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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 89 (1974), S. 331-357 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Chases in which male flies (Fannia canicularis) pursue other flies were studied by filming such encounters from directly below. Males will start to chase whenever a second fly comes within 10–15 cm (Fig. 3). 2. Throughout these chases there was a continuous relationship between the angle (θ e ) made by the leading fly and the direction of flight of the chasing fly, and the angular velocity of the chasing fly (ω f ). This relation was approximately linear, with a slope of 20 ° s−1 per degree θ e (Figs. 4–7). 3. The maximum correlation between ω f and θite occurs after a lag of approximately 30 ms, which represents the total delay in the system (Fig. 8). 4. In the region close to the chasing fly's axis (θite less than about 35 °) a second mechanism exists in which the angular velocity of the chasing fly (ω f ) is controlled by the relative angular velocity of the leading fly (ω e ), rather than its relative position. The ratio of ω f to ω e in this region is approximately 0.7. 5. Using the results in 2–4 above, and an empirically determined relation between the angular and forward velocities of the chasing fly, it was possible to simulate the flight path of the chasing fly, given that of the leading fly (Fig. 11). Because these simulations predict correctly the manoeuvres and outcomes of quite complicated chases, it is concluded that the control system actually used by the fly is accurately described by conclusions 2–4. 6. The physiological implications of this behaviour, and the possible function of chasing, are discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 99 (1975), S. 1-66 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The visually guided flight behaviour of groups of male and femaleSyritta pipiens was filmed at 50 f.p.s. and analysed frame by frame. Sometimes the flies cruise around ignoring each other. At other times males but not females track other flies closely, during which the body axis points accurately towards the leading fly. 2. The eyes of males but not females have a forward directed region of enlarged facets where the resolution is 2 to 3 times greater than elsewhere. The inter-ommatidial angle in this “fovea” is 0.6°. 3. Targets outside the fovea are fixated by accurately directed, intermittent, open-loop body saccades. Fixation of moving targets within the fovea is maintained by “continuous” tracking in which the angular position of the target on the retina (Θ e) is continuously translated into the angular velocity of the tracking fly ( $$\dot \Phi _p $$ ) with a latency of roughly 20 ms ( $$\dot \Phi _p = k \Theta _e $$ , wherek≏30 s−1). 4. The tracking fly maintains a roughly constant distance (in the range 5–15 cm) from the target. If the distance between the two flies is more than some set value the fly moves forwards, if it is less the fly moves backwards. The forward or backward velocity ( $$\dot F_p $$ ) increases with the difference (D-D 0) between the actual and desired distance ( $$\dot F_p = k^\prime (D - D_0 )$$ ), wherek′=10 to 20 s−1). It is argued that the fly computes distance by measuring the vertical substense of the target image on the retina. 5. Angular tracking is sometimes, at the tracking fly's choice,supplemented by changes in sideways velocity. The fly predicts a suitable sideways velocity probably on the basis of a running averageΘ e , but not its instantaneous value. Alternatively, when the target is almost stationary, angular tracking may bereplaced by sideways tracking. In this case the sideways velocity ( $$\dot S$$ ) is related toΘ e about 30 ms earlier ( $$\dot S_p = k\prime \prime \Theta _e $$ , wherek″=2.5 cm · s−1 · deg−1), and the angular tracking system is inoperative. 6. When the leading fly settles the tracking fly often moves rapidly sideways in an arc centred on the leading fly. During thesevoluntary sideways movements the male continues to point his head at the target. He does this not by correctingΘ e , which is usually zero, but by predicting the angular velocity needed to maintain fixation. This prediction requires knowledge of both the distance between the flies and the tracking fly's sideways velocity. It is shown that the fly tends to over-estimate distance by about 20%. 7. When two males meet head on during tracking the pursuit may be cut short as a result of vigorous sideways oscillations of both flies. These side-to-side movements are synchronised so that the males move in opposite directions, and the oscillations usually grow in size until the males separate. The angular tracking system is active during “wobbling” and it is shown that to synchronise the two flies the sideways tracking system must also be operative. The combined action of both systems in the two flies leads to instability and so provides a simple way of automatically separating two males. 8. Tracking is probably sexual in function and often culminates in a rapid dart towards the leading fly, after the latter has settled. During these “rapes” the male accelerates continuously at about 500 cm · s−2, turning just before it lands so that it is in the copulatory position. The male rapes flies of either sex indicating that successful copulation involves more trial and error than recognition. 9. During cruising flight the angular velocity of the fly is zero except for brief saccadic turns. There is often a sideways component to flight which means that the body axis is not necessarily in the direction of flight. Changes in flight direction are made either by means of saccades or by adjusting the ratio of sideways to forward velocity ( $$\dot S/\dot F$$ ). Changes in body axis are frequently made without any change in the direction of flight. On these occasions, when the fly makes an angular saccade, it simultaneously adjusts $$\dot S/\dot F$$ by an appropriate amount. 10. Flies change course when they approach flowers using the same variety of mechanisms: a series of saccades, adjustments to $$\dot S/\dot F$$ , or by a mixture of the two. 11. The optomotor response, which tends to prevent rotation except during saccades, is active both during cruising and tracking flight.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Neuroscience 15 (1992), S. 1-29 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillian Magazines Ltd.
