Sea shell

Early Morning Slipper Shell Tide Walk

Last month my son and I caught a great tide and were up before the sun to head out along the beaches in search of some periwinkle snails. He and his siblings had been making a good bit of money all summer picking snails for the local buyers. These are commonly known as 'Escargot' but locally known as 'rinkles'. Noone eats them here - they are trucked south to Boston and Providence to customers there. Call them what you want - our kids were making $10 - $30 for an hour or two of work picking snails at low tide on the beach in front of our house. Great work for them; they have to be up early, traipse across the mud, and bend their backs carrying the heavy pails of snails back to our yard. A great life lesson.

Back to our snail walk... it was a rather cold morning with a Northwest breeze blowing, but it did warm up quickly as the sun broke the horizon. The sun made for a great picture as it crested our local Osprey nest.

We quickly realized that another harvester had cleaned up all the snails along this particular beach - probably the day before. What we did not realize was that there would be such a great supply of Common Slipper Shells!

Slipper Shells are actually a kind of snail related to whelk snails and periwinkles. They are Molluscs and are in the class Gastropoda. In some places they are called 'Boat Shells'. They get their name from their shells. If you find one of their shells in the beach it has the unmistakeable look of a slipper! They have a rosy color on the topside but underneath you will find a creamy white - mother of pearl type coating. They are kind of pretty!

Slipper shells are filter feeders so they are not cruising around on the rocks like Periwinkles or Limpets - they avoid all that competition. On this particular beach they are using the great supply of old sea scallop shells as a place to live, feed, and of course breed! Since they have such a strong 'foot' they can stay in one place attached to a rock or a scallop shell while taking advantage of the tidal currents and the food that is carried to them. To feed they simply relax their foot, open a gap between the substrate and their shell and let that food enriched water feed them to their hearts content!

The most interesting thing about these little invertebrates is that they can change their sex from male to female to male and so on. They have a great system going for making new slipper shells (babies). Unlike some Molluscs that just shed eggs and sperm into the sea water in the hopes that they will mix and form embryos, the slipper shells actually mate. To do this, they need to be in close proximity. They form a 'pig-pile' - it is great fun for them. The most we have seen in a pile is 6 shells! The largest slipper shell is at the bottom and the smallest at the top - kinda like a snowman. The bottom shell in the pile is the female. Males will attach to a female or to some other substrate such as a rock or old scallop shell. In this case, the male will turn into a female and then secrete a chemical into the water to attract a male! If the female at the bottom of a stack dies then each successive slipper shell in the stack must change sex from male to female and vice versa. What a life!

So my son did not make any money on this morning, but we did have a great father-son hike on the beach. We found some huge Northern Sea Stars (Starfish) - 16" across like this:

Much to our surprise, we also found a big gelatinous gob of squid eggs attached to a rock right at the tideline! Great find!

There were some live Sea Scallops on the beach here and there. They are fun as they clap their shells and spit water sometimes. Our local bay grows some beautiful sea scallops. This is due to the fact that we have such huge tidal currents and nutrient rich waters supporting lots of plankton (scallop food). Scallop fishing season is during the winter and spring. Local boats will land 120 lbs of scallop meats each day - this is about 3 - 5 gallon pails of meats - wow!

Humans always like to learn about how particular species relate to people. I am not quite sure how a slipper shell affect us. In some places oyster farms consider slipper shells pests. They attach to the shells of oysters and compete with them for food. I personally have never tried eating a slipper shell - but it does make sense that they would be pretty tasty. I do eat snails, clams, oysters, mussels, and scallops so why not slipper shells? Maybe next time I get some I will give them a try!

If you want to find slipper shells on a beach walk or in a tidepool here is my advice. It will be best to do your collecting during spring tides. A slipper shell is essentially a 'sub-tidal' organism and it does not really want to be left high and dry by the receding waters. Look for slipper shells on the sides of rocks - not the top. They tend to be on the bottom of shells. They like to keep a low profile - out of sight out of mind - perhaps to prevent getting eaten...? Not sure.

If you are looking for some slipper shell specimens - give us a call at Gulf of Maine, Inc., www.gulfofme.com. We will collect you some fresh, live slipper shells and ship them out to you immediately. We are happy to get you the lab, classroom, and project samples you need, when you need them. Our biological supply company works hand in hand with some of the largest college biology programs, aquariums, and research institutes in the country!