Supplementary material from: Fiddler crab claws work as a deflection antipredator defence

Fiddler crabs exhibit conspicuous claws used for social signaling, which
may also function as a deflection mechanism by diverting predator attacks
from vital body regions. To test this hypothesis, we used robotic models
replicating the colors and waving display of Gelasimus vomeris, deploying
them in the field to be attacked by Australian brush-turkeys (Alectura
lathami). We analyzed whether attack direction varied with claw
conspicuity. Our results show that models with conspicuous claws attracted
significantly more attacks to the claw, while those with non-conspicuous
claws were primarily attacked on the carapace. This suggests that claw
coloration reduces predation risk by deflecting attacks away from vital
areas. The dataset includes spectral reflectance measurements of models,
3D files for claw replication, and videos documenting both experimental
and natural waving behaviors. This study provides the first evidence of a
claw-deflection strategy in crustaceans.