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Rudiger Wehner - One of the best experts on this subject based on the ideXlab platform.
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Vision in the nocturnal wandering spider Leucorchestris Arenicola (Araneae: Sparassidae).
The Journal of experimental biology, 2020Co-Authors: Thomas Norgaard, Daneric Nilsson, Joh R Henschel, Anders Garm, Rudiger WehnerAbstract:At night the Namib Desert spider Leucorchestris Arenicola performs long-distance homing across its sand dune habitat. By disabling all or pairs of the spiders' eight eyes we found that homing ability was severely reduced when vision was fully abolished. Vision, therefore, seems to play a key role in the nocturnal navigational performances of L. Arenicola. After excluding two or three pairs of eyes, the spiders were found to be able to navigate successfully using only their lateral eyes or only their anterior median eyes. Measurement of the eyes' visual fields showed that the secondary eyes combined have a near full (panoramic) view of the surroundings. The visual fields of the principal eyes overlap almost completely with those of the anterior lateral eyes. Electroretinogram recordings indicate that each eye type contains a single photopigment with sensitivity peaking at approximately 525 nm in the posterior and anteriomedian eyes, and at approximately 540 nm in the anteriolateral eyes. Theoretical calculations of photon catches showed that the eyes are likely to employ a combination of spatial and temporal pooling in order to function at night. Under starlit conditions, the raw spatial and temporal resolution of the eyes is insufficient for detecting any visual information on structures in the landscape, and bright stars would be the only objects visible to the spiders. However, by summation in space and time, the spiders can rescue enough vision to detect coarse landscape structures. We show that L. Arenicola spiders are likely to be using temporal summation to navigate at night.
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vision in the nocturnal wandering spider leucorchestris Arenicola araneae sparassidae
The Journal of Experimental Biology, 2008Co-Authors: Thomas Norgaard, Daneric Nilsson, Joh R Henschel, Anders Garm, Rudiger WehnerAbstract:At night the Namib Desert spider Leucorchestris Arenicola performs long-distance homing across its sand dune habitat. By disabling all or pairs of the spiders' eight eyes we found that homing ability was severely reduced when vision was fully abolished. Vision, therefore, seems to play a key role in the nocturnal navigational performances of L. Arenicola . After excluding two or three pairs of eyes, the spiders were found to be able to navigate successfully using only their lateral eyes or only their anterior median eyes. Measurement of the eyes' visual fields showed that the secondary eyes combined have a near full (panoramic) view of the surroundings. The visual fields of the principal eyes overlap almost completely with those of the anterior lateral eyes. Electroretinogram recordings indicate that each eye type contains a single photopigment with sensitivity peaking at ∼525 nm in the posterior and anteriomedian eyes, and at ∼540 nm in the anteriolateral eyes. Theoretical calculations of photon catches showed that the eyes are likely to employ a combination of spatial and temporal pooling in order to function at night. Under starlit conditions, the raw spatial and temporal resolution of the eyes is insufficient for detecting any visual information on structures in the landscape, and bright stars would be the only objects visible to the spiders. However, by summation in space and time, the spiders can rescue enough vision to detect coarse landscape structures. We show that L. Arenicola spiders are likely to be using temporal summation to navigate at night.
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Use of local cues in the night-time navigation of the wandering desert spider Leucorchestris Arenicola (Araneae, Sparassidae)
Journal of Comparative Physiology A, 2007Co-Authors: Thomas Norgaard, Joh R Henschel, Rudiger WehnerAbstract:Adult male Leucorchestris Arenicola can walk round-trips of several tens of meters in search of females. Most excursions end with the spiders returning to their burrow. For small animals homing over distances of several meters is theoretically impossible without the aid of external cues. It was investigated, whether the spiders use local cues or they rely solely on global cues. Individually marked male spiders were captured during their excursions and displaced several meters inside an opaque box. Ten out of twelve displaced spiders returned to their burrows. This shows that the male L. Arenicola are using local cues during their homing, as the comparatively small displacement distances could not be detected by means of global, e.g. celestial cues. In order to test whether the spiders could be using olfactory guidance, the burrows were displaced by 2 m while the spiders were out on their journeys. In 12 out of 15 experiments, the spiders did not find their burrows. These results show that the burrows do not function as olfactory beacons for the homing spiders.
Thomas Norgaard - One of the best experts on this subject based on the ideXlab platform.
