecological aspects of the mixed, semi-diurnal tidal regime of California. The experimental data are not compatible with the hypothesis that uncontrolled environmental factors, such as vibrations from waves, were responsible for the rhythmic behavior of the animals. Neither do the data support the hypothesis that “beats” between the observed tidal rhythm and a hidden daily or circadian rhythm were responsible for the observed circa-lunar rhythm. Furthermore, the pattern of the circa-lunar rhythm cannot be accounted for by a single monthly oscillation in the “excitability” of the animals, such as might be mediated by changes in the level of an excitatory or inhibitory hormone in the circulatory system.

Respiratory adaptations of a fossorial mammal, the pocket gopher (Thomomys bottae)

Abstract: 1. Fossorial rodent burrows exhibit relatively stable environmental conditions with regard to light, y. However, vastly different concentrations of CO2 and O2 are encountered in these burrows. Field observations of shallow pocket gopher burrows (Thomomys bottae) reveal CO2 concentrations to 3.8%, and O2 concentrations from 15.5% to 20.5% (Darden, 1970). Values similar to these have been reported for another genus of gopher,Geomys, by Kennerly (1964) and McNab (1966). 2. The sensitivity of the respiratory control mechanisms of the pocket gopher (T. bottae) O2 was tested and expressed as percent increase in minute volume as a function of the level of inspired CO2 (2% to 8%). The CO3 response curve is markedves for other terrestrial and diving mammals (Figs. 1 and 3). 3. Except for a reduction in slope, the respiratory response to CO2 of gophers can be described as similar to that recorded for humans. Carbon dioxide stimulates both increased ventilatory frequency and tidal volume in a near linear fashion. Individual difference in CO2 sensitivity among gophers was demonstrated (Table 2). 4. The level of alveolar CO2 (PA,CO2) in anesthetized pocket gophers is not significantly altered from values normally observed in man at sea level (Table 4). The reduced ventilatory response is due to a reduction in the slope of the response curve. The possible causes for the decreased sensitivity are discussed. 5. Comparisons of predicted and observed values of tidal volume (VT), rate of ventilation (f), minute volume (\(\dot V_{\min } \)) and respiratory dead space (VD) were made (Table 3). Of these,VD and f and consequently\(\dot V_{\min } \) were smaller than expected. The reduced value ofVD offsets the low\(\dot V_{\min } \) and thus alveolar ventilation (\(\dot V_A \)) is only slightly lower than expected. The possible biological significance of the alterations in f andVD are discussed.

Dorsoventral asymmetry in the visual field of the bee,Apis mellifica

Abstract: 1. Bees can be trained to a special orientation αtr of a black-and-white disk (one half black, the other half white; angular diameter 130 °), offered on a vertical screen. Different test inclinations αt of the contrast line between the black and white area of the disk are discriminated from αtr (direction sensitivity curve, Figs. 3 and 4). 2. Insertions of contrasting sectors into the black and white area of the training pattern diminish the reaction frequency to that pattern (W- and B-functions, Figs. 6 and 7). Therefore the direction sensitivity curve can be approximately calculated by means of the B- and W-functions, because a rotation of the black-and-white disk is accompanied by the insertion of a white sector in the previously black area and vice versa (Fig. 5). 3. The effect of inserting contrasting areas in the black-and-white disk is the stronger, the more these insertions are located in the medial lower part of the visual field (Fig. 9, Tables 3 and 4). 4. The results provide strong evidence for the conclusion that the different positions of the visual field are topographically represented in the central nervous system of the bee, and that the middle lower part of the frontal visual field is most decisive for pattern recognition. They do not agree with the classical theory of form perception in insects, which is based on an integration of the stimuli effects all over the visual field, irrespective of their position within the visual field.

Entrainment of the circadian locomotor activity rhythm in crayfish

Abstract: 1 Crayfish (Procambarus clarkii) on a light cycle (LD 12∶12) exhibit a bimodal locomotor activity rhythm One activity maximum, the “lights-on” peak, is synchronized with the onset, while the other, the “lights-off” peak, occurs shortly after the offset of light (Figs 1–5) 2 When placed in constant darkness (DD), these animals maintain a unimodal, free running circadian rhythm, involving only the “lights-off” peak of activity (Fig 1) 3 Removal, or isolation from the CNS, of the sixth abdominal ganglion (the site of the caudal photoreceptor) has no observable effect on activity (Figs 2, 3), indicating that the caudal photoreceptor is not necessary for entrainment or initiation of either activity maximum 4 Removal of the ommatidia of both eyes, or bilateral section of the optic lobes between the lamina ganglionaris and medulla externa, obliterates the “lights-on” peak but does not affect entrainment of the “lights-off” response Thus, the retina provides the necessary pathway for generating the “lights-on” activity, but is not required for entrainment of the circadian rhythm (Figs 4, 5) 5 Finally, ablation of both the caudal ganglion and the retina does not abolish entrainment It is assumed, therefore, that crayfish possess an extraretinal-extracaudal photoreceptor which provides a sufficient pathway for the entraining signal (Figs 4, 5)

Pinealectomy abolishes the circadian rhythm of migratory restlessness

Abstract: Pinealectomy of White-throated Sparrows (Zonotrichia albicollis) free-running under constant conditions in dim light abolishes the circadian rhythm of nocturnal spring and fall migratory restlessness (Zugunruhe) as well as the rhythm of summer “daytime” locomotor activity (Pigs. 1 and 2). Rhythmicity persists in sham-operated birds. Pinealectomized birds are synchronized by a light cycle but their activity rhythm decays to arrhythmicity when they are released from entrainment into constant dim light. The pineal of the white-throat seems essential for the expression of circadian rhythms of both “daytime” activity and migratory restlessness. These findings support the hypothesis that the avian pineal is fundamentally involved in circadian organization.

