This all goes back to the idea of cost in an evolutionary sense —when a species develops an ostentatious display like this in order for the males to up their chances of enticing a mate, there should be some trade-off somewhere. Large horns might make it harder for their owners to fly, or it might force them to eat a lot more, or something. But when researchers at the University of Montana set out to discover just how the horns affected rhino beetles' ability to fly, they were shocked to discover that it really didn't. Lead researcher Erin McCullough explained the results to the BBC, with a wonderfully blunt opening description of these beetles:
"Given that males have a giant pitchfork of a horn sticking out of the head, I expected that flying would be cumbersome and awkward. Quantifying flight costs seemed like a good place to start. I was not expecting the horns to have such a small effect on flight. Horns [also] don't appear costly in terms of resource allocation trade-offs, immune costs or survival. So if there are costs associated with carrying and/or producing horns, it definitely isn't obvious what these costs might be."
You can check out the whole article here and their original paper in Proceedings of the Royal Society B: Biological Sciences.
Image by on e³°°° on Flickr.