Essay/Term paper: Penguins

Essay, term paper, research paper:  Science

Myopic little men in tuxedos, or highly efficient
land/water animals? Recent research indicates
there's more to penguins than meets the eye. If
you've every wondered what it would be like to
be able to see as clearly under water as you can
on land, just ask the nearest penguin.Most aquatic
animals are short-sighted on land. Most terrestrial
animals (and that includes us) are far-sighted under
water. But researchers have discovered that
penguins can apparently see equally well in both
environments, because of the unique structure of
their eyes. Penguins have to be able to see well
under water because their diet consists mainly of
plankton, molluscs, crustaceans, and the inevitable
fish. Through a special slowing-down of their heart
rate they're able, like many other diving animals, to
stay submerged long enough to search out and
chase whatever catches their fancy. On dry land,
it's a different story-or has been up to now.
Waddling along on their flat little feet, eyes fixed
intently on the ground, penguins appear myopic,
inefficient and generally out of place. In fact the
reverse is true. During a recent stay on the
Falkland Islands, a Canadian researcher
discovered that penguins are able to recognize
individuals and navigate the rocky terrain on which
they live quite well. Long of body and short of leg,
they probably poke their heads forward as an aid
to balance. And as for looking at the ground,
they're merely-like us-keeping an eye on where
they're going. The human eye is adapted for aerial
vision, which is why scuba divers-or even you and
I in the local swimming pool-must wear goggles or
a face mask to re-introduce air in front of our eyes
in order to see clearly. Among vertebrates in
general, the bird eye is frequently described as the
most efficient. Its superior quality, combined with
the fact that a large number of birds-cormorants,
pelicans, seagulls, even ducks, as well as
penguins-get their food from water, obviously
deserved research beyond that possible in a
controlled environment such as an aquarium or
zoo. Professor Jacob Sivak of the University of
Waterloo and his associate, Professor Howard
Howland of Cornell University, had a chance to
do that research recently. Their trip had but one
purpose-to study the structure of penguins' eyes
while observing their natural habitat. The Falkland
Islands, off the coast of Argentina, offered this
opportunity, being one the few areas outside
Antarctica where penguins can be found in large
numbers. Three of the 16 known species were
located there: the Gentoo, which live on flat areas
right off the beach; the Magellan (also called
Jackass), which live in burrows; and the
Rock-hoppers, which live among the rocks along
the cliffs. The Rock-hoppers were by far the most
common, having a population of well over
100,000. The general rule is, the smaller the
penguin, the meaner the temperament, and the
researchers did witness the odd fight. Their
flippers may look pretty useless out of water, but
it's not smart to play around with a penguin. Hel'll
stand his ground in a face-off and if you're foolish
enough to get too close, those flippers can knock
you flat. Dr. Sivak and his associate, however,
had little trouble. Rock-hoppers always
congregate in fairly tight groups, as a defense
against predatory birds such as the skua (a large
seagull that thinks it's a hawk), and two more
upright figures in their midst didn't seem to bother
them. Standing as close to their subjects as 0.3m,
the scientists used two devices: one, developed by
Professor Howland, to take photographs of the
penguins' eyes; the othger, developed by Dr.
Sivak, to shine a series of concentric circles on the
cornea and give a measurement of how reflections
of objects are altered by curvature of the eye.
Despite the fact all the work had to be done at
night-the only time the penguins' pupils were
dilated enough-the results were worth it.
Comparison of the photographs with similar
photos of human eyes, and study of the internal
structure of the eyes of creatures discovered killed
by seal lions, proved the scientists' theory that the
penguin's eyes are the secret of its survival. In
general terms, a penguin eye and a human eye are
almost identical. Both have the same components
necessary for vision-a cornea through which light
can enter; an iris which controls the amount of light
that enters; and a crystalline lens that focuses the
light onto the back of the eye where a specialized
membrane, the retina, receives it and passes the
message along the optic nerve to the brain for
interpretation. In the penguin eye, hoever, there
are many subtle differences. The cornea, for
example, is markedly flattened compared to ours
-- so much so that it almost resembles a
window-pane. This greatly alters the angle at
which light can enter the eye and is very important
for underwater swimming, when light enters the
eye obliquely through a medium (water) whose
density is quite different to the density of air. The
penguin iris is controlled by a very powerful
muscle which is able to drastically alter the shape
of the lens attached to it, depending on whether
the penguin is in or out of the water. The lens,
comparatively larger than ours and differently
shaped, focuses the light coming through the
flattened cornea onto the retinal body at the back
of the eye. In this way, the penguin eye adapts to
whatever medium it happens to be in at the time.
Interestingly, there was no evidence of eye
problems (apart from one incident of blindness
due to injury) in the group of penguins studied. Of
course penguins don't read, watch TV or
encounter any of the numerous irritants we
land-bound animals subject ourselves-or are
subjected-to during our lifetime. Both the testing
devices and methods used in this study are easily
adaptable for use with human eyes, paving the
way for fast, easy identification of eye problems.
Also, the researchers hope that the insights they've
gained into how animals deal with two
environments may lead to knowledge of how
humans, in the future, might do likewise.