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crazyfrog
Kermitologist
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Joined: 31 May 2003
Posts: 7610
Location: atlanta
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 Posted: 10/26/05 - 16:34 Post subject: penguin poo
an excerpt from an article for next weeks journal club in my department:
| Quote: | Penguins spend most of their life in the water. An extended
period ashore only occurs during breeding.
Anyone who has then watched a penguin fire a ‘‘shot’’
from its rear end must have wondered about the pressure
the bird generates, but apparently no published
data on the pressures produced exist.
Brooding penguins, in order to relieve themselves, do
not leave their stony nest, but move to the edge of it, stand up, turn their back nest-outward, bend forward,
lift their tail, and shoot. The expelled material hits the
ground maximally 40±12 cm away from the bird and
then leaves behind a whitish or pinkish streak that can
end a few centimetres from the nests periphery and may
be up to 1 cm wide. The colour of the streak depends on
whether the penguin had enjoyed a meal of fish (mostly
white) or krill (pinkish). According to Jackson (1992),
the time required to excrete 50% of the total faecal mass
is 9.1 h and 14.5 h for fish and prawn food, respectively.
From a few ‘‘spot-on’’ photographs, we estimated the
aperture, from which the semi-liquid excretory material
is released, to possess a maximal diameter of 8 mm at
the moment of ‘‘firing’’. Hind-gut diameters of 4.2 mm
for the smaller rockhopper and 13.8 mm for the larger
gentoo penguin are on record (Jackson 1992). Although
the orificium venti generally opens through a horizontal
slit in the Spheniscidae, the orifice becomes circular
during evacuation (King 1981; Watson 1883). Since
penguins, prior to venting, ascend the rim of pebbles
that forms the edge of the nest, and are then somewhat
higher than their surroundings, we place the elevation of
the cloaca 20±6 cm above ground (Fig. 1). By adopting
average (=typical) values, we can mathematically
examine which pressures would have been needed to
achieve the faecal distances we measured around a
penguins nest. The model would then allow comparisons
between the ‘‘penguin-generated’’ pressures and
those other organisms produce in connection with the
propulsion of fluid or viscous material in narrow tubes,
e.g. urine, seminal fluid, blood and, of course, faeces.
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i think i might go to this one, it could be interesting.
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