Thursday, January 17, 2013

Living Fossil: It Stings, Pinches and Glows!

Since one of my other living fossil posts was so popular I have decided to do quite a few more for you.  The first one for the new year is an animal that is almost as old as its relative the horseshoe crab, the scorpion!

Scorpions are considered arachnids which means they have eight jointed legs.  They also breathe with organs called book lungs which are believed to have evolved from gills (more on that in a bit).  Examples of other arachnids are spiders, ticks, mites, harvestmen (commonly misidentified as "daddy long legs") and solifugae (Also referred to as camel spiders.  Look it up on youtube if you dare!) .    Two of the pieces of a scorpion's mouth have been modified by evolution to be weapons in the form of pincers similar to those on a crab.  At the end of the abdomen, there is a long tail that ends in a stinger.  All scorpions possess venom in this stinger.  Few species possess venom dangerous enough to really harm a person, however.

A reference to further learn your scorpion parts.

So what makes scorpions living fossils?  Well the oldest scorpion on the fossil record comes from the Silurian period 430 million years ago!  That's not quite as old as the oldest horseshoe crab (450 million years) but still very very old regardless, much older than the first dinosaurs at least.  Whats interesting is that the animals that these fossils belonged to and many others from around that time period actually lived under the ocean and would have breathed with gills much like those on modern horseshoe crabs most likely.  These ancient marine scorpions could get big too.  Real big.  One species named Brontoscorpio or "Thunder scorpion"  (Good name for a metal band anyone?) grew to be over three feet in length.

Prehistoric scorpion fossil. 

As you can see from the photo above.  Scorpions have changed very little of their anatomy over the past few hundred million years.  Much like the crocodilians, they go by the "if it ain't broke don't fix it" evolutionary strategy.  Who's to argue?  They have dangerous pincers in the front, venomous stinger in the back and a tough outer shell.  What else do they need?

Oh, memebase, they aren't really nightmares!  You just need to get to know them a bit more.  For instance did you know that scorpions are actually caring mothers?  Most species of scorpion mothers will have around ten babies at a time (although some can have up to one hundred!) which are born alive unlike many other invertebrates which hatch from eggs.  The babies then all climb onto their mother's back where she can protect them from predators, make sure they don't dry out and feed them by mushing up prey items with her pincers until the food is soft enough for them to eat.  Cute, right?

Emperor Scorpion (Pendinus emperator) with young.  Photo taken by me several years ago at my job.

Oh yeah one more thing I should mention.  Scorpions glow under black light.  They can do this thanks to fluorescent properties in their exoskeletons.  Scientists are still unsure as to the exact evolutionary reasons for this though.  People who hike or camp in areas where scorpions live carry black lights to check their sleeping bags at night to make sure they don't share close quarters with one of these venomous arachnids. 

WHO WANTS TO RAVE? *cue techno music*

Like I stated under that one photograph, I do work with scorpions at my job.  Here is a quick little video I filmed for you all with a little more information and also so you can see one of these fascinating animals in action.

Hope you liked learning about scorpions!  I have several more living fossils to post about in the future and lots more videos too!  As always if you have any questions you are more than welcome to message me on our facebook page

Works Cited

Andrew Jeram (June 16, 1990). "When scorpions ruled the world". New Scientist.

 Lourenco, W. R. (2000). "Reproduction in scorpions, with special reference to parthenogenesis". European Arachnology: 71–85.

Stachel, Shawn J; Scott A Stockwell and David L Van Vranken (August 1999). "The fluorescence of scorpions and cataractogenesis". Chemistry & Biology (Cell Press) 6 (8): 531–539. doi:10.1016/S1074-5521(99)80085-4. PMID 10421760

No comments:

Post a Comment