Longer development provides first-feeding fish time to escape hydrodynamic constraints

Area of Science:

• Ichthyology
• Developmental Biology
• Fluid Dynamics

Background:

• Fish larvae face significant hydrodynamic constraints when feeding due to their small size.
• Ontogenetic state and developmental timing vary considerably among fish species, impacting early life stages.

Purpose of the Study:

• To investigate the functional effects of prolonged development on first-feeding performance and hydrodynamics in fish.
• To differentiate the roles of hydrodynamics versus developmental state in prey capture success.

Main Methods:

• Compared first-feeding performance and hydrodynamics of zebrafish and guppy offspring of similar size but differing developmental times.
• Manipulated water viscosity to control the hydrodynamic regime (Reynolds number).
• Utilized flow visualization to analyze suction fields and bow wave dynamics.

Main Results:

• Guppy offspring captured prey from significantly greater distances (1.0 mm vs. 0.2 mm) with higher success rates (90% vs. 20%) than zebrafish larvae.
• Feeding performance did not solely scale with Reynolds number, indicating developmental factors are crucial.
• Zebrafish larvae generated a limited suction field within their bow wave, while guppies extended theirs beyond it due to advanced oral jaw protrusion.

Conclusions:

• Prolonged development and advanced ontogenetic state enable fish to overcome hydrodynamic limitations associated with small size.
• Developmental plasticity in feeding apparatus, like jaw protrusion, is key for successful prey capture in challenging hydrodynamic environments.
• The study highlights how extended development provides a critical window for fish to adapt and thrive in early feeding stages.