scholarly journals Functional flexibility in a spider's orb web

2020 ◽  
Vol 223 (23) ◽  
pp. jeb234070
Author(s):  
Tom Mulder ◽  
Beth Mortimer ◽  
Fritz Vollrath
Keyword(s):  
Reaction Times ◽  
Fruit Fly ◽  
Initial Reaction ◽  
Common Occurrence ◽  
Functional Flexibility ◽  
Prey Identification ◽  
In The Wild ◽  
Orb Web ◽  
The Web ◽  
Do So

ABSTRACTWeb spiders rely on vibrations propagated via their web to identify, locate and capture entangled prey. Here, we experimentally tested the robustness of the orb weaver's predation strategy when webs are severely distorted and silk tensions are drastically altered throughout the web, a common occurrence in the wild. We assessed prey identification efficiency by comparing the spider's initial reaction times towards a fruit fly trapped in the web, we measured location efficiency by comparing times and number of tugging bouts performed, and we determined capture efficiency by comparing capture times. It emerged that spiders are capable of identifying, locating and capturing prey in distorted webs, albeit taking somewhat longer to do so.

Prey-capture strategies in sympatric web-building spiders

2006 ◽  
Vol 84 (7) ◽  
pp. 964-973 ◽  
Author(s):  
Samuel Zschokke ◽  
Yann Hénaut ◽  
Suresh P. Benjamin ◽  
J. Alvaro García-Ballinas
Keyword(s):  
Field Experiment ◽  
Prey Capture ◽  
Reaction Times ◽  
Maintenance Costs ◽  
Trade Off ◽  
Orb Web ◽  
Web Building ◽  
The Web

Arthropods in several orders use traps to capture prey. Such trap-building predators expend most of their foraging energy prior to any prey contact. Nevertheless, relative investments in trap construction and actual prey capture may vary among trap builders, and they are likely to face a trade-off between building very effective but energetically costly traps and building less effective traps requiring faster reaction times when attacking prey. We analysed this trade-off in a field experiment by comparing the prey capture behaviour of four different sympatric web-building spiders (Araneae: Araneidae, Nephilidae, Tetragnathidae, Theridiidae) with the retention times of five different prey types in the webs of these spiders. Retention times differed greatly among webs and among prey types. The vertical orb webs retained prey longer than the horizontal orb web and the sheet web, and active prey escaped more quickly than less active prey. Among spiders with orb webs, the spider with the web that retained prey for the shortest time was the fastest to capture prey, thus confirming the expected trade-off between building long-retaining webs and attacking slowly versus building short-retaining webs and attacking more rapidly. The sheet web, however, neither retained prey for an appreciable period of time nor facilitated rapid prey capture. We suggest that this low capture effectiveness of sheet webs is compensated by their lower maintenance costs.

New Caledonian crows show behavioural flexibility when manufacturing their tools

Behaviour ◽  
2017 ◽  
Vol 154 (1) ◽  
pp. 65-91 ◽  
Author(s):  
Brenna Knaebe ◽  
Alex H. Taylor ◽  
Douglas M. Elliffe ◽  
Russell D. Gray
Keyword(s):  
Behavioural Flexibility ◽  
Tool Manufacture ◽  
In The Wild ◽  
New Caledonian Crows ◽  
Do So

New Caledonian crows have demonstrated flexible behaviour when using tools and solving novel problems. However, we do not know whether this flexibility extends to tool manufacture. Here, we show that these crows respond to different tool-using problems by altering the length of the tools that they manufacture; on average, crows made shorter tools for tasks requiring short tools and longer tools for tasks requiring long tools. They continued to do so when they could not simultaneously see the tool-manufacturing material and the apparatus requiring the use of a tool. Despite altering the length of their tools, the crows frequently did not make tools short or long enough to reliably extract the bait, though this may have been due to shortcomings in the task presented to them. Our results demonstrate that these crows have a degree of behavioural flexibility when making tools, which may be used in the wild during foraging.

scholarly journals Attention and the motion after effect: New measurements with visual search reveal important individual differences in adaptability

2018 ◽  
Author(s):  
Michael J. Morgan ◽  
Joshua A. Solomon
Keyword(s):  
Reaction Times ◽  
Visual Pathway ◽  
Human Vision ◽  
The Other ◽  
Test Array ◽  
Mouse Click ◽  
Search Speed ◽  
After Effect ◽  
The One ◽  
Do So

