#clamfacts — Public Fediverse posts

A new study found that when they sense parasitic flatworms in their vicinity, mussels stop filtering to avoid infection. Even more interestingly, they also stop filtering when they detect periwinkles that are an intermediate host for the flatworm. "Oh God, those filthy periwinkles are back, everyone clam up!" #clamFacts

https://www.eurekalert.org/news-releases/1140674

@RussellsBarbershopQuartet a shell is a biomineral with an organic protein matrix! So it is a rock, an organ and a work of art all in one! #clamFacts

@llewelly scallops have some of the most centralized nervous systems of bivalves. They aggregate to mate at certain times of year. They can watch a screen of plankton go by and show signs of increased feeding activity, like us salivating at the Food Channel. They are mesmerized by certain wavelengths of light. They recognize different predators and respond differently to each. They have a lot going on in those nervous systems! #clamFacts

When you hold a shell to your ear, your ear hears the resonation of thousands of environmental noises. But your brain hears the sea. Our ocean is the resonator of our planet. Your brain is right. #clamFacts https://en.wikipedia.org/wiki/Seashell_resonance?wprov=sfla1

@FaithfullJohn re-replying so it can be seen publicly...
according to Williams 2016, "The red fluorescence is a useful character to identify porphyrins, as red fluorescence of non-porphyrin molluscan pigments is rare." I think all that you pictured can be found shallowly/intertidally where UV is more present, (Gibbula more frequently than the others I think, though I'd have to review), so could experience UV in life. Comfort 1948 observed the same thing you have, John, that the fluorescence is only seen in the top whorl for Gibbula. Perhaps it relates to a porphyrin the snail only expresses early in life. Williams observes "porphyrins are
often associated with red, brown or purple shell colouration". It does seem to overlap with the brown color they have at the protoconch in your pic, so I wonder if in this case it is a coincidental property of the porphyrin pigment they use for shell coloration as juveniles. Either way, seems like a lot of research to be done on the evolutionary purposes of shell fluorescence, if any! #clamFacts

https://www.nature.com/articles/162851b0

https://onlinelibrary.wiley.com/doi/abs/10.1111/brv.12268

The Po River Delta in Italy was a huge Manila clam fishery in the 20th century. The clams are native to Asia as their name suggests, but they thrived in huge numbers in coastal lagoons of the Po estuary. They became a huge part of Italian cuisine. Recently, clam harvests have declined 70% due to the introduction of Atlantic blue crabs, which have taken well to the Adriatic and exploded in population, merrily eating the clams by peeling their shells open. One invasion after another, but so far blue crab has not been adopted as a staple in Italian cooking, partially because of their horror at the loss of the clams. I get it! #clamFacts https://www.ctvnews.ca/climate-and-environment/article/an-american-blue-crab-took-over-italian-lagoons-now-fishers-are-looking-for-new-careers/

Giant clams love light. As a general rule, the more light they can get for their symbiotic algae, the better. Some species will even continue to photosynthesize in air for hours exposed by the tide, since their photosynthesis provides them some oxygen. Which makes the "devil clam" (Tridacna mbalavuana) from Tonga and Fiji so weird. It lives up to 100 ft down! The super clear waters where it's found allow it to live as a kind of counterpart to mesophotic corals, which are able to photosynthesize even far from the sunlit surface. Since they are so rare, the devil clams are not well studied, but researchers determined it is able to compensate for its very deep lifestyle through some of the greatest photosynthetic efficiency known from giant clams! #clamFacts https://www.inaturalist.org/taxa/479982-Tridacna-mbalavuana

Clams can integrate all sorts of toxins from the phytoplankton they eat. Some prominent marine ones include paralytic shellfish poisoning, amnesic shellfish poisoning, and diarrhetic shellfish poisoning. There are dozens of known toxins around the world. In freshwater they can accumulate microcystin, which damages the liver. Before collecting clams for eating, always check for warnings from the local water quality or public health agency! #clamFacts

