You may never have met up with one in real-life, but most likely have seen an image, model, or nature show depicting a rhinoceros beetle. Growing up to 6 inches, they are among some of the largest and impressive beetles on Earth. The male rhinoceros beetles exhibit sizable horns on the head and thorax. These horns are a variety of shapes and sizes. Although they look daunting, members of this group of beetle are harmless to humans due to their inability to bite or sting. The male beetles use their horns to fight other males over female beetles. Each member of this beetle group has a different method of battling their opponents.
Scientists at the University of Missoula had a theory that the shape of the beetle's horns was adapted to their specific fighting style. They believed that the shape of the horns would put them at a disadvantage if they fought with any other method. To test this hypothesis they built biomechanical models of the horns of 3 different species of rhinoceros beetles. The models were tested by submitting them to 3 different types of force: pressure from above and the side and twisting. Sure enough, they found that each type of horns showed the least amount of stress when it experienced a similar force to that of which the actual beetle experiences. The method the beetle used to fight was the method best suited to the shape of the horn. The researchers found that the key to these advantages in battle did not have to do with how large or ornamental the horns were. They concluded it was the shape of the cross section of the horns. After Micro-CT scans the scientists found that fairly small differences in the shape of this part of the horn could make a big difference in how the beetles fight.
We see time and time again how adaptations in plants and animals such as the horns on beetles, the beak shape of birds, or the chemicals a plant produces, make a huge difference in the success of these organisms. The adaptation of form to function and the diversity of life on this planet continues to be logical, smart and awe-inspiring all at the same time.
Plant and Animal Adaptation Activities and Resources:
Scholastic's StudyJams (interactive) on Animal Adaptations
"Our Wild Neighbors" (interactive website) from the National Park Service
Animal Adaptations Educational Interactive Websites
NHPTV's "Natureworks" streaming episode: Adaptation
Science Fair Project: Plant Neighbors: Friends or Foes? Plant Adaptations- Written and Developed by me!