Pressures produced when penguins pooh

Serious scientific research papers can be funny. I cite selected passages and diagrams from this toilet-breaking research.

Pressures produced when penguins pooh—calculations on avian defaecation
Victor Benno Meyer-Rochow & Jozsef Gal
Polar Biol (2003) 27: 56–58

Abstract Chinstrap and Ade lie penguins generate considerable
pressures to propel their faeces away from the
edge of the nest. The pressures involved can be
approximated if the following parameters are known: (1)
distance the faecal material travels before it hits the
ground, (2) density and viscosity of the material, and (3)
shape, aperture, and height above the ground of the
orificium venti. With all of these parameters measured,
we calculated that fully grown penguins generate pressures
of around 10 kPa (77 mm Hg) to expel watery
material and 60 kPa (450 mm Hg) to expel material of
higher viscosity similar to that of olive oil. The forces
involved, lying well above those known for humans, are
high, but do not lead to an energetically wasteful turbulent
flow. Whether a bird chooses the direction into
which it decides to expel its faeces, and what role the
wind plays in this, remain unknown.

Model:

Penguin and the defaecation distances. Click on diagram for a larger image.



Results:

Viscosity of excrement, nature of sound and pressure exerted are compared. Click on diagram for a larger image.



Conclusions:

It is interesting to note that the
streaks of the faecal material radiate from the edge of
the nest into all directions (no preference is noticeable).
Whether the bird deliberately chooses the direction into
which it decides to expel its faeces or whether this depends
on the direction from which the wind blows at
the time of evacuation are questions that need to be
addressed on another expedition to Antarctica.

I'm glad somebody has been working on this important problem of penguin defaecation.