Attention focusing in a sit-and-wait forager: a spider controls its prey-detection ability in different web sectors by adjusting thread tension

Nakata, Kensuke

doi:10.1098/rspb.2009.1583

Cited by 38 publications

(33 citation statements)

References 18 publications

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“…Animals spatially focus their attention toward prey for suitable foraging (5,6). During prey pursuit, most animals direct their visual attention toward it [e.g., tiger beetle (7), dragonfly (8), and falcon (9)].…”

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confidence: 99%

Echolocating bats use future-target information for optimal foraging

Fujioka

Aihara

Sumiya

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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When seeing or listening to an object, we aim our attention toward it. While capturing prey, many animal species focus their visual or acoustic attention toward the prey. However, for multiple prey items, the direction and timing of attention for effective foraging remain unknown. In this study, we adopted both experimental and mathematical methodology with microphone-array measurements and mathematical modeling analysis to quantify the attention of echolocating bats that were repeatedly capturing airborne insects in the field. Here we show that bats select rational flight paths to consecutively capture multiple prey items. Microphone-array measurements showed that bats direct their sonar attention not only to the immediate prey but also to the next prey. In addition, we found that a bat's attention in terms of its flight also aims toward the next prey even when approaching the immediate prey. Numerical simulations revealed a possibility that bats shift their flight attention to control suitable flight paths for consecutive capture. When a bat only aims its flight attention toward its immediate prey, it rarely succeeds in capturing the next prey. These findings indicate that bats gain increased benefit by distributing their attention among multiple targets and planning the future flight path based on additional information of the next prey. These experimental and mathematical studies allowed us to observe the process of decision making by bats during their natural flight dynamics.bat sonar | aerial capture | microphone array | mathematical modeling | flight dynamics S electively focusing attention on a particular target allows us to effectively extract information (1-4). Animals spatially focus their attention toward prey for suitable foraging (5, 6). During prey pursuit, most animals direct their visual attention toward it [e.g., tiger beetle (7), dragonfly (8), and falcon (9)]. Specifically, for example, dragonflies maintain a prey item at a constant retinal position during approaching it so that they steer an interception flight path (interception strategy) (10). However, for multiple prey items, the direction and timing of attention for effective foraging remain unknown.Echolocating bats actively emit sonar signals to obtain surrounding information and adaptively change the characteristics of the emissions depending on the situation (11). Therefore, their attention in terms of the sonar (sonar attention) is characterized as the direction to which bats emit their sonar beams (12-14). When echolocating bats approach an airborne insect, the sonar attention directs toward the prey (12, 13). During natural foraging, the sonar attention of bats alternately shifts from their flying direction to the side (15). Additionally the wild bats are capable of capturing two prey items within the short interval of 1 s (16).We predicted that bats localize multiple prey items by distributing their attention between them and then select an efficient flight path to successively capture the multiple prey. To test this prediction, ...

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confidence: 99%

Echolocating bats use future-target information for optimal foraging

Fujioka

Aihara

Sumiya

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…Even after that, they sometimes paused on the way to the prey to jerk radial threads again. To assess the running speed, such pauses were excluded from the time needed for spiders to reach the prey, because we wanted to exclude the possible effect of directional difference in the efficiency for spiders to locate the prey (Nakata 2010). To do this, we determined the vertical position of the spider's head in every frame of the video and calculated its distance between two consecutive frames from the start of running to the first touch on the prey.…”

Section: Methodsmentioning

confidence: 99%

Upside-down spiders build upside-down orb webs: web asymmetry, spider orientation and running speed in Cyclosa

Nakata

Zschokke

2010

Proc. R. Soc. B.

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Almost all spiders building vertical orb webs face downwards when sitting on the hubs of their webs, and their webs exhibit an up -down size asymmetry, with the lower part of the capture area being larger than the upper. However, spiders of the genus Cyclosa, which all build vertical orb webs, exhibit inter-and intraspecific variation in orientation. In particular, Cyclosa ginnaga and C. argenteoalba always face upwards, and C. octotuberculata always face downwards, whereas some C. confusa face upwards and others face downwards or even sideways. These spiders provide a unique opportunity to examine why most spiders face downwards and have asymmetrical webs. We found that upward-facing spiders had upside-down webs with larger upper parts, downward-facing spiders had normal webs with larger lower parts and sideways-facing spiders had more symmetrical webs. Downward-facing C. confusa spiders were larger than upward-and sideways-facing individuals. We also found that during prey attacks, downward-facing spiders ran significantly faster downwards than upwards, which was not the case in upwardfacing spiders. These results suggest that the spider's orientation at the hub and web asymmetry enhance its foraging efficiency by minimizing the time to reach prey trapped in the web.

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“…In debris decoration, prey remnants and spider's own moulted exoskeletons are arranged in a vertical line [4]. Adult females with debris decorations were collected at Mt.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Spiders are more sensitive to prey on the web when thread tension is increased [4,5]. Recent studies have provided evidences for the hypothesis that some orb-web spiders actively regulate thread tension to enhance the transmission capacity of vibration signals from prey [4,5]. Cyclosa octotuberculata is an example; the spider pulls the radial threads of the web and hence increases thread tension when it waits for prey, and thread pulling is stronger in vertical than in horizontal web sectors [4].…”

Section: Introductionmentioning

confidence: 99%

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Spatial learning affects thread tension control in orb-web spiders

Nakata

2013

Biol. Lett.

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Although it is well known that spatial learning can be important in the biology of predators that actively move around in search for food, comparatively little is known about ways in which spatial learning might function in the strategies of sit-and-wait predators. In this study, Cyclosa octotuberculata, an orb-web spider that uses its legs to contract radial threads of its web to increase thread tension, was trained to capture prey in limited web sectors. After training, spiders that had captured prey in horizontal web sectors applied more tension on radial threads connected to horizontal sectors than spiders that had captured prey in vertical sectors. This result suggests that the effect of experience on C. octotuberculata's behaviour is not expressed in the way the trained spider responds to prey-derived stimuli and is instead expressed in behaviour by which the spider anticipates the likely direction from which prey will arrive in the future. This illustrates that learning can be important even when the predator remains in one location during foraging bouts.

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Attention focusing in a sit-and-wait forager: a spider controls its prey-detection ability in different web sectors by adjusting thread tension

Cited by 38 publications

References 18 publications

Echolocating bats use future-target information for optimal foraging

Echolocating bats use future-target information for optimal foraging

Upside-down spiders build upside-down orb webs: web asymmetry, spider orientation and running speed in Cyclosa

Spatial learning affects thread tension control in orb-web spiders

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