|
Oyster drills are small
predatory snails found in Narragansett Bay. The Atlantic oyster
drill and the thick-lipped oyster drill are the two species most common
in the Bay. The shell of the Atlantic oyster drill is ribbed with
a pointed spire, a flared outer lip with two to six teeth along the
opening, and many rough and raised whorls and longitudinal ridges on
the shell. The thick-lipped oyster drill is similar to the
Atlantic oyster drill, but the anterior canal is longer with a smaller
opening. This oyster drill resembles a small whelk or conch, with
distinct channels of shell. The outer lip is thick with no flare
and has six distinct teeth.
The egg capsules of these snails can be found
in spring and early summer. The eggs are small, urn-shaped,
leathery cases generally found attached to pilings or mollusk shells.
Oyster drills are destructive little snails
that prey directly on small shellfish, most notably oysters. The
oyster drill attackes its prey by making a small hole through the
shell, using a drill-like organ called the radula. The radula is
aided by the secretion of sulfuric acid to carve away the shell and
make the hole. Once the hole is made, the animal will digest the
soft meat of the prey. The mark left by an oyster drill can be
identified as wide, round holes tapering to a small point in the shells
of mollusks. This is similar to the holes made by another
predatory snail called the dog whelk, but is different from the many
pock-mark holes by boring sponges.
|
