BlO—Lancaster Farming, Saturday, November 3,1984
Diver off the east coast of Australia encounters a giant clam
about 3.5 feet long. The excurrent siphon (hole in fleshy part)
expels water and waste" Sought for their shells are disap
pearing in many parts of the hope to check
their decline through aquaculture.
w
BLACK
6(&Y
Ok.6R£Y
BLUE
BROWN
BABOONS : 7b£Y3£Lotf6 To
ft GROUP Of mammals CPU
EPPR/MftTES, TftamME SUG
GESTS TftftTTH£&ft3ooM/5>
ft PR/MB OPTDPftM/MftL.
THEYRftTB TH/SPOST/OUdB
CRU6B THEY ftߣ VERf///TEE
U6EKTMTU U/EU PEI/ELOPED
PRft/NS, THEY NAME STROKE
POLUeftPUC TEST//ft//P A
Fierce D/sposmoM ru/s
MAKES /TP/FE/CUCfTP
CAPTURE 7NEM.
PEACH
GREEN
LT BROWN
LT. BLUE
LT GREEN
Giant clams threatened by predation
“They’re the gentlest of
creatures," says Richard L.
Radtke, a marine biologist at the
University of Hawaii "There's
never been a documented case of a
giant clam devouring a swimmer
or even grabbing an unsuspecting
victim long enough to cause a
drowning.*'
Radtke should know. He's been
studying giant clams at Rose Atoll,
a remote chunk of coral about 137
miles east of American Samoa.
The atoll is protected as a wildlife
refuge and is so isolated that it is
one of the few places in the world
where thousands of giant clams
can still be found in a relatively
confined area.
The giant clams and the oc
casional sharks that nose about are
the least of Radtke’s worries. A
victim of multiple sclerosis, the
scientist gets around mostly in a
wheelchair. But that doesn’t stop
him from donning scuba gear to do
his underwater research.
“The water’s a great equalizer,”
explains Radtke. “The freedom I
have beneath the waves helps
make me view my affliction as
more of a nuisance than a tragedy.
It’s an incentive to find different
ways to do things and pursue my
research.”
Such determination has enabled
Radtke to work in places far less
congenial than the South Seas.
He was the first legally han
dicapped scientist chosen by the
National Science Foundation to do
a project in Antarctica. He hopes
to return there this year for
another field season.
Radtke’s work with the giant
clam, Tridacna maxima, has
already turned up some major
o
WASHINGTON - Giant clams
don’t deserve their reputation as
man-eaters.
DIVES DESPITE HANDICAP
surprises. Examining the hinges of
the creatures with a scanning
electron microscope, he
discovered minute laminations. He
suspects these markings, which
look like curving lines when
magnified, may be added an
nually, much like the rings that
mark a tree’s growth.
Microscopic, straight-line
laminations inside the valves or
shells seem to occur daily.
Based on these findings, Radtke
estimates that the clams reach
their biggest size, about 16 inches
long and 15 pounds, when they are
about 16 to 20 years old, their
maxftnumage.
AID TO CONSERVATION
By determining the age, growth
rates, and interaction of clams in a
relatively undisturbed en
vironment, Radtke hopes to gather
information that will aid giant
clam conservation efforts.
There is some urgency to his
work, because both local and
federal government officials are
anxious to know whether the clam
population at Rose Atoll is secure
enough to be harvested.
His information would also be
useful in many other parts of the
world where giant clams are
threatened with extinction.
Especially hard-pressed is the
heavyweight of the species,
Tndacna gigas, which can weight
more than 500 pounds, measure
more than three feet long, and live
50 years.
People of the Indo-Pacific prize
the giant clam for its meat. They
sell the shells as curios and
souvenirs. The World Wildlife
Fund reports that the shells also
are being used in the manufacture
of luxury floor tiles.
One hope for the future may be
clam farming, already started
experimentally at a manculture
station on Palau m the Caroline
Islands. There, mature clams are
left in a large tank to spawn
naturally.
After fertilization, eggs hatch
into larvae that settle on a hard
surface. They need only sunlight,
clean seawater, and protection
from predators. No feeding is
required.
The tiny clams initially filter
food from the seawater, but as they
grow they depend more and more
on minute algae called zooan
thellae. These live in the cells of
the clams’ distinctive wavy
mantles and use sunlight to
produce nutrients by photosyn
thesis. Once the clams become
large enough, they can be planted
on reefs to grow in the wild.
“What a dream crop,” says
Radtke. “It doesn’t move, it
doesn’t eat; it just sits there and
soaks in the sun.”
Golden Guernsey
4-H Club
The final meeting of the Golden
Guernsey Dairy 4-H Club was held
at the home of George Rohrer on
Oct. 23. The group had a business
meeting followed by a Halloween
party with games and tricks.
The group gave special thanks to
their leaders Peter Witmer and
Gerald Garber for their hard work
and dedication throughout the
year.