scholarly journals Lack of neophobic responses to color in a jumping spider that uses color cues when foraging (Habronattus pyrrithrix)

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254865
Author(s):  
Michael E. Vickers ◽  
Madison L. Heisey ◽  
Lisa A. Taylor

Chemically defended prey often advertise their toxins with bright and conspicuous colors. To understand why such colors are effective at reducing predation, we need to understand the psychology of key predators. In bird predators, there is evidence that individuals avoid novelty—including prey of novel colors (with which they have had no prior experience). Moreover, the effect of novelty is sometimes strongest for colors that are typically associated with aposematic prey (e.g., red, orange, yellow). Given these findings in the bird literature, color neophobia has been argued to be a driving force in the evolution of aposematism. However, no studies have yet asked whether invertebrate predators respond similarly to novel colors. Here, we tested whether naive lab-raised jumping spiders (Habronattus pyrrithrix) exhibit similar patterns of color neophobia to birds. Using color-manipulated living prey, we first color-exposed spiders to prey of two out of three colors (blue, green, or red), with the third color remaining novel. After this color exposure phase, we gave the spiders tests where they could choose between all three colors (two familiar, one novel). We found that H. pyrrithrix attacked novel and familiar-colored prey at equal rates with no evidence that the degree of neophobia varied by color. Moreover, we found no evidence that either prey novelty nor color (nor their interaction) had an effect on how quickly prey was attacked. We discuss these findings in the context of what is known about color neophobia in other animals and how this contributes to our understanding of aposematic signals.

2010 ◽  
Vol 278 (1710) ◽  
pp. 1356-1364 ◽  
Author(s):  
Jin-Nan Huang ◽  
Ren-Chung Cheng ◽  
Daiqin Li ◽  
I-Min Tso

Many spiders possess myrmecomorphy, and species of the jumping spider genus Myrmarachne exhibit nearly perfect ant mimicry. Most salticids are diurnal predators with unusually high visual acuity that prey on various arthropods, including conspecifics. In this study, we tested whether predation pressure from large jumping spiders is one possible driving force of perfect ant mimicry in jumping spiders. The results showed that small non-ant-mimicking jumping spiders were readily treated as prey by large ones (no matter whether heterospecific or conspecific) and suffered high attack and mortality rates. The size difference between small and large jumping spiders significantly affected the outcomes of predatory interactions between them: the smaller the juvenile jumping spiders, the higher the predation risk from large ones. The attack and mortality rates of ant-mimicking jumping spiders were significantly lower than those of non-ant-mimicking jumping spiders, indicating that a resemblance to ants could provide protection against salticid predation. However, results of multivariate behavioural analyses showed that the responses of large jumping spiders to ants and ant-mimicking salticids differed significantly. Results of this study indicate that predation pressure from large jumping spiders might be one selection force driving the evolution of nearly perfect myrmecomorphy in spiders and other arthropods.


Author(s):  
Wilfried Wunderlich ◽  
Janos Lendvai ◽  
Hans-Joachim Gudladt

This article describes concepts of three features of microstructure–properties relationship, first the imaging and formation of nano-particles, then their contribution to hardness, and finally hydrogen embrittlement during fatigue. First, we briefly review the imaging modes in transmission electron microscopy (TEM) for nano-sized precipitates. The next issue is the hardening in Aluminum alloys, which is caused by GP-zones or precipitates, formed at the second step of the annealing process. After homogenization, the peak-hardness can be generally achieved by a few hours of annealing between 120°C and 200°C. Hardness measurements and equal-channel axial pressing (ECAP) showed that even at room temperature the driving force for formation of the particles is so strong that already within one hour of annealing after homogenization a remarkable hardening occurs. The third issue, hydrogen embrittlement, is caused by oxidation of pure Al surfaces produced at the crack tip during fatigue under ambient or wet moisture conditions. The cracks propagate preferentially along the precipitation free zone adjacent to grain boundaries, where hydrogen diffusion is fastest.


2020 ◽  
Vol 96 (1) ◽  
pp. 73-90
Author(s):  
Renner Luiz Cerqueira Baptista ◽  
Pedro de Souza Castanheira ◽  
Gabriel Assunção Oliveira ◽  
André Wanderley do Prado

New data on the jumping-spider genus Arnoliseus are presented. Three new species from the Atlantic Forest in Rio de Janeiro state are described, based on both sexes: Arnoliseus cariocasp. nov. from the city of Rio de Janeiro, and Arnoliseus hastatussp. nov. and Arnoliseus falcatussp. nov. from the municipality of Cachoeiras de Macacu. The genus’ genital morphology is discussed in detail and new English terminology for their structures is created. An identification key for all Arnoliseus species is given.


Behaviour ◽  
2001 ◽  
Vol 138 (10) ◽  
pp. 1215-1234 ◽  
Author(s):  
Robert Jackson ◽  
Chris Carter ◽  
Michael Tarsitano

Abstract Portia is a genus of web-invading araneophagic jumping spiders known from earlier studies to derive aggressive-mimicry signals by using a generate-and-test algorithm (trial-and-error tactic). Here P. fimbriata's use of trial-and-error to solve a confinement problem (how to escape from an island surrounded by water) is investigated. Spiders choose between two potential escape tactics (leap or swim), one of which will fail (bring spider no closer to edge of tray) and the other of which will partially succeed (bring spider closer to edge of tray). The particular choice that will partially succeed is unknown to the spider. Using trial-anderror, P.fimbriata solves the confinement problem both when correct choices are rewarded (i.e. when the spider is moved closer to edge of tray) and when incorrect choices are punished (i.e. when the spider gets no closer to edge of tray).