@Virginicus great question! Yes, freshwater mussels draw down both nitrogen and phosphorus through their filtering and carbon burial activities. This is both through direct assimilation of phosphorus in their tissue and buried feces, as well as by encouraging denitrification in the sediment, which turns nitrate back into N2 gas! #clamFacts

RE: https://eupolicy.social/@GreenpeaceEU/116923909086714251

Psst...clams already provide us with tens of billions of free nitrogen removal services a year, and that's just a fraction of their power. If we helped them more through active aquaculture, we could cut nitrogen pollution from farming by about half! #clamFacts

The Japanese littleneck or Manila clam (Ruditapes phippinarum) is a widely eaten and well traveled clam native to Asia that has spread to Western N. America and Europe via the aquaculture industry. A recent study confirmed from iNaturalist observations that it is now on the American East coast, giving it a global home run of invasions. In SF Bay these are quite common in the muddy intertidal. They burrow shallowly under the sand but are otherwise completely unpicky about where they live, which is part of why they're so happy to be transported to new places by us! #clamFacts

Once zebra or quagga mussels get into a water body, it is very difficult to remove them. Many common molluscicides like copper or chlorine are also very harmful to other life forms. Pseudomonas fluorescens strain CL145A is a bacterium that produces a toxin highly specific to zebra and quagga mussels. It can be released as dead cells near the mussels, which ingest it, with the toxin destroying their digestive system. In this way it is similar to Bacillus thuringiensis israelensis (Bti), which is valued for its very specific toxicity to certain insect pests. CL145A is specific enough that it has been used to kill zebra mussels smothering native freshwater mussels, leaving the native mussel unharmed! It is sold as a product called Zequanox, which hasn't been a huge hit due to its comparative expense compared to other solutions. It also can reduce dissolved oxygen in the water when applied indiscriminately. Scientists are trying to find similar targeted solutions that will kill invasive golden mussels, currently spreading through aqueducts and reservoirs in California. #clamFacts

https://www.bizjournals.com/sacramento/news/2025/05/01/marrone-golden-mussels.html?rel=plus

@davidho This needs a hashtag, one that you should follow.

#Clamfacts

Bivalve hinges have to be very resilient, considering the animal's very existence depends on keeping the valves attached and articulated. One team of researchers mechanically opened and closed a freshwater mussel shell 1.5 million times, finding no signs of cracking or deformation from the strain! They found that the mussel uses a fan-shaped structure between the valves to deflect stresses. In the crystal of the shell, a complex fabric of mineral fibers are wrapped in organic materials that act kind of like the reinforcing rebar of concrete, to allow the structure to deform rather than fracture. Engineers could use this as inspiration for more resilient hinge designs! #clamFacts https://en.ustc.edu.cn/info/1150/5111.htm

In 1764, John Adams wrote to his wife Abigail that when he was sick with smallpox, he ate 30 oysters to try to get better. I can't find any evidence that oysters have special therapeutic value against smallpox, though they are rich in zinc, which is an essential mineral for the immune system! #clamFacts

https://www.masshist.org/digitaladams/archive/doc?id=L17640504ja

Georges Bank is a broad elevated area separating the Gulf of Maine from the Atlantic. It has long been a desirable fishing location, and it is ideal habitat for scallops, with its sandy bottom and elevated position in the path of currents delivering phytoplankton food. But in recent years, the northern edge has been closed to scallop fishing. Scallop populations have been plateauing or falling across the Bank, and underwater surveys have determined that the northern edge of the Bank is an important site that scallops swim to and aggregate for mating, helping seed populations of scallops across the broader bank as a whole. Unfortunately after lobbying by fishermen, the Trump administration has now decided to throw that science out the window and ordered that area be opened for scallop harvesting, prioritizing short term profits over preserving an important New England seafood resource for future generations. #clamFacts https://www.reuters.com/world/us/us-lowers-regulatory-burdens-fishing-adviser-navarro-says-2026-07-02/

