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Biology

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    $\begingroup$ These images are great nightmare material. $\endgroup$
    – André LFS Bacci
    Commented Apr 18, 2023 at 14:51
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    $\begingroup$ Importantly, cnidarians have more than 2 eyes. Having 2 eyes is more a consequence of bilateral symmetry as all animals with bilateral symmetry have approximately 2 of everything. $\endgroup$
    – Bryan Krause ♦
    Commented Apr 18, 2023 at 15:33
  • $\begingroup$ @BryanKrause very wrong, some of the first bilaterally symmetric animals with eyes have 5 eyes, 3 eyes, or 2 eyes. $\endgroup$
    – John
    Commented Apr 19, 2023 at 0:13
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    $\begingroup$ @BryanKrause Yes, and there many examples of extant bilaterally symmetric animals with > 2 eyes, eg many spiders have 8. Eyes have evolved independently something like 22 times, so there is vast variety that eludes simple generalizations. $\endgroup$
    – Michael MacAskill
    Commented Apr 19, 2023 at 0:34
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    $\begingroup$ great, now I want a 100 trilobyte drive... $\endgroup$
    – Michael
    Commented Apr 20, 2023 at 2:16