Unifying fluidic excretion across life from cicadas to elephants

Area of Science:

• Biofluid dynamics
• Zoology
• Fluid mechanics

Background:

• Current fluid urination models are primarily based on mammals and suggest jetting is limited to animals over 3 kg.
• Viscous and surface tension forces are thought to constrain fluid jetting at smaller scales.

Purpose of the Study:

• To investigate the fluid dynamics of urination in small insects.
• To challenge the existing paradigm that limits fluid jetting to larger animals.
• To develop a unifying fluid dynamics scaling framework for urination across taxa.

Main Methods:

• Dimensional analysis was employed to develop a scaling framework.
• The study focused on the fluid excretion capabilities of cicadas (weighing approximately 2 g).

Main Results:

• Cicadas demonstrate the ability to jet fluids through very small orifices, defying previous assumptions.
• A novel, unifying fluid dynamics scaling framework was established.
• This framework successfully accommodates a wide range of animals, from insects to mammals.

Conclusions:

• The findings expand the understanding of fluid excretion mechanics beyond mammals.
• The study highlights the potential for jetting in small organisms previously thought incapable.
• The developed framework has implications for ecology, evolutionary biology, and biofluid dynamics.