scholarly journals Outsourced hearing in spiders by using their webs as auditory sensors

2021 ◽  
Author(s):  
Jian Zhou ◽  
Junpeng Lai ◽  
Gil Menda ◽  
Jay A. Stafstrom ◽  
Carol I. Miles ◽  
...  

Hearing is a fundamental sense of many animals, including all mammals, birds, some reptiles, amphibians, fish and arthropods1,2. The auditory organs of these animals are extremely diverse in anatomy after hundreds of millions of years of evolution3-5, yet all are made up of cellular tissue and are embodied meaning that its functional anatomy is constrained by developmental morphogenesis. Here we show hearing in the orb-weaving spider, Larinioides sclopetarius is not constrained by embodiment but is extended through outsourcing hearing to its proteinaceous, self-manufactured orb-web, and hence under behavioral control, not developmental biology. We find the wispy, wheel-shaped orb-web acts as a hyperacute acoustic array to capture the sound-induced air particle movements that approach the maximum physical efficiency, better than the acoustic responsivity of all previously known ears6,7. By manipulating the web threads with its eight vibration-sensitive legs8-10, the spider remotely detects and localizes the source of an incoming airborne acoustic wave emitted by approaching prey or predators. By outsourcing its acoustic sensors to its web, the spider is released from embodied morphogenetic constraints and permits the araneid spider to increase its sound-sensitive surface area enormously, up to 10,000 times greater than the spider itself11. The use of the web also enables a spider the flexibility to functionally adjust and regularly regenerate its 'external ear' according to its needs. This finding opens a new perspective on animal hearing - the 'outsourcing' and 'supersizing' of auditory function in a spider, one of the earliest animals to live on land12. The novel hearing mechanism provides unique features for studying extended and regenerative sensing13-15, and designing novel acoustic flow detectors for precise fluid dynamic measurement and manipulation16-18.

2018 ◽  
Vol 12 (2) ◽  
pp. 260-278
Author(s):  
Christoph Demmerling

Abstract The following article argues that fictional texts can be distinguished from non-fictional texts in a prototypical way, even if the concept of the fictional cannot be defined in classical terms. In order to be able to characterize fictional texts, semantic, pragmatic, and reader-conditioned factors have to be taken into account. With reference to Frege, Searle, and Gabriel, the article recalls some proposals for how we might define fictional speech. Underscored in particular is the role of reception for the classification of a text as fictional. I make the case, from a philosophical perspective, for the view that fictional texts represent worlds that do not exist even though these worlds obviously can, and de facto do, contain many elements that are familiar to us from our world. I call these worlds reading worlds and explain the relationship between reading worlds and the life world of readers. This will help support the argument that the encounter with fictional literature can invoke real feelings and that such feelings are by no means irrational, as some defenders of the paradox of fiction would like us to believe. It is the exemplary character of fictional texts that enables us to make connections between the reading worlds and the life world. First and foremost, the article discusses the question of what it is that readers’ feelings are in fact related to. The widespread view that these feelings are primarily related to the characters or events represented in a text proves too simple and needs to be amended. Whoever is sad because of the fate of a fictive character imagines how he or she would fare if in a similar situation. He or she would feel sad as it relates to his or her own situation. And it is this feeling on behalf of one’s self that is the presupposition of sympathy for a fictive character. While reading, the feelings related to fictive characters and content are intertwined with the feelings related to one’s own personal concerns. The feelings one has on his or her own behalf belong to the feelings related to fictive characters; the former are the presupposition of the latter. If we look at the matter in this way, a new perspective opens up on the paradox of fiction. Generally speaking, the discussion surrounding the paradox of fiction is really about readers’ feelings as they relate to fictive persons or content. The question is then how it is possible to have them, since fictive persons and situations do not exist. If, however, the emotional relation to fictive characters and situations is conceived of as mediated by the feelings one has on one’s own behalf, the paradox loses its confusing effect since the imputation of existence no longer plays a central role. Instead, the conjecture that the events in a fictional story could have happened in one’s own life is important. The reader imagines that a story had or could have happened to him or herself. Readers are therefore often moved by a fictive event because they relate what happened in a story to themselves. They have understood the literary event as something that is humanly relevant in a general sense, and they see it as exemplary for human life as such. This is the decisive factor which gives rise to a connection between fiction and reality. The emotional relation to fictive characters happens on the basis of emotions that we would have for our own sake were we confronted with an occurrence like the one being narrated. What happens to the characters in a fictional text could also happen to readers. This is enough to stimulate corresponding feelings. We neither have to assume the existence of fictive characters nor do we have to suspend our knowledge about the fictive character of events or take part in a game of make-believe. But we do have to be able to regard the events in a fictional text as exemplary for human life. The representation of an occurrence in a novel exhibits a number of commonalities with the representation of something that could happen in the future. Consciousness of the future would seem to be a presupposition for developing feelings for something that is only represented. This requires the power of imagination. One has to be able to imagine what is happening to the characters involved in the occurrence being narrated in a fictional text, ›empathize‹ with them, and ultimately one has to be able to imagine that he or she could also be entangled in the same event and what it would be like. Without the use of these skills, it would remain a mystery how reading a fictional text can lead to feelings and how fictive occurrences can be related to reality. The fate of Anna Karenina can move us, we can sympathize with her, because reading the novel confronts us with possibilities that could affect our own lives. The imagination of such possibilities stimulates feelings that are related to us and to our lives. On that basis, we can participate in the fate of fictive characters without having to imagine that they really exist.


