Beetle horns can reach 30 percent of male body weight

Evidence

Beetle horns are impressive things. They form during metamorphosis when parts of the body wall grow into rigid protrusions that stick out from the body proper. Horns can be curved, straight, broad, or branched, depending on the species. In many ways they resemble the antlers of moose or elk. Like antlers, beetle horns are typically a male trait. And, like antlers, horns in the largest males can reach enormous proportions. Sometimes a horn will comprise as much as 30 percent of the body weight of a male. If you were to scale these animals up to human dimensions, this would be the equivalent of producing a pair of arms or another leg and wearing it on your head. — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 192

Categorization

• XREF: The 30-percent weight figure invites comparison with earlier chapters’ extremes in antlers and other animal weapons. — connects to: Beetle horns can be impressively large yet nearly cost-free to produce and use — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 810

Related

• Beetle horns can be impressively large yet nearly cost-free to produce and use (similarity 0.90)
• Horn growth is nine times more nutrition-sensitive than genitalia in beetles (similarity 0.85)
• Weapon growth is far more resource-sensitive than other body parts (similarity 0.82)
• Extreme weapons across many insect species stunt eyes, wings, antennae, and testes (similarity 0.79)
• Closely related beetle species can differ sharply in horn possession (similarity 0.79)
• Tunneling behavior predicts horn evolution in dung beetles (similarity 0.79)
• Tunneling dung beetles guard burrow entrances and evolve horns; rollers do not (similarity 0.78)
• Smaller-horned males usually lose escalated dung beetle fights (similarity 0.78)