Wednesday, June 21, 2017

What a Bug!

Reaching for dinner - Click to enlarge  Kate Redmond
Linda Bower sent me a video of a water scorpion, an incredible insect that I hadn't ever heard of.  The scorpion comparison is a stretch with its long front legs lacking claws and rear breathing appendage that neither bends nor stings. There are two genera world wide, Nepinae which are more bug-like and Ranatrinae which look more like a walking stick.

A few facts before you watch the video.  Water scorpions (WS) are Hemiptera or true bugs as they consume their prey as liquids.  They grasp their prey, usually aquatic invertebrates, but occasionally a small fish or tadpole, and stab it with a needle like beak.  It has one channel to inject digestive juice and another to suck out the predigested meal.

Note "jack -knife" front legs to grip prey - Kate Redmond
The cool part of the video is how rapidly it can capture its prey.  While we bipeds are particularly fond of our opposable thumbs as the peak of anatomical evolution, the WS has a primitive but impressive grasp by flexing the last segment of its foreleg like a jackknife.  Now watch the video as it has a Predaceous Diving Beetle larva as an appetizer, then catches a Creeping Water Bug that was dumb enough to land on its back.
 

Now to the interesting tail piece.  Unlike the stinger on its scorpion namesake, this is a harmless breathing device.  They are ambush hunters, hanging upside down on vegetation to grab prey coming by.  To get oxygen they back up to the surface and their snorkle-like tail collects the air supply that they then store between their forewings and the abdomen beneath.  Its respiration is even more complicated as the tail is actually two hair lined filaments that diffuse oxygen into its air bubbles as described in this Northern State University article.


I can imagine a movie like Jaws where scuba divers are pitted against a giant hundred foot water scorpion.  Calling Steven Spielberg!
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* More detail in Brown Water Scorpion by Kate Redmond, aka the Bug Lady who provided these photographs.  She writes a great Bug of the Week blog for the University of Wisconsin, Milwaukee.

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