2013 ◽  
Vol 9 ◽  
pp. 26-34
Author(s):  
Maciej Bartos

Decisions made by predators during predatory encounters are often based on multiple factors that may influence the outcome of the encounters. For stalking predators their visibility to the prey and the ability of their prey to escape may be important factors influencing predatory success. Hence they are likely to adapt their predatory behavior when approaching prey on backgrounds with different camouflaging properties, but only if the prey is able to escape. To test whether jumping spiders flexibly adapt their predatory behavior to camouflaging properties of the background and prey type, the behavior of Yllenus arenarius (Araneae, Salticide), a cryptically colored jumping spider hunting leafhoppers (high escape potential) and caterpillars (low escape potential) on two types of background: matching and non-matching for the spiders was analyzed. Background color had a significant effect on the spiders’ jumping distance and their predatory success, but only if the prey had a high escape potential. No differences occurred between backgrounds if the prey could not escape. On camouflaging background the spiders attacked leafhoppers from a shorter distance and had a higher success than on non-camouflaging background.


Zootaxa ◽  
2016 ◽  
Vol 4200 (3) ◽  
pp. 437 ◽  
Author(s):  
WAYNE P. MADDISON

The genus Neon Simon stands alone as a phylogenetically isolated astioid jumping spider, the only member of the Neonini. The new genus Papuaneon is established for the jumping spider Papuaneon tualapa sp. nov. from Papua New Guinea. Resembling a large, hirsute Neon, it is here shown to be the sister group to Neon, based on data from the nuclear 28S and Actin 5C, and the mitochondrial 16SND1 region. Photographs of living specimens are provided. 


2005 ◽  
Vol 61 (4) ◽  
pp. 400-406 ◽  
Author(s):  
Alla Arakcheeva ◽  
Gervais Chapuis ◽  
Vâclav Petricek ◽  
Vladimir Morozov

The incommensurate palmierite-like structure of β-K5Yb(MoO4)4, potassium ytterbium tetramolydate, has been refined in the (3 + 1)-dimensional monoclinic superspace group X2/m(0ρ0)00, with X = [0 0 0 0; ½ ½ 0 0; 0 0 ½ ½; ½ ½ ½ ½] and the unit-cell parameters a = 10.4054 (16), b = 6.1157 (12), c = 19.7751 (18) Å, β = 136.625 (10)°; q = 0.6354 (30)b*. The occupations of the K and Yb atomic positions are described by crenel functions. The structure model reveals a balanced interaction between the atoms of the first and second coordination spheres. It is shown that the third coordination sphere should not be neglected in studies of modulated structures. The ordering of the K and Yb atoms appears to be the driving force for the modulation of all the other atoms.


2015 ◽  
Vol 63 (5) ◽  
pp. 300 ◽  
Author(s):  
Rowan H. McGinley ◽  
Vivian Mendez ◽  
Phillip W. Taylor

The natural history and intraspecific interactions of Servaea incana, a common jumping spider of temperate Australia, are described. S. incana inhabits the trunks of eucalypt trees, where it builds silken retreats and nests under loose bark. Like other jumping spiders, S. incana males use elaborate visual displays (Type I courtship) when they encounter females in the open. Male jumping spiders usually rely on silk-borne vibrations to communicate with females residing within retreats and nests (Type II courtship). S. incana often uses visual displays in this context, because the thin silken walls allow conspecifics to see each other. Adult males that encounter subadult females at retreats sometimes build their own retreat nearby and cohabit until the subadult female moults to maturity, copulating shortly afterwards. Adult females and immature stages of both sexes possess similar display repertoires that contain fewer display elements than the repertoire of males. We found no evidence that visual displays of S. incana contain seismic elements, in contrast to some of its closest relatives. S. incana preys upon a variety of small arthropods and, unusually amongst salticids, ants make up a large portion of the diet. Identified enemies of S. incana include spiders, a pompilid wasp and a mantispid.


1975 ◽  
Vol 66 (2) ◽  
pp. 193-207 ◽  
Author(s):  
R D De Voe

Spectral sensitivities of cells in principal eyes of the jumping spider Phidippus reqius were measured using techniques of intracellular recording. Three types of cells were found. UV cells had peak sensitivities at 370 nm and were over 4 log units less sensitive at wavelengths longer than 460 nm. Green-sensitive cells had spectral sensitivities which were well fit by nomogram curves peaking at 532 nm. UV-green cells had dual peaks of sensitivity at about 370 and 525 nm, but the ratios of UV-to-green sensitivities varied over a 40: 1 range from cell to cell. Moreover, responses of UV-green cells to flashes of UV light were slower than to flashes of green light. Segregation of receptor types into the known layers of receptors in these eyes could not be shown. It is concluded that jumping spiders have the potential for dichromatic color vision.


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