Oyster Drill

Colloquial Nickname: Thick-lipped Oyster Drill, Atlantic Oyster Drill Scientific name: Eupleura caudate, Urosalpinx cinerea

Color: Dull brownish to grey shell with white points Habitat: Sea grasses, oyster beds, intertidal rock bottoms Size: Thick-lipped Oyster Drill - up to 3/4 inches long, Seasonal Appearance: All year Atlantic Oyster Drill - up to 1 inch long

DISTINGUISHING FEATURES AND sulfuric acid to carve away the shell and make the hole. Once the BEHAVIORS hole is made, the animal will digest the soft meat of the prey. Oyster drills are small predatory snails found in Narragansett The mark left by an oyster drill can be identified as wide, Bay. round holes tapering to a small The Atlantic oyster drill and the point in the shells of mollusks. thick-lipped oyster drill are the two This is similar to the holes made species most common in the Bay. The by another predatory snail called shell of the Atlantic oyster drill is ribbed the dog whelk, but is different from with a pointed spire, a flared outer lip the many pock-mark holes by with two to six teeth along the opening, boring sponges. and many rough and raised whorls and longitudinal ridges on the shell. RELATIONSHIP TO The thick-lipped oyster drill is PEOPLE similar to the Atlantic oyster drill, but Oyster drills are one of the the anterior canal is longer with a worst enemies of small oysters, smaller opening. This oyster drill full-grown clams, oysters, other resembles a small whelk or conch, with bivalves, and even barnacles. distinct channels of shell. The outer lip Oyster drills and sea stars can is thick with no flare and has six distinct create serious problems for teeth. commercial and recreational The egg capsules of these snails can be found in spring and shellfishing. When oyster drills occur in great numbers, they early summer. The eggs are small, urn-shaped, leathery cases can decimate whole oyster and clam beds. generally found attached to pilings or mollusk shells. Oyster drills are destructive little snails that prey directly on HOW TO GET YOUR OWN COPY small shellfish, most notably oysters. The oyster drill attacks its RISAA members can purchase their own copy of The prey by making a small hole through the shell, using a drill-like Uncommon Guide To Common Life on Narragansett Bay organ called the radula. The radula is aided by the secretion of for $15 from the RISAA Merchandise Committee. Stop by the committee table at any monthly RISAA meeting.

- 30 - R.I.S.A.A. / May, 2017