Thursday, April 03, 2008

Here Come The Rhinoceros
and The Bombardier!

The order Coleoptera is the largest insect order with its many varieties of amazing beetles. When teaching entomology, our students would collect many varieties of beetles including the Rhinoceros Beetle, one of our largest beetles. They were always amazed with its size.

Rhinoceros beetles are also the strongest animals on the planet, proportionally. They can lift up to 850 times their own weight. To put this into perspective, if a human of average height and weight had the strength of the rhinoceros beetle, it would be able to lift a 65 ton object, for example, an Abrams Tank. Females resemble monstrous spotted June beetles while the males look much more exotic and possess a horn on both the pronotum and head. The horns of the male are used in fighting over females and food. Note the collection of males below.

I remember one day we were collecting on the banks of Cedar Creek when one of the class yelled something about puffs of smoke. Yes, she had discovered the wonders of another beetle, the bombardier beetle.

There on the waters edge were bombardier beetles and they were spitting out their dangerous jet of venom to ward off predators. (Probably they were reacting to her probing collecting technique.)

The beetle's abdomen essentially harbors a small chemical lab and combustion chamber. The gases react inside the confined chamber, eventually cranking up the heat and pressure to a point at which a valve is forced upon, and the toxic jet spurts out. From twin ‘exhaust tubes’ at his tail, this beetle fires into the face of his enemies boiling-hot noxious gases with a loud pop.

The defensive spray of the bombardier beetle Stenaptinus insignis is ejected in quick pulses (at about 500 pulses per second) rather than as a continuous stream. The pulsation may be a consequence of intermittency in the explosive chemical process that generates the spray. The ejection system of the beetle shows basic similarity to the pulse jet propulsion mechanism of the German V-1 "buzz" bomb of World War II.

Researchers from Leeds University have replicated the process in the lab, and a company called Biomimetics 3000 plans to explore the possibility of applying the findings to medical technology, plus inhalers, fire extinguishers and even car fuel-injection systems. Oh, the wonders of entomology!


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