Evening star., 1938-09-04
NATURE STUDIED
FOR CAM0UFLACE
Science Turns to Animal
Kingdom for New, Less
Clumsy Methods.
BY THOMAS r. HENRY,
Star Staff Correspondent.

Star STAFF Correspondent.
CAMBRIDGE, England (By MaiD -
Science is turning to birds, insects and
fishes for new methods of camouf1age
to replace the clumsy tricks of World
War days which now would not fool
the stupidest enemy observer.
The animal kingdom has chest
full of DISCUSSES hitherto unsuspected.
evolved In the eternal warfare of life
In the wild, according to an exhibit
before the British Association for the
days ago.
One thing the World War strategists
didn't think about very much was
infra-red photography from airplanes
The frogs thought about it countless
generations ago. it appeared from the
exhibit, and took measures to protect
themselves from the infra-red sensi-
tive eyes of some of their swooping
enemies
Ordinarily when the picture of
landscape Is taken with infra-red light
the result Is a ghost-land scene with
all the trees and bushes an eerie white.
This is because chlorophyl, the green
pigment in leaves, reflects all infra-
red rays. Anything that absorbs them
appears black in the white landscape.
Camouf1age accomplished with some
material which did not reflect these
rays would defeat its own purpose
and the object supposed to be hidden
would stand out very clearly against
the ghostly background.
Animal Pigments Absorb Rays.
Most animal pigments intended for
concealment, 1t is shown by the exhibit
arranged here by DR.. H. B. Cott of
the University of Glasgow, have this
infra-red absorbing capacity, especially
if their natural enemies have eyes
sensitive to this invisible light 1t has
been developed presumably by process
of survival of the fittest through mil
lions of years. The enemies, on the
other hand, have developed sensitivity
to lnfra-red in the same struggle for
existence, those possessing it in the
greatest degree being able to get more
to eat. The frog was shown as an
especially fine example of an animal
which remains as invisible as its sur
roundings in an infra-red photograph.
Another trick of camouf1age found
by DR.. Colt highly developed in some
birds and many insects is that of a
sharp contrast of colors. Superficiallv
this seems to make the creature more
conspicuous, Actually, as photographs
show, it conceals it altogether One
color harmonizes with the surrounding
landscape so that it seems merely a
continuation of it. The other is in as
striking a contrast as possible. The
result is that what the hunter sees is a
very sharp pattern of glaring color
which has not the slightest resem-
blance to anything it wants to eat and
1t passes on without any attempt to
investigate.
Fish Looks Like Dead Leaf.
From all over the world DR. Cott
has gathered examples of animal
camouf1age perfected through millions
OF generations of evolution. One strik-
ing case was that of the pache de
fohla, a fish of the quiet waters of
the lower Amazon. 1t has evolved not
only the appearance of a dead leaf
but swimming habits which simulate
almost precisely the drifting of
Water-logged leaf in a stagnant pool.
This camouf1age is both for defense
and oftense, for the water insects
which are its prey approach it with
out any suspicion. In striking con-
trast is another fish from Ceylon.
also camouf1aged to look like a leaf.
But this fish happens to live in swift
water, so its swimming habits simu-
late very closely the motions of a leaf
tossed about on A current,
One OF the best of the leaf camou-
hages collected by Dr. Cott is that of
South American toad. 1t is a slug
glsh creature living amidst dense
foliage which it resembles very CLOSELY
in color. But when one looks through
interstices in foliage there are shadows,
II these are not found. a bird of prey
might sense that something was wrong
and investigate. So on the back of
thls toad are black spots of precisely
the shape and hue which one would
expect in such shadows. Its remark
able camoufage is this creatures onlv
defense and on the rare occasions
when it is detected it can do nothing
but play dead.
Green Beetle Is Strangest.
Leaf Stimulating insects are common,
but DR.. Colt found the strangest of
all in green beetle which not only
looks like leaf but which hangs from
twlg by two legs and spends its
Whole life sWaying gently back and
forth like a leaf in a gentle breeze.
Another strange creature is an Al
gerian ''grasshopper," which lives in
the barren desert. It's color har-
monies precisely with the rocks
around it, but in the bright sun there
would be danger of detection by the
sharp eyes of soaring birds from the
tiny shadow which would be cast by
its body So it is provided on both
sides with fringes of hairs to neutral
lze such shadow
Also we'll known are insects which
have a barkllke appearance providing
very good camouflage because they
ordinarily are found on tree trunks.
But in several species studied by the
Glasgow biologist the precision of IN
stinct has gone much further. One
such insect always alights vertically
on the tree trunk SO that it is per-
feet alignment with the grain of the
bark. Another closely related species
has an appearance which blends with
the horizontal pattern of the bark and
consequently invariably lands in
horizontal position in which it is al
most perfectly concealed.
New Fishing 1nra