Friday, May 8, 2015

Aren't Bombardier Beetles Cool?!

This week we welcomed an expert on bombardier beetles to the classroom.

Eric Arndt, a MIT researcher, brought his work with him - giving each 2nd, 3rd, & 4th grader their own long-preserved beetle!

Eric explained to us that most species of beetles fall prey to birds, mammals, reptiles, and amphibians. And that even other invertebrates: spiders, ants, praying mantis, and larger beetles will prey on beetles. But the bombardier beetle, that Eric has studied, manages to avert hungry mouths by using chemicals for defense.

Many arthropods produce toxic bad-tasting chemicals to make themselves less desirable as food but the bombardier is unique. It sprays a hot (as hot as boiling water!) irritating mixture of chemicals. Eric's research has found that the bombardier is able to produce this explosion by combining two chemicals but that the beetle will keep these two chemicals separate until the last moment; just before it is needed.

By producing a noxious spray - a series of short jet bursts - there are very few predators who would care to eat the bombardier.

Eric described how he and his collaborators were able to use specialized x-ray imaging to see inside living beetles! We saw a video that Eric made, showing the internal structures of the beetles abdomen magnified under a powerful microscope.  His work allows us to see, for the first time, inside a live beetle while it sprays its super-hot defense.

Then Eric took us on a beetle hunt outdoors.

We learned that these nocturnal animals can be found under rocks and logs, beside streams during the day. Later in the day, we used guides to help us to identify the arthropods we found.

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