Death, dying, and spiders

I get a kick out of getting a question from someone, then a little while later seeing something similar or something that relates on one of my newsfeeds.  One of my colleagues asked me a few weeks ago why insects and spiders always die on their back.  I had no idea.  So I did what I always do.  I googled it.

Turns out it has to do with water pressure.  When an insect dies, the pressure of it’s haemolymph (their version of blood) drops and since that is some of what controls their leg muscles, those legs contract in.  That makes them a bit top-heavy, so they wind up on their back.  Go figure!  Smithsonian answers the questions here.  It also has to do with coordination of their nervous system, which obviously doesn’t work when they are dead.  Live Science describes it in more detail.

Then the other day, I see that IFLS has a similar post and this very cool graphic:spider circulation

Go check it out, and share so your friends can learn something new too!

Don’t forget to check out the new Confessions of an Entomologist facebook page too.

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