Waving a fiddler crab claw raises blood lactate measurably.

Evidence

13. Masatoshi Matsumasa and Minoru Murai were able to measure the energetic costs of fiddler crab claws in action by tracking changes in blood glucose (a sugar used to power activity) and blood lactate (a chemical by-product of metabolism and an indication of energy burned) as animals performed various behaviors. By measuring baseline lactate levels in resting animals, and comparing this to the elevated levels they detected during fights, Matsumasa and Murai showed that the energetic cost of waving a claw was substantial. — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 767 (#corroborates, via linked claim)

Resting metabolic rates of males with big claws are almost 20 percent higher than those of females (who lack enlarged claws) simply because of the costly muscles inside the claw. Waving the claw around or using it to fight is even more expensive, and the bigger the claw, the steeper the energetic costs. — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 303 (#expands, via linked claim)

Categorization

• XREF: connects to: Waving a fiddler crab claw incurs measurable energetic costs — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 767; Costly claw muscle raises male fiddler crab resting metabolism nearly twenty percent — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 303

Related

• Costly claw muscle raises male fiddler crab resting metabolism nearly twenty percent (similarity 0.95)
• Waving a fiddler crab claw incurs measurable energetic costs (similarity 0.93)
• Even resting male crabs pay high energy costs for big claw muscles (similarity 0.91)
• Fiddler crabs have the largest relative weapons yet rarely fight (similarity 0.89)
• Fiddler crabs use their oversized claws far more as signals than as weapons (similarity 0.85)
• Fiddler crabs assess rival claw size and only approach equally-matched opponents. (similarity 0.79)
• Weapon size honestly signals fighting ability because growth tracks health and nutrition (similarity 0.79)

Broader Connections

• Waving a fiddler crab claw incurs measurable energetic costs #corroborates (0.85) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 767
• Costly claw muscle raises male fiddler crab resting metabolism nearly twenty percent #expands (0.70) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 303