Evening star., 1938-02-15
Natures Children
Oyster Drills.
BY LILLIAN cox ATHEY.

T TERE is a pair of foes that are
making lot OF trouble
among the oysters. The SCI
4 4 entific name for the first one
is Eupleura caudata and the second.
Urosalpinx cinerea. From Cape Cod
to Florida the oyster bottoms of the
coastal waters have myriads of these
small snails known among the OYSTER
men as drillers.
Many have been found on the
rocky shores of New England as well
as on the oyster bottoms Of Great
South Bay, Delaware Bay, lower Ches-
apeake Bay and seaside Virginia.
So serious were the inroads made
by these drillers upon the common
oyster that a special appropriation
was passed so that the United States
Bureau of Fisheries could make an
extensive and thorough investigation
Of the life story and ways of con-
trolling this aggressive army. The re-
search began April l, 1885. and lasted
until June 30, 1896. The facts that
came to light were startling. In Della
ware Bay alone it was found that the
drills destroyed more than 100000
worth of oysters each year. On the
Eastern Shore of Virginia, between
Chincoteague and Cape Charles, the
estimated loss was s15O,00O. While
an accurate figure would be impossible,
several million dollars annually are
lost through the work of these small
oyster lovers.
The drill is SO named because of
its special rasping organ, known as
the radula. It Is q ribbon-like film
which is covered with thousands of
tiny chitinous teeth, arranged in
rows. This radula, is on a flexible
membrane and is in the proboscis of
the driller.
This very efficient rasp works some
thing like a cats tongue when she Is
washing her face and feet or taking
her morning bath. The driller wish
ing to feast upon the tender oyster
attaches itself to its victim, and by
steadily boring or rasping the shell
finally enters it.
Perseverance is the ruling passion
OF the driller's life. To drill through
the heavy shell of an adult oyster
takes a long time. For the progress
made daily Is one-fiftieth of an inchl
The hardness of the shell, the size Of
the drill, the temperature of the water
and other conditions may also enter
into the story.
However, there comes a day when
the driller does find his labor has
not been in vain and the soft meat
Of the oyster Is sucked by the pro-
boscis after the driller's tongue has
reduced 1t to liquid. The wounded
oyster often relaxes completely or
dies from the injury, so that the shell
opens. Then may rush In those who |
have not gone to all the trouble the
driller has and help themselves to
the victim. and the driller has to be
satisfied with the little left.
Drillers move about like all snails,
for they are provided with q most |
muscular foot and it Is with the |
slime of this foot they cling to their |
victims.
The mother drill always creeps up
ward from the bottom Of the oyster
bed IN order to lay her eggs above the
line where there are too many foes.
The youngsters are then safer and
later they will 60 to the bottom to
for the winter in the mud
and sand. These creatures travel
always toward food. This accounts
for their wide distribution.
AS you can see, the egg cases Of
the drills are lovely. They are cream
colored, vase-shaped and leathery.
They are about one-fourth Of IN inch
long and are attached to rocks, shells
or other solid objects. You may md
them In April and as late - No
vember. /
tcssyu :. 1880