Evening star., 1953-08-19
Navy Probes Carpet
Of Fish in SEQ Depths
Minute Organisms Pose
Marine Biology Problem
By Thomos R. Henry

Science may be close to solving the
I0year-old mystery Of the seas, false
bottoms.
First discovered during the war, they
constitute one of the major problems
If marine biology
At depths Of between 1000 and 1900
feet in all the seas is a layer about
300 feet thick of super-abundant life
creatures Of some sort from whose bod
les sound echoes are returned. There
must be, it has been calculated, from
10 to 20 Of these organisms in each
cubic meter of water. They have been
a nuisance, although never a peril,
to navigation. High-frequency sound.
such as is used in depth-finding, passes
through them like light through q
window and finds the real bottom.
This great carpet of living things
lies, during the day, just below the
farthest point at which sunlight pene-
trates sea water. At best, the organ
iSms can be Illuminated by a dim,
green moonlight. Immediately after
dark the carpet rises, at a rate of 40
to SO feet a minute. to within few
hundred feet of the surface.
Evidently the animals cannot endure
anything but the faintest sort of light.
Matter of Conjecture.
The kind of creatures that make up
this zone Of Super-abundant life can
only be njectured-largely from the
frequency of the sound waves they
echo. Three theories have been ad-
vanced-that they are tentacled squid.
close relatives of the giant molluSkS
Of the North Atlantic; that they are
small, light-bearing fish; that they are
small, luminous shrimp. Each school
has its proponents, but most recent
Investigations indicate that there may
be a mixture of all three.
Considerable light has been thrown
on the mystery by joint Investigations
of the Navy. Electronics Laboratory
and the ScrippS Institution of Ocean
ography. Working with new tech
nique he has devised, DR.. Victor c.
Anderson has collected evidence that
some of the creatures are commercial
sized fish, IL to 18 inches long. Re-
Gently Navy divers have SWum through
the surface of the layer at night. They
reported the presence of microscopic
animals in great quantities, but no large
fish.
DR.. Anderson's technique has made
it possible for the first time to get
echoes from single sound Scatterers.
A receiving hydrophone and an under
water spark gap, used as a source Of
sound, are both lowered to the depth
of the scattering layer and the nature
of the echoes received from the sound
is observed.
This technique indicates the size Of
the organisms, not their kind. But large
fish At best into the pattern of some Of
the echoes.
Squid Indicated.
The argument for squid has some
strong points in it's favor. These mol
luskS move by jet propulsion. They are
among the fastest moving animals in
the sea. They range in size from four
or five inches to two feet long. 1t is
known that enormous numbers of them
come to the surface at night. They are
able to rise rapidly because their bodies
do not have to be adjusted to hydro
static pressure, as would those of fish.
A major argument for the shrimps
is their known abundance on the sur
face at night.
The puzzle is complicated by the fact
that the false bottoms are found in all
the seas, including the deepest Ant
arctic. At places. the carpet of under
sea life seems continuous, at others
broken into large mats separated by
clear water.