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Vision in the nocturnal wandering spider Leucorchestris Arenicola (Araneae: Sparassidae).
The Journal of experimental biology, 2020Co-Authors: Thomas Norgaard, Daneric Nilsson, Joh R Henschel, Anders Garm, Rudiger WehnerAbstract:At night the Namib Desert spider Leucorchestris Arenicola performs long-distance homing across its sand dune habitat. By disabling all or pairs of the spiders' eight eyes we found that homing ability was severely reduced when vision was fully abolished. Vision, therefore, seems to play a key role in the nocturnal navigational performances of L. Arenicola. After excluding two or three pairs of eyes, the spiders were found to be able to navigate successfully using only their lateral eyes or only their anterior median eyes. Measurement of the eyes' visual fields showed that the secondary eyes combined have a near full (panoramic) view of the surroundings. The visual fields of the principal eyes overlap almost completely with those of the anterior lateral eyes. Electroretinogram recordings indicate that each eye type contains a single photopigment with sensitivity peaking at approximately 525 nm in the posterior and anteriomedian eyes, and at approximately 540 nm in the anteriolateral eyes. Theoretical calculations of photon catches showed that the eyes are likely to employ a combination of spatial and temporal pooling in order to function at night. Under starlit conditions, the raw spatial and temporal resolution of the eyes is insufficient for detecting any visual information on structures in the landscape, and bright stars would be the only objects visible to the spiders. However, by summation in space and time, the spiders can rescue enough vision to detect coarse landscape structures. We show that L. Arenicola spiders are likely to be using temporal summation to navigate at night.
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vision in the nocturnal wandering spider leucorchestris Arenicola araneae sparassidae
The Journal of Experimental Biology, 2008Co-Authors: Thomas Norgaard, Daneric Nilsson, Joh R Henschel, Anders Garm, Rudiger WehnerAbstract:At night the Namib Desert spider Leucorchestris Arenicola performs long-distance homing across its sand dune habitat. By disabling all or pairs of the spiders' eight eyes we found that homing ability was severely reduced when vision was fully abolished. Vision, therefore, seems to play a key role in the nocturnal navigational performances of L. Arenicola . After excluding two or three pairs of eyes, the spiders were found to be able to navigate successfully using only their lateral eyes or only their anterior median eyes. Measurement of the eyes' visual fields showed that the secondary eyes combined have a near full (panoramic) view of the surroundings. The visual fields of the principal eyes overlap almost completely with those of the anterior lateral eyes. Electroretinogram recordings indicate that each eye type contains a single photopigment with sensitivity peaking at ∼525 nm in the posterior and anteriomedian eyes, and at ∼540 nm in the anteriolateral eyes. Theoretical calculations of photon catches showed that the eyes are likely to employ a combination of spatial and temporal pooling in order to function at night. Under starlit conditions, the raw spatial and temporal resolution of the eyes is insufficient for detecting any visual information on structures in the landscape, and bright stars would be the only objects visible to the spiders. However, by summation in space and time, the spiders can rescue enough vision to detect coarse landscape structures. We show that L. Arenicola spiders are likely to be using temporal summation to navigate at night.
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Use of local cues in the night-time navigation of the wandering desert spider Leucorchestris Arenicola (Araneae, Sparassidae)
Journal of Comparative Physiology A, 2007Co-Authors: Thomas Norgaard, Joh R Henschel, Rudiger WehnerAbstract:Adult male Leucorchestris Arenicola can walk round-trips of several tens of meters in search of females. Most excursions end with the spiders returning to their burrow. For small animals homing over distances of several meters is theoretically impossible without the aid of external cues. It was investigated, whether the spiders use local cues or they rely solely on global cues. Individually marked male spiders were captured during their excursions and displaced several meters inside an opaque box. Ten out of twelve displaced spiders returned to their burrows. This shows that the male L. Arenicola are using local cues during their homing, as the comparatively small displacement distances could not be detected by means of global, e.g. celestial cues. In order to test whether the spiders could be using olfactory guidance, the burrows were displaced by 2 m while the spiders were out on their journeys. In 12 out of 15 experiments, the spiders did not find their burrows. These results show that the burrows do not function as olfactory beacons for the homing spiders.