AbstractIt is usually assumed that sensory adaptation is a universal property of human vision. However, in two experiments designed to measure adaptation without bias, we have discovered a minority of participants who were unusual in the extent of their adaptation to motion. One experiment was designed so that targets would be invisible without adaptation; the other, so that adaptation would interfere with target detection. In the first, participants adapted to a spatial array of moving Gabor patches. On each trial the adapting array was followed by a test array in which but all of the test patches except one were identical to their spatially corresponding adaptors; the target moved in the opposite direction to its adaptor. Participants were required to identify the location of the changed target with a mouse click. The ability to do so increased with the number of adapting trials. Neither search speed nor accuracy was affected by an attentionally-demanding conjunction task at the fixation point during adaptation, suggesting low-level (pre-attentive) sites in the visual pathway for the adaptation. However, a minority of participants found the task virtually impossible. In the second experiment the same participants were required to identify the one element in the test array that was slowly moving: reaction times in this case were elevated following adaptation. The putatively weak adapters from the first experiment found this task easier than the strong adapters.

scholarly journals Biological control of fruit flies: bibliometric analysis on the main biocontrol agents

2021 ◽  
Vol 10 (1) ◽  
pp. e22510111245
Author(s):  
Angélica da Silva Salustino ◽  
Wilma Freitas Celedônio ◽  
Manoel Cícero de Oliveira Filho ◽  
Demichaelmax Sales de Melo ◽  
Josué José da Silva ◽  
...  
Keyword(s):  
Biological Control ◽  
Bibliometric Analysis ◽  
Web Of Science ◽  
Fruit Fly ◽  
Fruit Trees ◽  
Fruit Flies ◽  
Biological Agents ◽  
Scientific Field ◽  
Publication Language ◽  
The Web

The Tephritidae family has many fruit fly species responsible for causing direct and indirect damage to economically important fruit trees worldwide. Biological control has been sought as a method for the management of these insects, mainly because it does not cause adverse damage to the environment. Thus, this review sought information on what is currently being published in the scientific field about the main biological agents that are used to control fruit flies. The information was obtained through surveys between the months of June and August 2020, in bases such as the Web of Science, Scopus, ScienceDirect, Taylor & Francis, Springer, and Scielo. The inclusion of the articles followed criteria such as publication language English, Portuguese and Spanish, available in full, from categories A1 to B1, related to the biological agents used in the control of fruit flies and published in the last five years. A total of 2,362 studies were found, of which 105 articles were selected for this review. Regarding the years of publication, only 27% of the studies correspond to references from the years 2019 and 2020, with a greater number of research on parasitoids and developed in the laboratory. The largest concentration of research was in countries like Brazil, Mexico, and Spain.

The northernmost record of Eriostethus rufus (Uchida, 1932) (Hymenoptera, Ichneumonidae) with an indication of new host, Trichonephila clavata (Koch, 1878) (Araneae, Araneidae) and its web manipulation

2021 ◽  
Vol 3 ◽  
pp. ec03015
Author(s):  
Keizo Takasuka
Keyword(s):  
Dna Barcoding ◽  
New Host ◽  
Web Structure ◽  
Inverted Triangle ◽  
Orb Web ◽  
The Web ◽  
Northern Japan

Eriostethus rufus (Uchida, 1932) is a polysphinctine ectoparasitoid of araneid spiders (Neoscona spp.) and is endemic to Japan. An individual was collected in Yamagata Prefecture (38º46' N), northern Japan, the northernmost record of the species and also the genus. Its identification was confirmed by morphology and by DNA barcoding. The cocoon was found in a large modified web, which is unique in that the web structure is shaped like an inverted triangle extending to over 50 cm with the cocoon hanging from an ill-defined part of the cocoon web without any organized structure surrounding the cocoon. The host spider of this individual appears to be Trichonephila clavata (Koch, 1878) (Araneidae, Nephilinae) based on several circumstantial evidences. The structure of the modified web suggests that the pre-existing web was partly reused, the orb web was completely removed, and sustaining threads of the barrier web would be newly moored to the substrates. This record means that E. rufus parasitises host spiders of two subfamilies, which is unusual for the group.

The Semantic Web

2008 ◽  
pp. 505-511
Author(s):  
Kevin Curran ◽  
Gary Gumbleton
Keyword(s):  
World Wide Web ◽  
Semantic Web ◽  
World Wide ◽  
Software Agents ◽  
Web Pages ◽  
The World ◽  
The Web ◽  
Do So

Tim Berners-Lee, director of the World Wide Web Consortium (W3C), states that, “The Semantic Web is not a separate Web but an extension of the current one, in which information is given well-defined meaning, better enabling computers and people to work in cooperation” (Berners-Lee, 2001). The Semantic Web will bring structure to the meaningful content of Web pages, creating an environment where software agents, roaming from page to page, can readily carry out sophisticated tasks for users. The Semantic Web (SW) is a vision of the Web where information is more efficiently linked up in such a way that machines can more easily process it. It is generating interest not just because Tim Berners-Lee is advocating it, but because it aims to solve the problem of information being hidden away in HTML documents, which are easy for humans to get information out of but are difficult for machines to do so. We will discuss the Semantic Web here.

