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So, look who I found floating in the cats' water bowl this morning.

How did it get there? The first guess is that it climbed in looking for water. Given that water bowl is glass and scorpions can't climb glass, it doesn't seem likely.

Guess two is the cat who likes to dip his "toys" in his water bowl caught the scorpion and decided to "wash" it. In any case, apparently scorpions aren't good swimmers.

I recently saw a photograph of a grasshopper fluorescing under UV light. The photographer said he used a regular camera to capture the image. Ever since, I've been eager to give it a try. Because even drowned scorpions are known to fluoresce,  here was my chance.

I took the bowl with the scorpion into a windowless room and turned off the light. Then I turned on a UV light (blacklight). The scorpion glowed a greenish color. I used the "night mode" setting on my camera to capture the above photograph (I think I need to work on my method.)

Why do scorpions fluoresce when exposed to ultraviolet light? The current theory is that it is part of a chemical process in the scorpion's "skin" that allows it to detect and avoid ultraviolet light. This makes sense because scorpions are active at night and hide under things away from the sun during the day.

Now if they could only avoid water...

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We've never discussed arachnids in detail here at Bug of the Week. Let's find out what we've been missing.

Spiders and their relatives belong to the class Arachnida. How can you tell whether a creature belongs to this group? Arachnids have two body regions called the prosoma (part with eyes and legs) and opisthosoma (rear section). Arachnids have eight legs and they do not have antennae, although they do have two short appendages in front called pedipalps that sometimes may be mistaken for antennae.

wolf-spider-1

Although almost anyone can recognize a spider, there are a number of related arachnids that are less well known.

Scorpions (Order Scorpiones)

scorpion-anatomy

Scorpions have are pincer-like pedipalps  and their opisthosoma is elongated into a relatively thick tail with a stinger on the end.

Like most other arachnids, scorpions are nocturnal. They come out at night to catch insects and other arthropods.

Related posts:

Psuedoscorpions

(Public domain photograph by Alex Wild)

These tiny creatures have pinchers like scorpions (red in this photograph), but have no tail and no stinger. They are often found in compost heaps where they feed on even smaller insects and mites.

Wind Scorpions or Sunspiders

sunspider1These desert arachnids have large chelicerae or jaws that they use for catching insects. They can also use their jaws to stridulate, or make a noise. They don't have a tail.

Related post:  Sunspiders

Whip Scorpion or Vinegaroon

giant-vinegaroon

Unlike all other arachnids, the whip scorpions have a thin tail at the end of the opisthosoma. The pedipalps are robust. In contrast the first pair of legs are thin and have a sensory function similar to antennae.

Vinegaroons have vinegar in their names because they can spray high concentrations of acetic acid if threatened.

Never seen one before? BBC Earth Unplugged has a video of one spraying.

 

Mites and Ticks (Order Acarina)

mite-red-closeThe two body regions are difficult to see in mites and ticks. Their bodies are unsegmented, like small blobs. Also, their legs tend to be quite short relative to their body size.

Certain kinds of mites are among the few arachnids that feed on plants. The red mite in the photograph is an insect predator.

Daddy Long-legs or Harvestman (Order Opiliones)

daddy-long-legLike the mites, the harvestman have what looks like a single oval body region. Unlike the mites, they have long thread-like legs.

Harvestmen differ from spiders by possessing fewer eyes, having only two rather than six or eight. They also lack both venom and silk glands.

Some species of harvestmen are omnivores or scavengers rather than true predators.

Want to learn more?

A few spider identification basics

Check out our growing list of children's books about spiders

spider-books-for-kids

What would you like to know about arachnids?

A few days ago I needed a glass vase for a project. When I pulled it down from the shelf, look who I found inside:

scorpion-clear-stingerFortunately scorpions can't climb glass, so it was definitely trapped in there.

scorpion-close-upAlthough the lighting was less than ideal, it was a good opportunity to see the scorpion parts close up.

scorpion-anatomyIf you are interested in learning more about scorpion anatomy, try our previous post about scorpions.

Scorpions are most active during the summer in Arizona. They hunt for insects at night and hide during the day. People usually don't like them very much because they can deliver a painful - and potentially health-threatening if it is a bark scorpion - dose of venom when they sting.

Scorpions have an intriguing side, however. One really cool thing about scorpions is that they have a natural fluorescence. They glow at night under ultraviolet lights. See, for example, in this video:

Still not convinced scorpions can be interesting? Wired Magazine recently had an article about a doctor who is researching the use of a component of scorpion venom to mark brain tumors. Fascinating!