Hydrodynamic constraints on prey-capture performance in forward-striking snakes

Area of Science:

• Zoology
• Biomechanics
• Fluid Dynamics

Background:

• Aquatic snakes (Natrix tessellata) strike prey with open mouths.
• This is thought to be suboptimal due to high drag and prey displacement.
• Observed capture success rates are relatively low (<20%).

Purpose of the Study:

• To investigate the hydrodynamic constraints on prey capture in Natrix tessellata.
• To test the impact of open jaws and bow waves on strike speed and prey interaction.
• To evaluate the potential hydrodynamic advantages of this striking strategy.

Main Methods:

• Utilized laser-scan based computational fluid dynamics (CFD).
• Simulated the fluid dynamics of snake head movement during strikes.
• Analyzed drag forces, prey displacement, and collision dynamics.

Main Results:

• Drag force increases significantly with higher gape angles.
• Strike speed reduction due to drag is less pronounced than expected due to system dynamics.
• Prey displacement was limited (<13% of head length), with frequent forceful collisions.
• Precise aiming is crucial to prevent prey evasion.
• Hydrodynamic advantages were identified for striking at larger prey.

Conclusions:

• The open-jaw strike strategy in Natrix tessellata presents complex hydrodynamic trade-offs.
• While drag is a factor, it may not severely limit strike speed.
• Effective prey capture relies on accurate targeting and may offer advantages for larger prey.
• Further research into snake strike biomechanics and hydrodynamics is warranted.