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Tuesday, March 13, 2012


Can you guess whose eyes these are?

Here's another clue: an impressive claw-like pedipalp.

And another (this one gives it away)...

This is the stinger of a California Forest Scorpion (Uroctonus mordax).  The sharp barb is called an aculeus. 

Here's a view from above:

Scorpions are chelicerates, a subphylum of arthropods that includes three classes horseshoe crabs, arachnids (scorpions/spiders/ticks/mites) and sea spiders (more about them in future posts!).

They all have three basic types of appendages: the first pair are called chelicerae small appendages near the mouth that are used for holding and tearing.  The second pair are the pedipalps (greatly enlarged in scorpions).  And then come 4 pairs of walking legs.

If you zoom in to the front of scorpion's carapace, you can see the distinctive chelicerae.  There are two of them, like miniature claws, lined with triangular teeth.  Scorpions lack mandibles, so they tear their food with the chelicerae before ingesting it.

We've encountered these scorpions under logs in the woods (and under doormats and plant pots) in Sebastopol.  They're about 4 cm long.  

I've been trying to find out the derivation of the scientific name.  Mordax apparently means to bite or sting.  Uroctonus has been more challenging to track down.  "Uro" might mean tail, and "ctonus" might mean murderer.  So all together, perhaps this is the Stinger that Murders with its Tail?

I'm not sure exactly why, but Mordax just seems like the perfect name for a scorpion.  It, like all of their anatomy, somehow says, "Beware."  I'm glad I don't live under a log.

1 comment:

Asian Mussel said...

Fitting then that California Moray Eels are named Gymnothorax mordax!