Fiddler crabs use their oversized claws far more as signals than as weapons

Evidence

What he found was they wave them. Up and down, up and down, again and again they raise their claws high and drop them. Dozens of times each minute, thousands of times per hour, hour after hour. When contests get intense, claws clearly function as weapons—dangerously strong claspers capable of inflicting real harm. Yet they also appeared to serve as signals. In fact, for every few minutes of outright fighting, males spent dozens of hours waving. Most of the time, fiddlers were employing their claws as warnings rather than instruments of battle. They were using them for deterrence. — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 366

Categorization

• XREF: Reinforces the run-up thesis that many animal weapons serve deterrence before actual combat—parallels deterrence dynamics in human arms races. — connects to: Fiddler crabs have the largest relative weapons yet rarely fight; Fiddler crabs assess rival claw size and only approach equally-matched opponents. — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 375; Waving a fiddler crab claw incurs measurable energetic costs — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 767 (+1 more)

Related

• Fiddler crabs have the largest relative weapons yet rarely fight (similarity 0.95)
• Fiddler crabs assess rival claw size and only approach equally-matched opponents. (similarity 0.91)
• Weapon size honestly signals fighting ability because growth tracks health and nutrition (similarity 0.87)
• Waving a fiddler crab claw incurs measurable energetic costs (similarity 0.87)
• Costly claw muscle raises male fiddler crab resting metabolism nearly twenty percent (similarity 0.87)
• Waving a fiddler crab claw raises blood lactate measurably. (similarity 0.85)
• Even resting male crabs pay high energy costs for big claw muscles (similarity 0.83)
• Sexual weapons sometimes protect rather than burden their bearers from predators (similarity 0.81)
• Weapons are better signals than body size because they vary from zero to enormous (similarity 0.80)
• Predators evolve counter-tactics that exploit weapon-costly prey (similarity 0.79)
• The same three ingredients trigger weapon evolution across wildly divergent animal clades (similarity 0.79)
• Weapons work primarily as deterrents that prevent fights rather than win them (similarity 0.79)

Broader Connections

• Fiddler crabs assess rival claw size and only approach equally-matched opponents. #corroborates (0.70) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 375
• Waving a fiddler crab claw incurs measurable energetic costs #expands (0.65) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 767
• Weapons are better signals than body size because they vary from zero to enormous #expands (0.60) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 353