Morphology, performance and fluid dynamics of the crayfish escape response
Jocelyn Hunyadi1, Todd Currier2, Yahya Modarres-Sadeghi2
1Department of Biology, Amherst College, Amherst, MA 01002, USA.
The Journal of Experimental Biology
|June 21, 2020
Summary
Sexual selection impacts crayfish escape performance. Males with larger claws (chelae) were slower, while females with wider abdomens and longer uropods (tail appendages) were faster.
Area of Science:
- Animal behavior
- Crustacean biology
- Evolutionary morphology
Background:
- Sexual selection can lead to exaggerated traits that may hinder physical abilities.
- Crayfish morphology, particularly male enlarged claws (chelae), may affect their escape responses.
Purpose of the Study:
- To investigate the relationship between sexual dimorphism in morphology and the tail-flip escape response in rusty crayfish (Faxonius rusticus).
- To understand how specific body parts contribute to escape velocity and force.
Main Methods:
- Comparative morphological measurements between male and female rusty crayfish.
- Analysis of tail-flip escape velocity and force.
- Particle image velocimetry (PIV) to visualize fluid dynamics during escape.
Main Results:
- Males had larger chelae and deeper abdomens; females had wider abdomens and longer uropods.
- Larger chelae correlated with lower escape velocity; longer abdomens and uropods correlated with higher escape velocity.
- No sex differences in maximum tail-flip force, but uropod length positively correlated with force in males. PIV confirmed vortex formation for propulsion.
Conclusions:
- Exaggerated male morphology (chelae) can negatively impact escape performance.
- Female morphology is better adapted for faster escape responses.
- This study provides the first evidence of vortex formation contributing to propulsion in decapod crustaceans.