The jamming avoidance response of high frequency electric fish: II. Quantitative aspects

Abstract: Summary1.Using a frequency difference (ΔF) clamp to maintain a stimulus and frustrate the normal escape from a jamming frequency, the response is found to be a characteristic function of the δF between stimulus and fish (Figs. 2, 3, 4, 6). It is graded on both sides of a best ΔF of about 3 Hz (=0.3% inSternarchus, 1.0% inEigenmannia). There is no systematic response whenFstimulus =Ffish,regardless of phase.2.The J. A.R. is graded with intensity (voltage gradient) of the stimulus over a range of more than 100-fold; higher intensities cause some reduction (Fig. 5). The threshold for longitudinal stimulation under certain conditions is lower than 0.25 μV (peak to peak)/cm; for transverse stimulation as in most of the present experiments 0.5 μV (peak to peak)/cm.3.The best ΔF is the same when added to the fundamental of any harmonic (response detectable at least to the fifth) (Fig. 6). Stimulation around a subharmonic does not elicit the J.A. R.4.A response to a small ΔF, e.g. 0.2 Hz, can begin within < 1/4 cycle of the beat frequency and, without “hunting”, shift in the correct direction.5.Stimulating with an optimal beat-frequency by amplitude modulation (AM) of a stimulus atFfish, with an AM frequency of 3 Hz, can cause a response though it is confused as to sign. If the stimulus frequency unmodulated is at a ΔF=−20 Hz and therefore almost ineffectual, AM at 17 Hz will cause a response upwards and at 23 Hz downwards (Eigenmannia). These results and the following suggest the fish performs the equivalent of a Fourier analysis and responds to sidebands according to their ΔF.6.In a 300 HzEigenmannia, if an ineffective stimulus at 280 Hz (ΔF=−20 Hz) is frequency modulated (FM) sinusoidally at 17 Hz between peaks of about 274 and 286 Hz, the fish gives an upwards J.A.R.7.By curarizingEigenmannia to silence its electric organ we can apply a phase modulated stimulus - a carrier wave whose cycles are systematically phase shifted by a few degrees back and forth at a few Hz. This also causes a response, though only in one direction.8.If a stimulus is slowly frequency modulated (FM≪ΔF) e.g. between ΔF = + and −6 Hz sinusoidally or triangularly at 10 to 100 sec per cycle, the fish responds and theFfish/ΔF plot traces an hysteresis loop. This is quite well predicted by an analog computer model embodying the best ΔF curve and the time course of response to a ΔF step stimulus (Fig. 7).Unclamped behavior is similar (Figs. 9,10) and predictable from the responses to step stimuli in the clamped condition.10.A block diagram putting the distinguishable properties into sequence is offered (Fig. 11).

In vivo Studies on the Release of Hormones from the Corpora Cardiaca of Locusts

Abstract: Sectioning of the afferent nerves (NCCl and NCCll) to the locust corpus cardiacum prevents thein vivo release of adipokinetic hormone from the glandular lobes. This failure to release the hormone during flight and the consequent lack of lipid mobilisation brings about an impairment of flight performance which can be corrected by injections of corpus cardiacum extracts. Sectioning of the NCCl and NCCll reduces markedly the activity of the corpora allata. However, the poor flight performance of allatectomised locusts is not related to an inability to mobilise lipid since injections of corpus cardiacum extract which will mobilise fat body lipid in these locusts have no effect on flight performance. The results of individual sectioning of the NCCl and NCCll suggest that a double innervation of the glandular lobes functionsin vivo to control adipokinetic hormone release but that the NCCl alone may control the release of the diuretic hormone.

Renal failure as the cause of death inTupaia belangeri exposed to persistent social stress

