Spider Anatomy

This spider was inside our house climbing around on our oven.  It looks a lot like a Long-legged Sac Spider.  According to Field Guide to Insects and Spiders of North America by Arthur V. Evans, these spiders are usually seen in homes where they live inside appliances.  They also bite- and apparently the bite is painful and slow to heal.  Good thing I didn’t know that when I took these pictures!

If you look closely at the spider’s rear, you can see its spinnerets which are the bumps on its abdomen that spider silk comes from.  In fact, if you really look closely, you can see a string of silk coming from one of the spinnerets and leading towards the upper right of the photo.  Spiders have several spinnerets and they usually also spin different types of silk, depending upon what the spiders need it for.

This photo also gives us a good look at the spider’s legs and their segments.  Starting from the dark tip on the leg and working towards the body, the segments are the claw, tarsus, metatarsus, tibia, patella, and femur.  Those names should sound familiar, since we humans have those parts as well (except for the claw of course)!

From this angle we can see the pedipalps which look like short, curled antennae sticking out of the spider’s head.  The pedipalps almost work like extra legs and allow the spider to hold and turn its prey in order to eat it.

  1. Uh,… I love taking shots of spiders, but we have a mutual agreement: They stay outside.
    Living in appliances? Eekkk,…
    Hubby was the first one that told me about biting spiders. Like I really needed that piece of Info :/
    The macro shots are awesome! I do miss the little Critters. Not many of them around here.

  2. Looks like you’ve got a female there, from the narrow palps. There are internet rumors that yellow sac spiders are dangerous, but there is no proof. They can, however, bite, and it has been compared to being stung by a hornet. Ouch!

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