Sunday Sketch: Horny Beetles

The horn of the giant rhinoceros beetle (Trypoxylus dichotomus) is a classic example of an elaborate trait that arises due to sexual selection. These beetles use their horns to fight over females and these fights get intense. So intense that males are able to break their horns off during vigorous fights with other males. Surprisingly, it is the larger horned males that are more likely to break their horn, indicating that mechanical limitations and tradeoffs select for horns that aren’t too big. Still, these horns are by no means totally fragile; certain species of rhinoceros beetles can lift 850 times their weight. This is the equivalent of a human lifting nine elephants!

Sketch contributed by Maggie Creamer

Fact contributed by Adrian Perez

Sources:

https://www.nwf.org/Educational-Resources/Wildlife-Guide/Invertebrates/Rhinoceros-Beetles

McCullough, E.L., 2014. Mechanical limits to maximum weapon size in a giant rhinoceros beetle. Proceedings of the Royal Society B: Biological Sciences281(1786), p.20140696.

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