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Cake day: 2024年9月3日

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  • Don’t let the sailors tell you you have to cross oceans to circumnavigate the globe! Just walking around the headwaters of the Pregolya River is equivalent.

    While this would have worked in Euler’s time, the puzzle in fact became unsolvable around 1873 when canals were built in the Masurian lakes effectively connecting a tributary of the Pregolya with a tributary of the Vistula to the south and cutting of this route. I assume the canals were constructed by mathematicians trying to close this loophole. Maybe hopping across lock gates when they’re closed doesn’t count as a bridge tho?


  • seaplant@slrpnk.nettoScience Memes@mander.xyzSpidey Senses
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    7 个月前

    The Wikipedia page on ant mimicry is full of fun facts, but the relevant bits:

    Jumping spiders in the genus Myrmarachne are Batesian mimics

    Batesian mimics lack strong defences of their own, and make use of their resemblance to a well-defended model, in this case ants, to avoid being attacked by their predators.

    Studies on this genus have revealed that the major selection force is the avoidance of ants by predators such as spider wasps and other larger jumping spiders.

    But also (not specific to Myrmarachne):

    Ant mimics can be myrmecophilous, with the mimics and their ant models living commensally together. In the case of ants, the mimic is an inquiline in the ants’ nest. Such mimics may in addition be Batesian or aggressive (predator) mimics. To overcome ants’ powerful defences, mimics may imitate ants chemically with ant-like pheromones, visually, or by imitating an ant’s surface microstructure to defeat the ants’ tactile inspections.