The Littleneck Clam: A Little Shell With A Big Personality

The littleneck clam is a unique mollusk that lives in the shallow waters of southern New England. It has a small size and grows in only one location, but don’t let that fool you—this little mollusk packs a punch. The littleneck clam spends most of its life filter-feeding microscopic phytoplankton from the water. To find food, this mollusk tends to be more of an opportunist, hiding out under rocks or in caves until it senses prey nearby. If it does happen to come across something tasty like algae or zooplankton, that’s even better! 

The littleneck clam will use every part of what it finds and store it away for later consumption.

How Did the Littleneck Clam Get Its Name?

Amazingly, it wasn’t until the mid-19th century that people started to call the clam the littleneck in reference to its shell. Back in the early 1600s, the American Indians of the area had a name for the clam—the “mash-a-muck.” The mash-a-muck name was likely given in reference to the clam’s small size and the fact that it could be eaten raw. Another theory is the name littleneck comes from the fact that the clam grows in the shallow waters of the New England coast and has a maximum length (the thickness) of only a little over an inch. However, this is not completely true, as many clams can grow to be much smaller than this.

What Do Littleneck Clams Eat?

Littleneck clams filter the water for algae, plankton, and other small organisms like microscopic diatoms and protists. These organisms are then broken down and absorbed by the clam’s gills. Since the littleneck clam is so small, it can only filter a small amount of water at a time. To get the nutrients that it needs, the clam uses its abalone-like teeth to scrape and shred algae and plankton. This process is called phagocytosis, and it is similar to the way that white blood cells eat bacteria and parasites inside them. The deep sea algae eater: the littleneck clam’s primary diet is algae, but what about the algae that grows in the deep sea? Unfortunately, scientists have never seen it growing, but it seems possible! To find out, researchers lowered a filter-feeding clam off the coast of Australia and found that it was able to feed on the algae at a very high rate. Additionally, the clam had the unique ability to absorb the nutrients from the algae so that it would never die. The researchers named the clam after it was discovered that it is a “deep sea algae eater,” and its name is Meriwillemia.

The Deep Sea Algae Eater

Although the littleneck clam is mostly found on the New England coast, it can be found in other coastal areas as well. In fact, it is so uncommon that it was thought to be extinct at one point. Thankfully, it was rediscovered in the 1980s, and now it is protected. If it were to disappear again, it is unlikely that it would show up anywhere else in the world. One reason why the littleneck clam is so special is that it has a truly unique diet. Most filter-feeding clams eat one type of algae, but the littleneck clam has one that feeds on living organisms from the deep sea. What’s even more amazing is that this deep-sea algae eater has never been seen growing. The only way to find it is to drop a filter-feeding clam into the deep sea and see if it can feed on the deep sea algae.

A Filter for Everything Else

If the deep sea algae eater is so special and rare, what do you eat in between algae blooms? The littleneck clam was found to have a wide variety of foods in its stomachs, including small crustaceans, plankton, detritus, and even bits of mussels. While the deep sea algae eater has never been seen, scientists believe that it too would be rare and very new to science. To find it, drop a filter-feeding clam into the deep sea and see if it can feed on the deep sea organisms. All of the organisms that the littleneck clam eats are very small, so it wouldn’t be able to eat very much of anything. To find out if the littleneck clam can eat large organisms like mussels and crustaceans, drop it into the deep sea and see what happens.

Not Just for Filtering

Of course, the littleneck clam is best known for its filter-feeding abilities, but it has another skill to add to its repertoire: symbiosis—a relationship with another organism in which both organisms benefit. Some littleneck clams choose to live with sea cucumber or holothurian. Sea cucumbers are filter-feeding animals that can grow up to 16 feet long and live in the ocean depths. What makes the littleneck clam special is that it also chooses to live with them! How does this work? Sea cucumbers eat the detritus and other organic particles that fall to the sea floor. What the clam does is lie on the seabed and cough up the “sea cucumber snacks” for the clam to eat. The clam doesn’t have to go very far from where it was born, making it a great choice for a filter-feeding organism to live with.

The Weird and Wonderful Food Storage Processes of a Littleneck Clam

The littleneck clam’s filter-feeding is unique and very interesting. Most organisms feed by opening their mouths and gulping down food. But the littleneck clam has a unique way to feed—it has to scrape the food off of rocks! When the clam senses a piece of algae or plankton, it has to scurry to rock and use its teeth to shred the algae off of the rock. It then has to drag the algae over to another rock, where it can feed again. This back-and-forth movement is called rasping, and it creates small grooves in the rocks. These grooves create “littleneck tracks” on rocks all around New England coastal areas. One of the tracks is even named after the clam. The “Sea Scraper” track is a small, sharp rock that the littleneck clam uses to scrape algae off of rocks. It was named after a man named Silas Deane who was the first person to take an underwater photo of the littleneck clam.

The Bivalves Are Gentle on the Environment Too!

The littleneck clam has a reputation for filtering the waters of southern New England, but it is also a gentle organism that can help keep the environment clean. When the clam scrapes algae off of rocks, it creates small grooves in the rocks. Over time, the grooves wear down and disappear, but the littleneck clam is so small that it can jump and swim away very quickly. The gentle nature of the littleneck clam means that the grooves are not created very often. If left to its own devices, the littleneck clam could cause some damage to the environment. However, the gentle nature of its filtering allows it to easily shrug off damage to the environment. If the littleneck clam were to die in the wild, it would be gentle on the environment and help keep waterways clean.

Conclusion

The littleneck clam is a great example of how two species can coexist in a single ecosystem. It is a filter-feeding organism that uses physical rasping to remove algae from rocks, and it is also very gentle and clean. The littleneck clam is unique and special, and it should be protected.

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