Wading in with Urosalpinx cinerea

As we pull into NYC on the Amtrack for a science filled weekend, Mrs. S's class in Rhode Island have gotten fully funded for their new waders as part of the Oceans in the Classroom Challenge. Hopefully they are thinking about getting in some clamming very soon! While they are out there wading in the beautiful coastal waters of Rhode Isalnd, they will no doubt see many Atlantic Oyster Drills as well since Urosalpinx cinerea is a pretty common sight around here (here being eastern Connecticut and Rhode Island). Unfortunately it is also becoming more common on the west coast in areas like Puget Sound where it is an invasive species, as well as being a nuisance to oyster fisheries on both coasts.

Even though it is a nuisance to mollusc fisheries and aquaculture, I can't help but like this particular carnivorous gastropod. It lives in the harsh intertidal zone, an area where it may well probably the most effective hunter. It "smells" out it's prey in the water: young oysters, young clams, or the thinner shelled blue mussels. Once located the one inch predator climbs onto its prey and grabs it firmly with its foot. Then the drilling begins.

Using its radula, a ribbon like organ with rows of tiny teeth on it, the oyster drill rasps away at the shell, scraping bits of the calcium shell. After rasping for a time the oyster drill brings out its secret weapon, the accessory boring organ (ABO). The oyster drills use of the ABO was described originally by Mel Carriker while he was a graduate student in the late 1930's early 1940's, we have featured his video and explanation of the drilling before (highly recommended!). Between 1 minute raspings with the radula the drill presses the ABO against the drilling site for 30 minutes, releasing calcium dissolving acid to soften the next layer of shell and make the drilling easier. Depending on the thickness of the preys shell, the process may take upwards of a day to complete. Yes the oyster drill is persistent!



Once through the shell the oyster drill inserts its proboscis through the hole and releases digestive enzymes into the prey shell ans slurps the resulting liquefied meat back up through the hole via its proboscis.



Another cool detail about the oyster drill is that unlike most other gastropods, the oyster drill does not have a planktonic larval stage. The oyster drill lays its eggs that each have up to 12 young in them under rocks and shells. The young snails eat their way out of the eggs and look like miniature adults.