Question of the Week: Why did an oyster drill kill a naked goby?

Welcome once again to the BayBlog Question of the Week! Each week we'll take a question submitted through the Chesapeake Bay Program website and answer it here for all to read.

This week’s question comes from Rodney. Rodney told us how he had a saltwater aquarium with an oyster drill, a small oyster and a naked goby living in it. One day, he found the oyster drill attached to the goby and when he separated them, the goby was dead.

He asked, “Have there ever been any studies of an oyster drill actually catching and killing small fish? The oyster drill attached itself to the oyster, but never actually drilled or ate the oyster. Why is that?”

After doing some initial research into this interesting occurrence, we couldn’t find any other documented incidents of an oyster drill feeding on something other than an oyster. We sought further advice from Dr. Roger Mann, professor of marine science and director of research and advisory science at the Virginia Institute of Marine Science (VIMS) at William & Mary.

“While this is very unusual, I would not be completely surprised by such action,” Dr. Mann wrote. “Oyster drills are predators and will take available prey.”

He explained that the mouthparts of predatory gastropods are species specific and that those of oyster drills are designed for “rasping through shells, then devouring the meat of the prey.” But they could still be used for eating tissue of fish. Other gastropods, such as some cone shells, have mouthparts designed specifically for mobile prey like fish.

“As to why the drill never ate the available oyster, it probably was not hungry enough, especially if it has an easy meal in the goby,” he said.

This instance proves that while most species are creatures of habit, they will often do whatever is necessary to survive. To learn about more interesting creatures and critters in and around the Chesapeake Bay, check out our Bay Field Guide.

Do you have a question about the Chesapeake Bay? Ask us and your question might be chosen for our next Question of the Week!