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nocturnal navigation in leucorchestris Arenicola araneae sparassidae
Journal of Arachnology, 2005Co-Authors: Thomas NorgaardAbstract:When the males of the Namib Desert spider Leucorchestris Arenicola (Araneae, Sparas- sidae) reach the adult stage they undertake long nocturnal searches for females. From these searches they return to their home burrow often in a straight line only retracing a fraction of their outward path if at all. Distances of 40 m and 13 m are conservative estimates of the mean round trip length and maximum distance from the burrow. Returning to the starting point of a round trip of such length is theoretically only possible if the navigator uses external cues for positional reference. The possible involvement of a range of external cues in the male L. Arenicola was investigated. The direction of gravity, the sun, polarized sunlight, olfaction, constant wind direction and vibrational beacons are ruled out or deemed unlikely to be involved in the spiders' homing.
Joh R Henschel - One of the best experts on this subject based on the ideXlab platform.
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Vision in the nocturnal wandering spider Leucorchestris Arenicola (Araneae: Sparassidae).
The Journal of experimental biology, 2020Co-Authors: Thomas Norgaard, Daneric Nilsson, Joh R Henschel, Anders Garm, Rudiger WehnerAbstract:At night the Namib Desert spider Leucorchestris Arenicola performs long-distance homing across its sand dune habitat. By disabling all or pairs of the spiders' eight eyes we found that homing ability was severely reduced when vision was fully abolished. Vision, therefore, seems to play a key role in the nocturnal navigational performances of L. Arenicola. After excluding two or three pairs of eyes, the spiders were found to be able to navigate successfully using only their lateral eyes or only their anterior median eyes. Measurement of the eyes' visual fields showed that the secondary eyes combined have a near full (panoramic) view of the surroundings. The visual fields of the principal eyes overlap almost completely with those of the anterior lateral eyes. Electroretinogram recordings indicate that each eye type contains a single photopigment with sensitivity peaking at approximately 525 nm in the posterior and anteriomedian eyes, and at approximately 540 nm in the anteriolateral eyes. Theoretical calculations of photon catches showed that the eyes are likely to employ a combination of spatial and temporal pooling in order to function at night. Under starlit conditions, the raw spatial and temporal resolution of the eyes is insufficient for detecting any visual information on structures in the landscape, and bright stars would be the only objects visible to the spiders. However, by summation in space and time, the spiders can rescue enough vision to detect coarse landscape structures. We show that L. Arenicola spiders are likely to be using temporal summation to navigate at night.
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vision in the nocturnal wandering spider leucorchestris Arenicola araneae sparassidae
The Journal of Experimental Biology, 2008Co-Authors: Thomas Norgaard, Daneric Nilsson, Joh R Henschel, Anders Garm, Rudiger WehnerAbstract:At night the Namib Desert spider Leucorchestris Arenicola performs long-distance homing across its sand dune habitat. By disabling all or pairs of the spiders' eight eyes we found that homing ability was severely reduced when vision was fully abolished. Vision, therefore, seems to play a key role in the nocturnal navigational performances of L. Arenicola . After excluding two or three pairs of eyes, the spiders were found to be able to navigate successfully using only their lateral eyes or only their anterior median eyes. Measurement of the eyes' visual fields showed that the secondary eyes combined have a near full (panoramic) view of the surroundings. The visual fields of the principal eyes overlap almost completely with those of the anterior lateral eyes. Electroretinogram recordings indicate that each eye type contains a single photopigment with sensitivity peaking at ∼525 nm in the posterior and anteriomedian eyes, and at ∼540 nm in the anteriolateral eyes. Theoretical calculations of photon catches showed that the eyes are likely to employ a combination of spatial and temporal pooling in order to function at night. Under starlit conditions, the raw spatial and temporal resolution of the eyes is insufficient for detecting any visual information on structures in the landscape, and bright stars would be the only objects visible to the spiders. However, by summation in space and time, the spiders can rescue enough vision to detect coarse landscape structures. We show that L. Arenicola spiders are likely to be using temporal summation to navigate at night.
