DOI: 10.5061/dryad.xsj3tx9s8
title: Supplementary material from: Fiddler crab claws work as a deflection antipredator defence

description: 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.
description: # Supplementary material from: Fiddler crab claws work as a deflection
 antipredator defence *Diogo J. A. Silva, Samuel B. Powell, Marilia F.
 Erickson, Fabio Cortesi, Daniel M. A. Pessoa, Karen L. Cheney* --- ##
 Repository Content ### Description: This package contains all the 3D
 materials necessary for printing the physical parts of the robotic crab,
 along with videos demonstrating its functionality. ### Files: #### Robotic
 Crab Schematic: * *assembly_Drawing_v3.pdf* – Robotic crab schematic ####
 Individual Components of the Robotic Crab in .stl Format: These files
 contain all the separate parts that form the robotic crab. They are
 provided in `.stl` format and can be opened with open-source software
 (e.g., FreeCAD). * *frame_v25.stl* – Support structure of the robotic crab
 * *gear-20x0.75_v26.stl* – Robotic crab gear *
 *gelasimus_vomeris_natural_claw.stl* – Original scanned claw of the
 fiddler crab *Gelasimus vomeris* *
 *gelasimus_vomeris_natural_claw_modified.stl* – Scanned claw modified for
 attachment to the robotic crab * *post_v13.stl* – Component of the robotic
 crab * *rack_v22.stl* – Component of the robotic crab #### 3D Model with
 All Parts Assembled: This file contains the complete assembled model of
 the robotic crab. It requires Fusion 360, a proprietary software that can
 be downloaded for free. If you prefer to use only open-source software,
 please use the `.stl` files with separate parts. * *assembly_v15.f3z* ####
 Pololu Micro Maestro code used to control claw movement *
 *code_robocrab_motor_control_setting.txt* #### Videos of the Robotic Crab:
 * *Supplementary_video_1.mp4* – Video of the robotic crab *
 *Supplementary_video_2.mp4* – Example of a Brush-turkey attacking the
 robotic crab * *Supplementary_video_3.mp4* – Video of a *Gelasimus
 vomeris* fiddler crab waving #### Supplementary Tables: *
 *Supplementary_table_1.csv* – List of experiment locations *
 *Supplementary_table_2.csv* – Binomial regression output #### Variables of
 the Supplementary table 2: * *treatmentB* – Paint treatment applied to the
 robotic crab in the experiments, where both the claw and carapace were
 painted black. * *treatmentC* – Paint treatment applied to the robotic
 crab in the experiments, where the claw was painted orange and the
 carapace was painted blue. * *attack_positionfront* – Position relative to
 the robotic crab where the Brush-turkey attacked, i.e., it attacked the
 model from the front. * *attack_positionlateral* – Position relative to
 the robotic crab where the Brush-turkey attacked, i.e., it attacked the
 model from the side. * *illuminantshade* – Represents the shaded ambient
 light conditions at the location where the robotic crab was placed. ---
 When using the data available in this repository, please cite the original
 publication and dataset. For further information, contact
 [diogojackson@hotmail.com](mailto:diogojackson@hotmail.com). ---