A Spider’s Vibration Landscape: Adaptations to Promote Vibrational Information Transfer in Orb Webs

2019 ◽  
Vol 59 (6) ◽  
pp. 1636-1645 ◽  
Author(s):  
B Mortimer
Keyword(s):  
Information Transfer ◽  
Low Frequencies ◽  
Silk Fibers ◽  
Physical Constraints ◽  
Vibration Sensors ◽  
Sensitivity Pattern ◽  
Orb Web ◽  
Speed Of Propagation ◽  
The Web

Abstract Spider orb webs are used not only for catching prey, but also for transmitting vibrational information to the spider. Vibrational information propagates from biological sources, such as potential prey or mates, but also abiotic sources, such as wind. Like other animals, the spider must cope with physical constraints acting on the propagation of vibrational information along surfaces and through materials—including loss of energy, distortion, and filtering. The spider mitigates these physical constraints by making its orb web from up to five different types of silks, closely controlling silk use and properties during web building. In particular, control of web geometry, silk tension, and silk stiffness allows spiders to adjust how vibrations spread throughout the web, as well as their amplitude and speed of propagation, which directly influences energy loss, distortion, and filtering. Turning to how spiders use this information, spiders use lyriform organs distributed across their eight legs as vibration sensors. Spiders can adjust coupling to the silk fibers and use posture to modify vibrational information as it moves from the web to the sensors. Spiders do not sense all vibrations equally—they are least sensitive to low frequencies (<30 Hz) and most sensitive to high frequencies (ca. 1 kHz). This sensitivity pattern cannot be explained purely by the frequency range of biological inputs. The role of physical and evolutionary constraints is discussed to explain spider vibration sensitivity and a role of vibration sensors to detect objects on the web as a form of echolocation is also discussed.

scholarly journals Spiders in space—orb-web-related behaviour in zero gravity

2020 ◽  
Vol 108 (1) ◽  
Author(s):  
Samuel Zschokke ◽  
Stefanie Countryman ◽  
Paula E. Cushing
Keyword(s):  
International Space Station ◽  
Space Station ◽  
Zero Gravity ◽  
Random Orientation ◽  
Natural Conditions ◽  
International Space ◽  
Orb Web ◽  
Web Building ◽  
The Web

AbstractGravity is very important for many organisms, including web-building spiders. Probably the best approach to study the relevance of gravity on organisms is to bring them to the International Space Station. Here, we describe the results of such an experiment where two juvenile Trichonephila clavipes (L.) (Araneae, Nephilidae) spiders were observed over a 2-month period in zero gravity and two control spiders under otherwise identical conditions on Earth. During that time, the spiders and their webs were photographed every 5 min. Under natural conditions, Trichonephila spiders build asymmetric webs with the hub near the upper edge of the web, and they always orient themselves downwards when sitting on the hub whilst waiting for prey. As these asymmetries are considered to be linked to gravity, we expected the spiders experiencing no gravity to build symmetric webs and to show a random orientation when sitting on the hub. We found that most, but not all, webs built in zero gravity were indeed quite symmetric. Closer analysis revealed that webs built when the lights were on were more asymmetric (with the hub near the lights) than webs built when the lights were off. In addition, spiders showed a random orientation when the lights were off but faced away from the lights when they were on. We conclude that in the absence of gravity, the direction of light can serve as an orientation guide for spiders during web building and when waiting for prey on the hub.

The silk tuft web decorations of the orb-weaver Gasteracantha cancriformis : testing the prey attraction and the web advertisement hypotheses

Behaviour ◽  
2008 ◽  
Vol 145 (3) ◽  
pp. 277-295 ◽  
Author(s):  
Felipe Gawryszewski ◽  
Paulo Motta
Keyword(s):  
Drosophila Melanogaster ◽  
Foraging Success ◽  
Uv Reflectance ◽  
Web Advertisement ◽  
Orb Web ◽  
Orb Web Spiders ◽  
Large Animals ◽  
And Control ◽  
The Web ◽  
Prey Attraction

AbstractSeveral orb-web spiders build conspicuous decorations in their webs. The prey attraction hypothesis proposes that decorations increase spider foraging success by attracting prey, and that attraction is linked to UV reflectance. Alternatively, the web advertisement hypothesis proposes that decorations are a signal that advertises the presence of the web to large animals. We tested both hypotheses for the web silk tufts of Gasteracantha cancriformis. Even though tufts are UV reflective, we did not find support for the prey attraction hypothesis. In the field, when webs with tufts painted black and control webs were compared, there were no differences in the number of prey captured, number of damaged areas in webs and type of prey captured. In the laboratory, Drosophila melanogaster did not demonstrate preference for tufted silk lines versus non-tufted silk lines. Our data also did not give support for the web advertisement hypothesis. The proportion of web destruction was similar between web with tufts painted black and control webs during four days of experimentation. Therefore, two of the most favoured hypotheses that attempt to explain decorations do not apply for web silk tufts in our study system. Instead we propose that silk tufts might be an aposematic signal.

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