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    Is it an ant? Is it a plant? No, it's a spider!    
      
     Date:   
         May 17, 2023   
     Source:   
         Cell Press   
     Summary:   
         A species of tiny, colorful jumping spider employs two lines of   
         defense to avoid being eaten: camouflaging with plants and walking   
         like an ant.   
      
         Researchers report that this combination of camouflage and movement   
         mimicry helps the spiders evade spider-eating spiders but does   
         not deter hungry praying mantises.   
      
      
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   FULL STORY   
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   A species of tiny, colorful jumping spider employs two lines of defense   
   to avoid being eaten: camouflaging with plants and walking like an ant.   
      
   Researchers report May 17th in the journal iScience that this combination   
   of camouflage and movement mimicry helps the spiders evade spider-eating   
   spiders but does not deter hungry praying mantises.   
      
   Mimicking ants is a good defense option because they do not make for good   
   eating; ants often have spiny defenses and biting mandibles (and they're   
   not afraid to fight back), and many also carry chemical repellants or   
   venom. Though the focal spider of this study -- Siler collingwoodi --was   
   already known to move in an ant-like fashion, the researchers wanted to   
   know how accurate its mimicry is, whether it mimics more than one ant   
   species, and how effective this mimicry is at discouraging predators.   
      
   The research team also explored the role of the spider's brilliant   
   coloration.   
      
   "Unlike typical ant-mimicking spiders that mimic the brown or black   
   body color of ants, S. collingwoodihas brilliant body coloration,"   
   says first author Hua Zeng, an ecologist at Peking University. "From a   
   human'sperspective, it seems to blend well with plants in its environment,   
   but we wanted to test whether their body coloration served as camouflage   
   to protect against predators."  To understand how ant-mimicry helps these   
   spiders avoid being eaten, the researchers collected wild ant-mimicking   
   spiders from four geographic locations in southern Hainan, China,   
   and brought them back to the lab. For comparison, they also collected   
   another type of jumping spider that doesn't mimic ants, as well as five   
   co-occurring ant species that they thought might serve as models.   
      
   Back in the lab, the researchers characterized and compared how the ants   
   and spiders moved in terms of how they used individual limbs, as well   
   as their speed, acceleration, and whether they followed a straight path   
   or took a more tortuous trajectory.   
      
   They found that, rather than jumping like most jumping spiders,   
   S. collingwoodi move like ants: by raising their front legs to mimic   
   an ant's antennae, bobbing their abdomens, and lifting their legs   
   to walk in an ant-like manner. Of the five ant species, the spiders'   
   walking style most closely resembled the three smaller ant species,   
   who are also closer to it in size.   
      
   "S. collingwoodiis not necessarily a perfect mimic, because its gait   
   and trajectory showed high similarity with multiple ant species," says   
   Zeng. "Being a general mimic rather than perfectly mimicking one ant   
   species could benefit the spiders by allowing them to expand their range   
   if the ant models occupy different habitats."  Next, the researchers   
   tested the spider's defenses against two likely predators: a similarly   
   sized jumping spider with color vision that specializes in preying upon   
   other spiders (Portia labiata) and a praying mantis (Gonypeta brunneri)   
   that is a generalist predator with a monochromatic visual system.   
      
   To explore the role of color camouflage, the researchers modeled how the   
   two predators would perceive S. collingwoodirelative to the other prey   
   species against the background of two plants that the spiders live on --   
   the red- flowering West Indian jasmine (Ixora chinensis) and the Fukien   
   tea tree (Carmona microphylla). They found that the ant-mimicking spiders   
   were better camouflaged from both spider and praying mantis predators   
   on the jasmine plant than the tea tree plant.   
      
   When the predators were given the choice of the ant-mimicking spider   
   and the other jumping spider, the predatory spider was more likely to   
   attack the non- mimic; out of 17 trials, the spider launched 5 attacks,   
   all of which were towards the non-mimic. Praying mantises, however,   
   attacked both prey species with equal alacrity.   
      
   "We initially thought that both predators would behave similarly in the   
   antipredation experiments, but in fact the simulated ant locomotion   
   of Siler collingwoodi only worked for the jumping spider predator,   
   while the praying mantis showed indiscriminate attacks on both ants   
   and mimics," says senior author Wei Zhang, an evolutionary ecologist at   
   Peking University.   
      
   This difference might be driven by each predator's likelihood of being   
   injured from eating an ant. The praying mantises are much larger than   
   their prey, so they can get away with eating spiny ants without risking   
   grave injury, but this is not the case for the predatory spiders.   
      
   "For the spider predator, a random attack on an ant could result in   
   injury, so they are very careful predators and will only attack if they   
   can distinguish S.   
      
   collingwoodifrom ants with a high degree of certainty," says Zhang.   
      
   However, losing a limb compromised the ant-mimicking spiders' ability   
   to avoid the predatory spider's attention, probably by preventing them   
   from accurately mimicking ants.   
      
       * RELATED_TOPICS   
             o Plants_&_Animals   
                   # Spiders_and_Ticks # Animals #   
                   Insects_(including_Butterflies) # Invasive_Species   
             o Earth_&_Climate   
                   # Exotic_Species # Ecology # Environmental_Policy #   
                   Weather   
       * RELATED_TERMS   
             o Hobo_spider o Widow_spider o Spider_silk o Black_widow_spider   
             o Yellow_sac_spider o Spider o Brown_recluse_spider o Tarantula   
      
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   Story Source: Materials provided by Cell_Press. Note: Content may be   
   edited for style and length.   
      
      
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   Journal Reference:   
      1. Hua Zeng, Dong Zhao, Zixuan Zhang, Huize Gao, Wei Zhang. Imperfect   
      ant   
         mimicry contributes to local adaptation in a jumping   
         spider. iScience, 2023; 106747 DOI: 10.1016/j.isci.2023.106747   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/05/230517122115.htm   
      
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