No. 37–Questions and Answers

Q. I recently saw the remains of a fish when the tide was out and it was covered with little black snails. What kind were they and what can you tell me about them?

A. They were eastern mud snails, Ilyanassa obsoleta. They are found throughout our marshes wherever there is, what else?, a mud bottom. They are omnivorous feeding on detritus, algae and anything dead they happen across. Unlike most snail species with individual animals leading largely solitary lives, mud snails like company and leave a mucus scent trail which serves to keep a group together. If you see a single animal with no others near, it has either wandered off and become terribly lost or it is injured. The group can detect the scent of an injured or dieing individual and will abandon it to its fate.

Intertidal oyster drill snails Urosalpinx cinerea may be found in close proximity to each other but that is more a function of their prey, juvenile oysters, being clustered than any sense of community amongst them.

Q. We have just moved here from Arizona so all of this is new to us. My boys have been playing on a creek nearby and are fascinated by comings and goings of the tide. They want to know why some tides are higher and lower than others.

A. The short answer is that tidal height variations, though wind direction and strength have some influence, are largely due to the cycles of the moon. The periods of the new and full moons give us spring tides with the highest highs and lowest lows and the neap tides of the quarter moons give the lowest highs and highest lows of the lunar month. Go to “Curator’s Corner” on our website below and click #20 The Tides for a fuller explanation.

I don’t know the size or topography of the creek your boys enjoy but please caution them not to cross to the opposite bank or explore mid creek sand bars or oyster rakes on low tide, they can become stranded by rising water if they’re not paying attention.

Q. Our kids were really taken by the diamond back terrapins on our visit to the Estuarium this summer. Now that it’s gotten cold they’re wondering how terrapins in the wild get through the winter. They also want to know if yours will have babies.

A. They hibernate. They bury into the creek mud where they can remain for extended periods, months in the case of more northern populations, without eating or breathing. I’m hoping that Greta and Stash will have babies when they’re mature in about three years. Hopefully we will have built our permanent facility with a dedicated terrapin habitat for captive breeding and release program by then.

Q. I’m new to the area and attended an oyster roast with friends. While your local oysters are a little more work than the restaurant singles that I’m used to, they were the tastiest I’ve ever had. What makes them so special?

A. We do like to think we have the best tasting oysters in the world. It’s largely due to the high salinity of our estuarine waters.

Q. I caught a fish that had bug like things attached to its gills. They moved when prodded with a knife and one dropped off to the bottom of my boat. It looked like a flattened roly-poly. What the heck are they?

A. The relatively small (2.5 cm or less) crustaceans of the class Branchiura are commonly known as fish lice. There are 75 known species world wide inhabiting both fresh water and marine environments with a small number of species found locally. They are parasitic feeding on the blood or mucus of the host and are free swimming with the ability to move from one host to another. Depending on the number involved and duration of stay an infestation may be but is not always fatal to the host.