So, you’re ready for the next step in facing your fears. Your curiosity has proven that deep down, you’re not completely terrified of said creature that use to make you fall into a fetal position until you decided to burn the entire house down just to be sure everything was right in the your world.  I am very excited for you, because once upon a time, I was that same person. I, too, jumped into the arms of others if an eight-legged foe came crawling on by. I’m not even sure why I was so afraid, I just knew the crippling fear was so real.

It actually wasn’t until a couple years ago I overcame my fears of spiders. It was through a newfound love of photography that erupted something inside of me to look at spiders in an artistic way, and not in a “KILL IT” way.  Through photography, I was able to capture an entirely different world than the one I was apart of. Being the nerd that I am, I wanted to know about my subjects, thus creating an instant arachnid lover.

So, moving on to the anatomy… There are two basic segments of a spider; the cephalothorax (or prosoma) and the abdomen (or ophisthosoma). Where insects have three body parts- head, thorax and abdomen, arachnids have just two. The first segment, being the cephalothorax, houses all appendages and the upper side (dorsal side) is covered with a tough outer carapace. The cephalothorax also contains the eyes, mouth fangs (chelicerae), pedipalps, brain, stomach and the gland that makes venom.

The abdomen is composed of thin skin, as opposed to the hard cephalothorax carapace. The abdomen contains many of the important internal organs, such as; intestines, heart, lungs, digestive gland, etc… Finishing off with the two external signature spinnerets.

Arachnids are just like any other arthropod, as they wear their skeleton on the outside.  This is called the “exoskeleton” and all spiders shed (or molt) this while growing. A spiders exoskeleton is made up of several cuticle layers of protein and chitin– it’s kind of similar to wood particle board. This provides a nice, protective shell that has one draw back, it can’t grow. Once a spider becomes “too big for its britches” it has to stretch its legs into something a little more comfortable- a new body! Some spiders molt several times in their lifetime, and others will only molt a few times. Regardless, it’s a necessary natural event that happens in every spiders life.

We’re told as children that all spiders have eight eyes. It’s kind of easy to remember, eight legs, eight eyes. But, did you know there are spiders that have no eyes? There are about 40,000 known species of spiders in the world and 99% of them have eight (simple) eyes. The leftover 1% is made up of mostly (still simple) six-eyed spiders with the exception of a few that actually have no eyes (Such as this really cool huntsman spider). A good clue to typing a spider is to look at their eye arrangement. We know that long-jawed orb weavers (family Tetragnathidae) have eye arrangements that are in rows of two, resembling something like this ( :::: ). We also know that jumping spiders (family Salticidae) have eyes that are grouped in fours; four anterior (front) eyes and four posterior (back) eyes ( .. …. .. ).  You would think with all these eyes spiders would have GREAT vision, but that’s quite the contrary. Most spiders have horrible vision, excluding families like the jumping spider which actually have great vision (more on that another time).

Think you know a good portion of your spider anatomy now? Think again! In my next article, we’re going to dig even DEEPER to see just how these guys really work. From breathing to how much silk they can produce, we’re going to cover it all!