Olympia oysters (Ostrea lurida) are our native oyster in estuaries on the West coast of North America. They are marvels of evolution, able to survive extreme swings in salinity and turbidity often seen in their native environment. As another adaptation to their extreme habitat, they brood their young within their shell for a couple weeks to a month, to increase their chances of survival. Some years, they may be nearly wiped out by extreme high flow events, and they maximize their chances of finding a mate during the following interval by alternating sexes annually (sequential hermaphroditism). There were once billions of these oysters in SF Bay in huge reefs, where they were harvested sustainably for thousands of years by native peoples, who produced enormous shell mounds as ceremonial monuments to their relationship with the Bay. But in the era of colonization they were almost wiped out by overharvesting, introduced predators/diseases, pollution and habitat destruction. These days the vast majority of farmed oysters are Japanese oysters, which grow faster and reach much bigger size. Nevertheless, Olympia oysters persist and can be found all throughout the Bay in somewhat sparse concentrations, biding their time for when conditions are more to their favor. I have full faith they will inherit the Bay after we're gone! #clamFacts

Giant clams produce ~8 kg/cm2 of closure pressure (114 psi), less than a human bite. So you'd feel a big pinch if one closed on you, but not dangerous! They generally don't want you in their shells with them, so they'll reopen if you keep still, and large clams often can't close completely. However, since their shells are so heavy, their adductor muscles must be very resilient, sustaining >500 kg of tension for mature individuals! #clamFacts

@bug_gwen The best example I could find of a land clam is "The saddle oyster, Enigmonia aenigmatica, is a marine species that could be considered amphibious. It lives above the high tide mark in the tropical Indo-Pacific on the underside of mangrove leaves, on mangrove branches, and on sea walls in the splash zone." (from Wikipedia)

So I think the shrimps win this round.

#clamFacts

Contrary to their name, American oystercatchers don't *just* eat oysters. In one study, around 2/3 of their diet was actually sand crabs. But they do eat a lot of bivalves, using their chisel-like, fast-growing bills to smash or pry open oysters, mussels and other intertidal bivalves! Murder! 🫣 #clamFacts

Oysters are often farmed in floating cages or bags. This way they are protected from many predators, and floating near the surface they are always among the the tasty phytoplankton that are their preferred food, rather than having to wait for the plankton to sink to the bottom! #clamFacts

@soaproot yes giant clams are interestingly "easiest" (still not a beginner pet) as they can get most of their nutrition from light. But most filter-feeding clam species will need supplemental cultured plankton to be added, which most home aquarists aren't prepared to do! #clamFacts

@kboyd I couldn't find a study trying that, but it is a major focus of research from the perspective of light pollution and reducing artificial light at night. But in a similar approach, they have found in multiple experiments that when they play audio of oyster reefs they can induce larvae to settle! #clamFacts https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0079337

Larval oysters have an eye which can detect wavelength and intensity of light. They use the ratio of red and blue light to determine the correct depth at which to settle and attach to the bottom, working from the principle that red light doesn't penetrate as far into the water as blue light! They are phototaxic, attracted to depths where red light is present, and swim up and away from places where only blue light is present #clamFacts

In the Philippines, shipworms (bivalves that eat wood) are called tamilok and are often eaten raw, marinated in citrus in a ceviche-like dish called kinilaw. They also can be deep fried. The taste has been compared to oysters! Since they can be grown with such limited resources, basically just requiring wood, researchers are trying to develop it as a sustainable seafood! I would consider trying it fried but I think I'll leave kinilaw for the more developed palates 😅 #clamFacts

If a bivalve shell has a big honkin snoot off to one side, it is called 'rostrate'. Such structures are often a sign of a big siphon. In the most extreme cases, such as for Cuspidaria, it can a sign of carnivory, with them using a long vacuum hose-like siphon to suck up prey! All the better to eat copepods with! #clamFacts

@Alejandro_P He had been quietly posting about #plankton all this time, waiting for the world to discover it. Speaking of plankton, did you know that plankton, along with algae, detritus, and bacteria, form the diet of clams? #clamFacts @DrPlanktonguy @dantheclamman