Abstract: 1. An adult male Tupaia belangeri was introduced to another male which was an experienced fighter. The latter immediately attacked the newcomer and subjugated him (Figs. 1 and 2). The two animals were subsequently separated, so that the subordinate animal could see the victor permanently, but could not be attacked by him. The fight and subjugation were repeated every 1-2 days, in order to maintain dominance relationships. Changes in physiological parameters were determined by sacrificing some of the tree-shrews at 2-16 days after the first subjugation, 80-100 minutes before the onset of daily activity. 2. After the first subjugation, subordinate animals lie still in a corner for more than 90 % of the daily activity-phase and follow the movements of the victors with their heads. The tail-hair is continuously raised, indicating persistent activation of the sympathetic nervous system. Subordinate animals eat as long as controls. 3. After 2-16 days, the skin-temperature of the subordinates abruptly falls from more than 35~ to less than 30~ within 24 hours. Cramps and paralysis appear in the extremities, the tree-shrews fall into coma and die. Wounds can be excluded as the cause of death. 4. The following physiological changes take place in the subordinate animals: a) The animals lose body weight in a linear fashion. The rate of weight-loss varies considerably between animals (Fig. 3). The more weight an animal loses daily, the more rapidly it dies (r ~ 0.89; Fig. 4). Death is not a result of inadequate energy-supply (resp. hypoglyeaemia). b) In subordinates, the glycogen content of the liver is significantly below that of controls (p~0.003; Table 1); but even dying animals may exhibit normal glycogen values. The glucose concentration of the blood is the same under both conditions (Table 1). c) The haemoglobin content of the blood decreases during stress exposure (r ~ 0.75; Fig. 5). The decrease is the more rapid, the more weight a subordinate animal loses daily (r~0.68). The decrease in haemoglobin concentration is primarily due to haemolysis, but erythropoiesis is also restricted (Table 2). d) The kidney weight decreases with continued stress; animals sacrificed more than 10 days after their first subjugation have kidneys approximately 17 % lighter than those of controls (p < 0.05; Fig. 8). e) During the course of stress, urea-N content of the blood increases (Fig. 6). The more rapidly the urea-N increases, the more rapid is the decrease in blood haemoglobin content ( r ~ 0.89). Subordinate animals can move around normally with values up to 150 mg urea-N/100 ml blood, and they look healthy. If the concentration rises above this level, symptoms of imminent death appear, and the animals die.

The CNS Photoreceptor of crayfish: Morphology and synaptic activity

Abstract: Morphological and physiological evidence is presented which adds to our understanding of the responses exhibited by the caudal photoreceptor (CPR) interneuron of the crayfish. Illumination of a restricted area of the 6th abdominal ganglion showed that the CPR responds to light from only a part of the ipsilateral half of the ganglion. From Procion Yellow injections, the CPR neuron was found to consist of a contralateral cell body and an extensive ipsilateral dendritic tree. Significantly, the ganglionic area of light sensitivity was found to correspond closely to the dendritic domain. Electrical responses were recorded intracellularly from the CPR within the neuropil, both as a result of naturally evoked photic and mechanoreceptive input and of direct electrical stimulation of the ganglionic roots. When light was the predominant input, membrane depolarization of the CPR was gradual and smooth, reaching 8–10 mV and triggering trains of spikes. Electrical stimuli applied to the ipsilateral 1st through 5th roots of abdominal ganglion six produced monosynaptic EPSP's while stimuli to the corresponding contralateral roots evoked IPSP's. Recruitment of excitatory units was seen with increasing intensity; trains of stimuli showed summation. These inputs apparently originated from tactile hairs on the caudal appendages which were shown in the present study to be directionally sensitive. Several unidentified interneurons in abdominal ganglion six were also seen to respond to directional fluid movements over the caudal appendages, in much the same manner as did the CPR. Evidence for the presence of other light-sensitive interneurons is also presented. The data suggest that the CPR itself is transducing the light input.

Die Atmung beim KolibriAmazilia fimbriata während des Schwirrfluges bei verschiedenen Umgebungstemperaturen

Abstract: An schwirrenden Kolibris (Amazilia fimbriata fluviatilis, mittleres Gewicht 5,7 g) wurden O2-Verbrauch, CO2-Produktion, Atemfrequenz, respiratorische Wasserabgabe und Flugelschlagfrequenz gemessen. Die Versuche wurden bei Temperaturen von 0–35 ° C durchgefuhrt.

Comparative behavioral studies on two visual mutants of Drosophila

Abstract: Phototaxis and optomotor reactions of the mutantsebony and opm 2 are investigated. LikeMusca, Drosophila has two complementary visual input systems, one specialized (e. g.) in optimal contrast transfer (high acuity system, HAS, retinula cells 7 and 8) the other in high sensitivity (HSS, retinula cells 1–6). Inebony the HSS seems to be blocked for phototaxis and optomotor responses (Figs. 1 A, 5). However, even the HAS has a higher threshold intensity than in wild type (Fig. 5). In opm 2 the HSS is disturbed for phototaxis (Fig. 1) but is operating for the optomotor response (Fig. 6). However the HAS seems to be largely suppressed for the optomotor response (Table 2). In the double mutantebony-opm 2 both visual input systems seem to be impaired for movement detection (Fig. 7). Two other properties of the visual system of opm 2 are described. The visual fields of the sampling stations for movement detection are about twice as large as in wild type (Figs. 2A, B). This can not be explained by a disturbance of the optics. In other mutants of this type the visual field size is slightly different. In opm 2 the reaction to movement from front to back (progressive) is specificly suppressed, whereas, at least in flight, the reaction to movement from back to front (regressive) is normal (Table 1, Figs. 3, 4). The degree of suppression of the reaction to progressive movement is variable in individual flies and differs for the three mutants of the opm 2-group (Table 1). In a simple example the use of these mutants for system analysis experiments is demonstrated.