Sunday, June 16, 2024

Slipper Shells Invade Long Beach!


Sources: Wikipedia, Library of Congress, Bill Lucey, Long Island Soundkeeper; Jeffrey Levinton’s Marine Ecology Laboratory, ; Sandra E. Shumway, Ph.D., D.Sc., Department of Marine Sciences, UCONN; Tessa Getchis, Connecticut Sea Grant/UConn Extension, University of Connecticut; Susan Dunne, Hartford Courant;

By Barbara Heimlich


She sells sea-shells on the sea-shore.
The shells she sells are sea-shells, I’m sure.
For if she sells sea-shells on the sea-shore
Then I’m sure she sells sea-shore shells.

Victorian fossil hunter Mary Anning was the inspiration for the tongue twister ‘She Sells Sea Shells. ‘ It was originally a song, with words by Terry Sullivan and music by Harry Gifford, written in 1908, inspired by Mary Anning’s life. She did not sell sea-shells on the sea-shore, but fossils.

Shell pile of the common slipper shell on Long Beach
Social media has been taking note (O.K. complaining) about the “mountains” of slipper shells on Long Beach. If you go to Long Beach you will see millions of shells on the shoreline. The shells are oval in shape, usually about 4 cm (about 1 1/2 inches) long and have an obvious shelf inside. These are slipper shells of the common slipper shell snail Crepidula fornicata. Another, the eastern white slipper shell, Crepidula plana, has a white and very flattened shell and can be found attached to the insides of large whelk shells and occasionally horseshoe crabs.

Slipper Shells (Crepidula fornicate) is a species of medium-sized sea snails, a marine gastropod mollusc in the family Calyptraeidae, the slipper snails and cup and saucer snails. It has many common names, including common slipper shell, common Atlantic slippersnail, boat shell, quarterdeck shell, fornicating slipper snail, Atlantic slipper limpet and it is in Britain as the “common slipper limpet”.

Crepidula fornicata has become very abundant in the past few decades, and one can’t help but wonder if they are taking the place of surf clams, hard clams and soft-shell clams, which have been badly overexploited by clammers on Long Island Sound. Slipper Shells are native to the western Atlantic Ocean, specifically the Eastern coast of North America.

The mountains of slipper shells we see on Long Beach is rather sad (especially if you are a Crepidula), but Dr. Sandra E. Shumway, from the Department of Marine Sciences, UCONN, believes a natural phenomenon. I’ve seen it before and there is a beach here in Groton (Bluff Point) that has a massive collection of shells also. I’m told that pile used to be made up of mussel shells, now replaced by Crepidula. And everyone needs to keep in mind that this is not a ‘die off’ of Crepidula that was on shore, it is Crepidula washing on shore and dying. The sort of thing one sees in the aftermath of large storms – but there haven’t been any.

Is there a solution? Starting a shell pile seems like a start, would be better if a way could be found to return them to the sea.

In 2021 the Connecticut state legislature passed a shellfish restoration and recycling bill, and a working group was formed to develop regulatory (sanitary) guidance for shell recycling and a strategy to help facilitate shell recycling programs across the state.

According to Tessa Getchis, Connecticut Sea Grant/UConn Extension, decomposing shells return a lot of minerals to the system. “Every time we harvest oysters, we are losing shells. A reef can’t rebuild itself without those shells,” she said. “We have these beautiful reefs but whenever we have rain it runs off land and plumes of sediment flow down our rivers. If we’re not adding shells to those beds they quickly get smothered.”

Smothered reefs can kill adult oysters and prevent baby oysters from settling into the reef. Reef damage also hurts living spaces used by sea creatures and feeding grounds used by birds, she said.

The shell recycling programs is beginning on the shoreline, where many seafood restaurants are, as well as those oyster reefs. “We have oyster beds from Greenwich to Stonington. The majority of the largest, most productive ones are from New Haven and west of that,” Getchis said. There is a private commercial scale enterprise in New Haven (Norm Bloom & Son) that recycles shell for its own use. There are also two pilot programs just starting up, in Groton (led by Zosia Baumann of UConn) and one in Stamford (led by Teisha Cole of Closed Loop Initiative Partners).

When a system is in place, it can expand to more northerly towns if seafood restaurants there want to participate, Getchis said. Participation by towns would be voluntary.

In January, CT Sea Grant Aquaculture Extension Assistant Michael Gilman was appointed as the state’s shell recycling coordinator. Though presently targeting oyster shells, the shell recycling is working to have towns develop plans for all shells.

Long process:
Returning shells to the Sound is not as easy as it sounds. Oyster shells can’t just be thrown back into the water after they’re eaten. There is a process, which if ignored can do more harm than good, Getchis said.

Shells must be dried and cured in open air for at least six months. Getchis said the reason is many Connecticut restaurants’ raw bars serve seafood that is not from Connecticut.

“They’re served raw right from the water. If we threw those shells back in to water it could introduce all sorts of problems: oyster diseases, organisms attached to the shells that you don’t want here, pests and predators,” she said. Also, the remains of what the shells interacted with — primarily condiments — need to be hosed off, then thoroughly dried, so that all trace elements flake away.

Finding a drying field that is big enough and well situated is not easy, she said, necessitating a collaborative approach between the state and the towns, which is made more effective if multiple restaurants jump on board.

