Propulsion efficiency and imposed flow fields of a copepod jump

Area of Science:

• Fluid dynamics
• Marine biology
• Biophysics

Background:

• Pelagic copepods utilize rapid jumps for essential behaviors like predation and predator evasion.
• These propulsive movements incur significant energetic costs and generate detectable hydrodynamic signals.
• Rheotactic predators can potentially detect copepods through these flow disturbances.

Purpose of the Study:

• To investigate the hydrodynamic consequences and energetic costs of pelagic copepod jumps.
• To analyze the flow fields generated by different types of copepod jumps using computational methods.
• To understand how these flow fields may affect predator-prey interactions.

Main Methods:

• Utilized computational fluid dynamics (CFD) simulations to model copepods as self-propelled bodies.
• Incorporated observed kinematic data of various jump types into the simulations.
• Validated CFD simulations with particle image velocimetry (PIV) data.

Main Results:

• Repositioning jumps create symmetrical vortex rings, potentially offering hydrodynamic camouflage.
• Escape jumps generate a distinct flow trail that may signal the copepod's location to predators.
• High Froude propulsion efficiencies (0.94-0.98) were achieved due to the rapid, impulsive nature of the jumps.

Conclusions:

• Copepod jump kinematics generate distinct hydrodynamic signatures with implications for predator detection.
• Symmetrical flow fields from repositioning jumps may serve as camouflage.
• Asymmetrical flow trails from escape jumps can alert predators, highlighting a trade-off between movement and concealment.