Evening star., 1953-09-28
Perch Go to Sleep
On Bottom After Sunset
Wisconsin Scientists Use
ho-Sounder in Study
By Thomas R. Henry
go to bed at SundoWn.

Fish go to bed at sundown.
AS soon as darkness comes, at least,
they settle to the bottom of Wiscon-
sin lake and remain resting on the
sand until daybreak.
This is reported to the American
Association for the Advancement of
Science here by Drs. Arthur D. Hasler
and James r. Villemonte of the Uni
versity of Wisconsin. Their investiga-
tions were made primarily on lake
perch.
They used an echo-sounding device,
similar to the type used by the Navy in
determining the mysterious false bot
tom" of the sea, to locate perch schools.
They found that the most consistent
echoes were received fairly near the
shore about an hour before sunset.
Apparently the fish, which had been
foraging through the day in deeper
waters, were concentrating in shallower
water where they would spend the
night They settled lower as twilight
approached and their echo trace
blended finally into the bottom echo.
No evidence of their presence was dis
cernible on the instruments after
darkness set in.
Diver Observes.
A diver, equipped with an aqualung
and communicating with the boat by
microphone, descended to the bottom
at intervals just before and after SUM-
down on eight evenings. Pre-sundown
observations revealed the perch. six to
eleven inches in length, aggregated in
tight schools with eight to ten inches
ioNixyid1,olc Ac ln11O a fharA
was sufficient light for the diver to see
without artificial light the fish moved
in schools off the bottom.
After sundown the diver, aided by
spotlights, found the fish dispersed
along the bottom, resting with their
fins touching the sand. When dis
turbed by the light, or the currents set
UP by the moving diver. they would
move briskly few feet ahead and sink
to the bottom again. At daybreak they
rose, congregated in schools and moved
out towards deeper water.
1T might be postulated." says DR..
Hasler, that with approaching twilight
the perch accustomed to seeing one an
other, lose their tendency to school
when this is no longer possible. 1t also
is possible that this nocturnal quieScent
behavior could have survival value IN
escaping natural enemies, many OF
whom hunt for food at night and per-
ceive prey principally by vibrations re-
sulting from the latter's swimming
movements"
Mixed Up Cat.
A cat with it's left side on its right
side has just been reported to the
American Association for the Advance
ment of Science here.
Everything inside this animal was
found reversed when it was diSsected
in the laboratory, reports DIR. Thomas
D. Baer of Syracuse University. Partial
reversion in mammals. even men, is not
uncommon but this is one OF the few
cases ever reported in which the phe-
nomenon applied to every detail.
There was complete reversal in the
position of the heart. This, in turn.
reversed the positions of the heart
chambers. The major blood vessels
conformed to this shift. A correspond
ing reversal was found with the veins.
Liver also was reversed, the larger
portion being on the right side. The
bile duct passed it on the left side.
The pancreas was reversed end for
end to correspond to the general re-
versal of the abdominal viScera. The
spleen lay on the right side OF the
body. The left lung was larger, which
is quite the opposite Of the usual ar
rangement. Only the kidneys. says DIR.
Baer, seemed to be in normal position.