Getchis said seashells that are thrown away wind up in a variety of places. Some end up in in-state landfills. Some wind up in out-of-state landfills.

Others wind up being collected by landscapers to pave driveways. “Although that’s a more environmentally friendly way — using shells for a driveway, instead of using tar — we want to get the shells back in the water where they belong.”

The new program is inspired by a program that launched in Fairfield seven years ago. Since it was founded, it has collected about 80,000 pounds of shells from, at any given time, two to six participating restaurants. A raw-bar caterer and the Milford Oyster Festival also participate.

John Short helped found the all-volunteer Fairfield program as an extension of the town’s Shellfish Commission, which is part of the municipal Conservation Department. Short interviewed the managers of similar programs in other Atlantic states before organizing the program.

Timothy Macklin, vice chairman of the Fairfield Shellfish Commission, who oversees seashell recycling, has started a nonprofit called Collective Oyster Recycling Restoration.(CORR) helps towns who want to recycle seashells but don’t have the capacity to do it alone.

“The biggest issue towns have, he said, is finding a storage space for curing. Finding those sites is challenging. We are fortunate in Fairfield we have an ideal site to do that. Others towns don’t necessarily have that,” he said. “We thought to store shells in town transfer stations, but based on current regulations that can be challenging because they’re only allowed to stay for a few days.”

CORR is working with Getchis and Gilman to make each of their efforts more efficient.

After they are cured in that area, shells are taken out to the reefs before the early-July spawning season. Timing is key, Short said. If they are deposited more than two weeks before spawning season, the placement will backfire.

“You don’t want them to sit too long or they will get fouled by silt. Fouling means the spat (oyster larvae) won’t catch as well,” Short said. “Clean, cured shell work very well. To the spat it’s almost like a magnet.”

Short said since the program began placing shells in the Ash Creek wetland and Mill River estuary, “there are many, many more oysters there.”

If you look out on the sand flats you will find thousands of live slipper shells. If you look closely you will notice that they occur in a stack of 2-5 individuals, usually, with the bottom one attached to a small rock. The stacks tell you much about their life history. The bottom individual is larger than the ones at the top of the stack and is inevitably a female, but the top individuals are smaller and males.

What is not obvious, is that every individual common slipper shell starts life out as an immature snail, then matures into a male, then loses the male function and matures into a female! If a new slipper shell comes on top of the first and lowest animal in the stack, it will have male function (copulation occurs by means of a penis), until another individual comes on top of him. He will then change sex to female function. Sex change, therefore, is not precisely timed but depends on the presence of other individuals in the stack. (Probably banned in Florida!!!)

Slipper shells are snails, but they are unusual. Their very large gills are covered with a layer of mucus. This layer traps phytoplankton particles in the water and the material is transferred to the edge of the gill and gathered together eventually to be eaten. They therefore feed in more or less the same way as mussels and clams.
A Slipper limpet stack are held together by the muscular foot at the bottom of each animal. The stack curves slightly; there is no need to balance in the water because they are nearly buoyancy-neutral.

The sea snail has an arched, rounded shell. On the inside of the shell there is a white “deck”, which causes the shell to resemble a boat or a slipper, hence the common names. There is variability in the shape of the shell: some shells are more arched than others. Groups of individuals are often found heaped up and fastened together, with the larger, older females below and the smaller, younger males on top. As a heap grows, the males turn into females (making them sequential hermaphrodites).

Crepidula fornicata is a species with cosmopolitan distribution, and can tolerate a wide range of environmental conditions, populations are particularly well developed in wave protected areas such as bays, estuaries or sheltered sides of wave exposed island, e.g. Long Island Sound. They are often found living stacked on top of one another on rocks, on horseshoe crabs, shells and on dock pilings.

What Can We Do:
Stratford has several commissions and boards that you can reach out to that hopefully would be interested in initiating such a program: Conservation Commission, Long Beach West Blue Ribbon Commission, Housatonic Estuary Commission, and Shellfish Commission.
Getchis is set to present a talk about the oyster bed restoration project. “Ensuring the Future Viability of Connecticut’s Natural Oyster Beds,” which also will have UConn Marine Sciences Prof. Zofia Baumann, is April 4th at 7:30 p.m. in the auditorium at UConn’s Avery Point campus, 1084 Shennecossett Road in Groton. Admission is free. Virtual access:


  1. We walked Long Beach yesterday and saw all those slipper shells and the amount of shells is unbelievable. They make it difficult to walk on the beach.

  2. Very interesting article. I have been going to Long Beach for 57 years and never knew the name of those shells. Now I can pass this knowledge to my 16 year old daughter

  3. I need a srrviceto help me “Clean up 5000 pounds of slipper shells. I need equipment I need somebody to help me move these things. Happy to use these to rebuild necessary jetties in front of mine and my neighbors houses… Whatever would be environmentally beneficial. Is there a service that can help me with this willing to donate or sell for other usages, but I cannot find anyone or any organization so far that offers what I am in need of. Thank you for any help. You can provide any suggestions. Welcome, Connecticut shore.

    • Amy I suggest you call Public Works and get permission to remove the Slipper Shells; I have no suggestions on who to call to haul them to your house.

  4. I would love to edit and correct spelling on my previous posting… Does not seem that there is an opportunity to do that, but I hope everybody can get the general just again. Thankful for any suggestions and help.


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