Author(s):  
Ariska Puspita Anggraini ◽  

The phenomenon of sex has always been novel in every era. In Indonesia, for example, Enny Arrow’s stencil novel has been circulating, which has been named as a legend of Indonesian erotic literature. Along with the development of technology, the existence of stencil novels was replaced by DVDs or VCDs, which then continued with the emergence of various sites providing access to pornography. This difference in phenomena certainly makes the meaning of sex for each individual different. This research will analyze the meaning of sex in the stencil novel by Enny Arrow in the eyes of millennial men. The data analysis will focus on social psychological factors using Normand Holland’s literary reception theory. From the data analysis, it can be concluded that there are different views on sexual relations before and after reading the novel. This research is expected to provide a new perspective on the picture of sexuality for modern humans.


2021 ◽  
Vol 3 ◽  
pp. ec03015
Author(s):  
Keizo Takasuka

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.


2021 ◽  
pp. 231-236
Author(s):  
Bill Bell

The epilogue rounds off the argument by returning to Crusoe as a paradigm of the act of reading in the British empire. In the hands of different readers not even Robinson Crusoe was as straightforward as it seemed. Despite the fact that the novel has often been read as a manual for empire, it is far more complex than some commentaries would have us believe. Similar ambivalences apply to the lives and minds of many overseas British in the long nineteenth century. While the early twentieth century is commonly thought to have embodied a decline in imperial values, the reading habits of colonial subjects throughout the period would seem to indicate that imperial assurances were less robust than official sources would seem to suggest. The five reading constituencies that are described in the foregoing chapters, all of them in different ways operating within the web of empire, were ones in which individuals often found imperial confidence in its own mission wanting, something that was time and again demonstrated through in their acts of reading.


2017 ◽  
Vol 51 (4) ◽  
pp. 12-22 ◽  
Author(s):  
Xiuyan Liu ◽  
Xin Luan ◽  
Z. Daniel Deng ◽  
Dalei Song ◽  
Shengbo Zang ◽  
...  

AbstractAn autonomous Moored Reciprocating Vertical Profiler (MRVP) has been developed and tested for measuring ocean turbulence. The MRVP is designed to combine the advantages of long-term moored measurements at specified depths with those of short-term ship-supported continuous profiling performed at high vertical resolution. The profiler is programmed to repeat vertical motions autonomously along the mooring cable based on a buoyancy-driven mechanism. A sea trial has been conducted in the South China Sea to evaluate the performance of the profiler. The shear probe data are unreliable when the flow past sensors is not sufficiently greater than an estimate of turbulent velocity. For 65% of the dataset, turbulence measurements are of high quality and the magnitude of dissipation rates is up to O(10−10) W kg−1. To minimize the contamination induced by instrument vibration and improve the estimation of turbulent kinetic energy terms, an advanced cross-spectrum algorithm is implemented to the measured shear data. The corrected spectra agreed well with the empirical Nasmyth spectrum, and dissipation rates had averagely decreased a factor of 2 and 8 times lower than the raw spectra. The autonomous MRVP is proven to be a stable platform, and the novel upward measurement provides a new perspective for measuring long-term time series of turbulence mixing.


2019 ◽  
Vol 59 (6) ◽  
pp. 1636-1645 ◽  
Author(s):  
B Mortimer

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.


2020 ◽  
Vol 108 (1) ◽  
Author(s):  
Samuel Zschokke ◽  
Stefanie Countryman ◽  
Paula E. Cushing

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.


Behaviour ◽  
2008 ◽  
Vol 145 (3) ◽  
pp. 277-295 ◽  
Author(s):  
Felipe Gawryszewski ◽  
Paulo Motta

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.


2019 ◽  
Vol 16 (154) ◽  
pp. 20190201 ◽  
Author(s):  
B. Mortimer ◽  
A. Soler ◽  
L. Wilkins ◽  
F. Vollrath

A spider's web is a multifunctional structure that captures prey and provides an information platform that transmits vibrational information. Many physical factors interact to influence web vibration and information content, from vibration source properties and input location, to web physical properties and geometry. The aim of the study was to test whether orb web vibration contains information about the location of the source of vibration. We used finite-element analysis model webs to control and vary major physical factors, investigating webs where spiders use a direct or remote monitoring strategy. When monitoring with eight sensors (legs) at the web centre, a comparison of longitudinal and transverse wave amplitude between the sensors gave sufficient information to determine source direction and distance, respectively. These localization cues were robust to changes in source amplitude, input angle and location, with increased accuracy at lower source amplitudes. When remotely monitoring the web using a single thread connected to the web's hub (a signal thread), we found that locational information was not available when the angle of the source input was unknown. Furthermore, a free sector and a stiff hub were physical mechanisms to aid information transfer, which provides insights for bioinspired fibre networks for sensing technologies.


2002 ◽  
Vol 357 (1418) ◽  
pp. 155-163 ◽  
Author(s):  
D. P. Knight ◽  
F. Vollrath

Liquid crystal elastomers (LCEs) have recently been described as a new class of matter. Here we review the evidence for the novel conclusion that the fibrillar collagens and the dragline silks of orb web spiders belong to this remarkable class of materials. Unlike conventional rubbers, LCEs are ordered, rather than disordered, at rest. The identification of these biopolymers as LCEs may have a predictive value. It may explain how collagens and spider dragline silks are assembled. It may provide a detailed explanation for their mechanical properties, accounting for the variation between different members of the collagen family and between the draglines in different spider species. It may provide a basis for the design of biomimetic collagen and dragline silk analogues by genetic engineering, peptide- or classical polymer synthesis. Biological LCEs may exhibit a range of exotic properties already identified in other members of this remarkable class of materials. In this paper, the possibility that other transversely banded fibrillar proteins are also LCEs is discussed.


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