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Use of local cues in the night-time navigation of the wandering desert spider Leucorchestris Arenicola (Araneae, Sparassidae)
Journal of Comparative Physiology A, 2007Co-Authors: Thomas Norgaard, Joh R Henschel, Rudiger WehnerAbstract:Adult male Leucorchestris Arenicola can walk round-trips of several tens of meters in search of females. Most excursions end with the spiders returning to their burrow. For small animals homing over distances of several meters is theoretically impossible without the aid of external cues. It was investigated, whether the spiders use local cues or they rely solely on global cues. Individually marked male spiders were captured during their excursions and displaced several meters inside an opaque box. Ten out of twelve displaced spiders returned to their burrows. This shows that the male L. Arenicola are using local cues during their homing, as the comparatively small displacement distances could not be detected by means of global, e.g. celestial cues. In order to test whether the spiders could be using olfactory guidance, the burrows were displaced by 2 m while the spiders were out on their journeys. In 12 out of 15 experiments, the spiders did not find their burrows. These results show that the burrows do not function as olfactory beacons for the homing spiders.
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long distance wandering and mating by the dancing white lady spider leucorchestris Arenicola araneae sparassidae across namib dunes
Journal of Arachnology, 2002Co-Authors: Joh R HenschelAbstract:Adult males of the Dancing White Lady Spider (Leucorchestris Arenicola, Araneae, Spar- assidae) occurring in the dunes of the Namib Desert, Namibia, frequently wander far out of their 3m radius territories on dark nights. They move across bare dune slopes in search of mating opportunities and subsequently return to their burrows. In the current study, I describe the long-distance movements and navigational ability of males and examine how their wandering behavior relates to mating and inter- actions with other males. In 16 observed complete excursions, male spiders walked 51 m (median, range 16-91 m) from their burrow along a path of 134 m (42-314 m). The return path was shorter than the outgoing path, had less than ? as many turns, and rarely retraced the outgoing path. Typically, the return path across open terrain had a straight section (median 33 m, range 10-89 m) which was directed towards the home burrow with a maximum angle of deviation of 58. Males crossed 0-5 territories of adult males and as many female territories, mating in about half of the encounters with females. Males avoided each other and signaled with intense sand drumming. Adult males differ in size and there are indications that they compete with each other for mates by long-distance movements, drum-signaling each other, and interfering with mating. During three years of observations of a L. Arenicola population, 8% of the largest males did 51% of the mating. Spiders of both sexes were promiscuous, and individuals mated with each other on several occasions. The current study prompts future investigations concerning male orientation and its neurophysiological basis, their ability to locate females, as well as the inter- and intrasexual relationships of L. Arenicola.
Anders Garm - One of the best experts on this subject based on the ideXlab platform.
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Vision in the nocturnal wandering spider Leucorchestris Arenicola (Araneae: Sparassidae).
The Journal of experimental biology, 2020Co-Authors: Thomas Norgaard, Daneric Nilsson, Joh R Henschel, Anders Garm, Rudiger WehnerAbstract:At night the Namib Desert spider Leucorchestris Arenicola performs long-distance homing across its sand dune habitat. By disabling all or pairs of the spiders' eight eyes we found that homing ability was severely reduced when vision was fully abolished. Vision, therefore, seems to play a key role in the nocturnal navigational performances of L. Arenicola. After excluding two or three pairs of eyes, the spiders were found to be able to navigate successfully using only their lateral eyes or only their anterior median eyes. Measurement of the eyes' visual fields showed that the secondary eyes combined have a near full (panoramic) view of the surroundings. The visual fields of the principal eyes overlap almost completely with those of the anterior lateral eyes. Electroretinogram recordings indicate that each eye type contains a single photopigment with sensitivity peaking at approximately 525 nm in the posterior and anteriomedian eyes, and at approximately 540 nm in the anteriolateral eyes. Theoretical calculations of photon catches showed that the eyes are likely to employ a combination of spatial and temporal pooling in order to function at night. Under starlit conditions, the raw spatial and temporal resolution of the eyes is insufficient for detecting any visual information on structures in the landscape, and bright stars would be the only objects visible to the spiders. However, by summation in space and time, the spiders can rescue enough vision to detect coarse landscape structures. We show that L. Arenicola spiders are likely to be using temporal summation to navigate at night.
