I have once made an observation that a spider apparently resided on a wall that had almost the same colour as the spider him-/herself. I lived at this location for several months and could see the spider almost daily.
I am certainly not an expert on spiders, nor am I an expert on animal cognition. I tried to question why the spider apparently chose this location. Since houses are painted repeatedly, evolution seemed an impossible explanation (this would imply survival of the fittest, because the spider was best adapted to the environment, where several generations of the spider subsequently resided there). This house was the only house in this area that was painted in this colour.
Rather, it seemed that the spider deliberately chose this location, because the spider recognized his/her own look and therefore knew that he/she is least likely spotted on this wall, which gave him/her an advantage to catch prey and to remain unseen by predators. This, however, would require remarkable cognitive abilities. I would be grateful for an opinion of an expert or for stimulating discussion among lay people like myself. See below for a picture of the spider.
Many thanks and best wishes,
Rainer
I work on (teleost) fish and am not a spider expert. There are spiders that can change colour and choose backround see e.g. https://www.researchgate.net/publication/279567360_Camouflage_of_predatory_crab_spiders_on_flowers_and_the_colour_perception_of_bees_Aranida_ThomisidaeHymenoptera_Apida
https://www.researchgate.net/publication/255684184_Substrate_preference_in_a_colonial_spider_Is_substrate_choice_affected_by_color_morph
However, I also want to point out that selection per se may remove those spiders that do not blend into the background. Only those that are camouflaged will be left. This will act in the present generation. In the speciation litterature selection against immigrants is termed "immigrant inviability".
Best regards,
Ola
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Dear Ola,
thank you so much for your great reply and for the links to the manuscripts. I think your explanation about selection is an excellent one. I cannot guarantee that it worked here, because spiders in this area did not seem to have a lot of predators, but as a lay person I am certainly no expert on this. In Addition, a small number of predators might be enough to have caused this effect. Therefore you might be very well right. Thanks again.
Yours sincerely,
Rainer
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