    Nature 401 (1999), S. 470-473 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Some insects and vertebrates use the pattern of polarized light in the sky as an optical compass. Only a small section of clear sky needs to be visible for bees and ants to obtain a compass bearing for accurate navigation. The receptors involved in the polarization compass are confined to a ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 263 (1976), S. 764-765 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Live Oplophorus spinosus (Coutire), about 5 cm long, were obtained from trawls at a depth of 500 m in the North Atlantic during a recent cruise of the RRS Discovery (JulyAugust 1976). The eyes are almost spherical, and when illuminated they exhibit a bright orange glow over a circular area whose ...
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 137 (1980), S. 255-265 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Euphausiids (Nematoscelis atlantica) move their eyes through 180° in response to the movement of a small light source. In the sea the effect would be for the upper eye to track the direction of the downwelling light (Figs. 1 and 2). The ventral photophores always rotate in synchrony with the eyes and through the same angle. 2. The tail also follows movements of the light, but only when the eye is in particular positions in its orbit. As the eye moves backwards the tail moves up and vice versa (Figs. 3 and 4). The effect of the tail movements on a freely rotating animal is to cause the body to maintain a constant angle to the light (Figs. 5 and 8). 3. The eye movements have a latency of about 80 ms, and maximum angular velocities of about 200°s−1. Tail movements are synchronous with eye movements, but the effect of the rudder action is slow so that corrective body movements may take several seconds to complete (Figs. 5 and 6). 4. Different animals maintain different body angles with respect to the light. It is assumed that these angles represent different phases of diurnal migration. The one parameter that changes when a new course is adopted is the position of the eye in the orbit about which tail movements are initiated. This can be represented as a variable set-point in the feedback loop that controls the action of the tail (Fig. 9). This system of steering is formally similar to the way a helmsman steers a boat with the aid of a compass (Fig. 8). 5. During tail flips this closed-loop navigation system is over-ridden by a programme in which eye and tail move in the same direction, and with different time courses. This is interpreted as a mechanism for ensuring that the eye continues to point upwards during the rapid phase of the movement that results from the tail flip (Fig. 7), and which the closed-loop mechanism would be too slow to deal with.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 125 (1978), S. 191-204 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Males of many species of hoverfly hover in one spot ready to pursue passing objects, presumably in order to catch a mate. We have filmed two of the larger species as they begin their pursuit of an approaching projectile shot at them from a peashooter. Flies do not turn and fly towards the projectile as they would if they were tracking (Land and Collett, 1974). Instead they adopt an interception path, accelerating at a uniform rate (30–35 m · s−2) approximately in the direction in which the target is moving (Fig. 1). 2. If the projectile is made to reverse direction, the male does not respond to the change in the target's course for about 90 ms (Fig. 2). Thus, in contrast to the situation later (Fig. 3), the start of a pursuit is not under continuous sensory control. The fly selects its course when it first sees the target and maintains its interception path as an open-loop response. 3. Males only need to catch conspecifics and can thus assume that their quarry has a typical speed and, since it is of a uniform size, will be detected at a predetermined distance. These assumptions mean that the approach angle of the target at the moment of first sighting can be specified by the image velocity of the target across the retina ( $$\dot \theta _e $$ ). Since the male also “knows” its own acceleration, the direction of flight which will enable it to intercept the target can also be specified in terms of the initial position (θ e) and velocity ( $$\dot \theta _e $$ ) of the target image (Figs. 6 and 7). 4. We show that interception should occur if the male obeys the simple rule that the size of the turn it makes (Δφ) is given by $$\Delta \phi \simeq \theta _e - 0.1{\text{ }}\dot \theta _e \pm 180^\circ $$ . Our data indicate that the initial turns of the males do obey this rule (Fig. 8), and that males are “designed” to catch females travelling at about 8 m · s−1. 5. If males are calibrated to catch targets of a particular size and speed, they will be unable to intercept projectiles that are very different in these respects. When large, slowly moving projectiles are launched to pass by the fly, its attempted interception path is predictably inappropriate (Fig. 9).