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vision in the nocturnal wandering spider leucorchestris Arenicola araneae sparassidae
The Journal of Experimental Biology, 2008Co-Authors: Thomas Norgaard, Daneric Nilsson, Joh R Henschel, Anders Garm, Rudiger WehnerAbstract:At night the Namib Desert spider Leucorchestris Arenicola performs long-distance homing across its sand dune habitat. By disabling all or pairs of the spiders' eight eyes we found that homing ability was severely reduced when vision was fully abolished. Vision, therefore, seems to play a key role in the nocturnal navigational performances of L. Arenicola . After excluding two or three pairs of eyes, the spiders were found to be able to navigate successfully using only their lateral eyes or only their anterior median eyes. Measurement of the eyes' visual fields showed that the secondary eyes combined have a near full (panoramic) view of the surroundings. The visual fields of the principal eyes overlap almost completely with those of the anterior lateral eyes. Electroretinogram recordings indicate that each eye type contains a single photopigment with sensitivity peaking at ∼525 nm in the posterior and anteriomedian eyes, and at ∼540 nm in the anteriolateral eyes. Theoretical calculations of photon catches showed that the eyes are likely to employ a combination of spatial and temporal pooling in order to function at night. Under starlit conditions, the raw spatial and temporal resolution of the eyes is insufficient for detecting any visual information on structures in the landscape, and bright stars would be the only objects visible to the spiders. However, by summation in space and time, the spiders can rescue enough vision to detect coarse landscape structures. We show that L. Arenicola spiders are likely to be using temporal summation to navigate at night.
Daneric Nilsson - One of the best experts on this subject based on the ideXlab platform.
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Vision in the nocturnal wandering spider Leucorchestris Arenicola (Araneae: Sparassidae).
The Journal of experimental biology, 2020Co-Authors: Thomas Norgaard, Daneric Nilsson, Joh R Henschel, Anders Garm, Rudiger WehnerAbstract:At night the Namib Desert spider Leucorchestris Arenicola performs long-distance homing across its sand dune habitat. By disabling all or pairs of the spiders' eight eyes we found that homing ability was severely reduced when vision was fully abolished. Vision, therefore, seems to play a key role in the nocturnal navigational performances of L. Arenicola. After excluding two or three pairs of eyes, the spiders were found to be able to navigate successfully using only their lateral eyes or only their anterior median eyes. Measurement of the eyes' visual fields showed that the secondary eyes combined have a near full (panoramic) view of the surroundings. The visual fields of the principal eyes overlap almost completely with those of the anterior lateral eyes. Electroretinogram recordings indicate that each eye type contains a single photopigment with sensitivity peaking at approximately 525 nm in the posterior and anteriomedian eyes, and at approximately 540 nm in the anteriolateral eyes. Theoretical calculations of photon catches showed that the eyes are likely to employ a combination of spatial and temporal pooling in order to function at night. Under starlit conditions, the raw spatial and temporal resolution of the eyes is insufficient for detecting any visual information on structures in the landscape, and bright stars would be the only objects visible to the spiders. However, by summation in space and time, the spiders can rescue enough vision to detect coarse landscape structures. We show that L. Arenicola spiders are likely to be using temporal summation to navigate at night.
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vision in the nocturnal wandering spider leucorchestris Arenicola araneae sparassidae
The Journal of Experimental Biology, 2008Co-Authors: Thomas Norgaard, Daneric Nilsson, Joh R Henschel, Anders Garm, Rudiger WehnerAbstract:At night the Namib Desert spider Leucorchestris Arenicola performs long-distance homing across its sand dune habitat. By disabling all or pairs of the spiders' eight eyes we found that homing ability was severely reduced when vision was fully abolished. Vision, therefore, seems to play a key role in the nocturnal navigational performances of L. Arenicola . After excluding two or three pairs of eyes, the spiders were found to be able to navigate successfully using only their lateral eyes or only their anterior median eyes. Measurement of the eyes' visual fields showed that the secondary eyes combined have a near full (panoramic) view of the surroundings. The visual fields of the principal eyes overlap almost completely with those of the anterior lateral eyes. Electroretinogram recordings indicate that each eye type contains a single photopigment with sensitivity peaking at ∼525 nm in the posterior and anteriomedian eyes, and at ∼540 nm in the anteriolateral eyes. Theoretical calculations of photon catches showed that the eyes are likely to employ a combination of spatial and temporal pooling in order to function at night. Under starlit conditions, the raw spatial and temporal resolution of the eyes is insufficient for detecting any visual information on structures in the landscape, and bright stars would be the only objects visible to the spiders. However, by summation in space and time, the spiders can rescue enough vision to detect coarse landscape structures. We show that L. Arenicola spiders are likely to be using temporal summation to navigate at night.