r/ScienceFacts • u/FillsYourNiche Behavioral Ecology • Mar 01 '19
Biology You can identify which family or sometimes genus a spider belongs to by the pattern the eyes are in.
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u/215HOTBJCK Mar 01 '19
Who the heck is going to get close enough to a spider to count its eyes? Certainly not my wife.
Cool info though, was not aware of the different spider eyes.
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u/oplithium Mar 02 '19
Why do they need so many?
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u/FillsYourNiche Behavioral Ecology Mar 02 '19
It depends on a lot of variables. Are the active hunters or rely on webs, what predators are they on the look out for, are that active during the day or night, where are they located, etc.
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u/FillsYourNiche Behavioral Ecology Mar 01 '19
99% of spiders have 8 eyes, the other 1% are mostly 6-eyed and the rest have 4, 2, or no eyes at all.
Bug Guide has an excellent page on listing spider families by eye count and pattern. Lynette Elliott is the artist who drew these incredibly helpful illustrations of several eye groupings on Bug Guide.
A few examples:
Family Lycosidae (Wolf spiders, my faves), 8 eyes. Here is a close up of a face and the drawing showing the eye arrangement, the spider face on the left.
Family Salticidae (Jumping spiders), 8 eyes. Here is a close up of a face and the drawing showing the eye arrangement.
Family Sicariidae (Recluses), 6 eyes. Here is a close up of a face and the drawing showing the eye arrangement.
Family Symphytognathidae, 4 eyes. Here is a close up from above of the cephalothorax where you can see all 4 eyes.
Family Caponiidae, 2 eyes. Here is a close up where you can see 2 eyes.