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 156 (1985), S. 525-538 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The directions of the axes of all ommatidia in the frontal eye regions of 2 species of fly (Calliphora erythrocephala andLucilia cuprina, both sexes) were mapped onto the surface of a sphere. This was done by photographing the pseudopupil in white-eyed mutants. 2. In both sexes of both species there is a region with a high density of ommatidial axes (an acute zone), situated frontally and slightly above the equator. In females the centre of this region is only about 5° above the equator (Lucilia andCalliphora); its location is similar in maleLucilia, but is 15° higher in maleCalliphora. The maximum density of ommatidial axes is about 1 per deg2 inLucilia (both sexes) andCalliphora males; it is lower inCalliphora females (0.7 per deg2). These densities are roughly 3 times higher than at 60° from the front. 3. We have used the data given by Beersma et al. (1975), to produce a similar map for a maleMusca domestica. The results differ from the other species mainly in that the overall density is lower, the maximum being 0.4 axes per deg2, 20–25° above the equator. 4. Using these data and others from the literature we arrive at the following conclusions: (i) the regions of highest resolution and highest ommatidial diameter coincide closely, (ii) the region of greatest binocular overlap lies well above the centre of the acute zone, 20° higher in maleCalliphora. (iii) the ‘7r domain’ in maleMusca (Hardie et al. 1981) corresponds closely with the acute zone, (iv) the fields of view of the male-specific lobula interneurones MLG3 and Col D (Hausen and Strausfeld 1980) include the acute zone centre but also most of the dorsal part of the field of view. This is consistent with a function related to chasing. 5. Differences in function of male and female acute zones are discussed. It seems likely that there are two kinds of acute zone in insect eyes, one concerned with forward flight and the other with the detection and capture of other insects. We also argue that ‘fovea’ should not be used to mean a region of high ommatidial axis density.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 160 (1987), S. 355-357 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary It is possible to project a horizontal line of light onto a moth's cornea and simultaneously a vertical line onto the retina (Fig. 1). In the dark adapted eye of a sphingid moth (Theretra latreilli) this resulted in the appearance of a horizontal line of pigment across the eye (Fig. 2). This proves that the trigger for pigment migration is near the cornea, presumably in the pigment cells themselves, and not in the receptors.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 167 (1990), S. 155-166 
    ISSN: 1432-1351
    Keywords: Vision ; Eye-movement ; Stomatopod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Odontodactylus scyllarus makes discrete spontaneous eye-movements at a maximum rate of 3/s. These movements are unpredictable in direction and timing, and there is no detectable co-ordination between the two eyes. The eye-movements were measured with a computer-aided video method, and from 208 of these the following picture of a typical movement emerges. It has roughly equal horizontal and vertical components of 7–8°, taking the eye-stalk axis about 12° around a great circle, and also a rotational component of about 8°. The 3 components can occur independently of each other and are thus separately driven by the brain (Fig. 6). The average duration is 300 ms, and average velocity is 40° s (Fig. 5). Most movements are made in a direction approximately at right angles to the orientation of the specialised central band. It is shown that the slow speed of the eye-movements is compatible with scanning, that is, the uptake of visual information during the movement rather than its exclusion as in conventional saccades. Mantis shrimps also make target-acquiring and tracking eye-movements which tend to be somewhat larger and faster than other spontaneous movements. Rotating a striped drum around the animal induces a typical optokinetic nystagmus whose slow phases are smooth, unlike target tracking which is jerky (Fig. 7). Eye-movements may therefore be conveniently grouped into 3 classes: targetting/tracking, scanning, and optokinetic.
    Type of Medium: Electronic Resource
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