#bivalves — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #bivalves, aggregated by home.social.
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Osipova & Lin also evaluate variation in #paleobiodiversity between depositional #environments of the Szekou Formation. Species #richness and #density do not differ significantly between restricted and open #lagoon settings, contrasting with patterns reported for benthic #bivalves
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Osipova & Lin also evaluate variation in #paleobiodiversity between depositional #environments of the Szekou Formation. Species #richness and #density do not differ significantly between restricted and open #lagoon settings, contrasting with patterns reported for benthic #bivalves
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Osipova & Lin also evaluate variation in #paleobiodiversity between depositional #environments of the Szekou Formation. Species #richness and #density do not differ significantly between restricted and open #lagoon settings, contrasting with patterns reported for benthic #bivalves
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Osipova & Lin also evaluate variation in #paleobiodiversity between depositional #environments of the Szekou Formation. Species #richness and #density do not differ significantly between restricted and open #lagoon settings, contrasting with patterns reported for benthic #bivalves
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La décrue des #inondations, les embâcles, les débâcles, font que les tas de saloperies que vous semez sous vos pas, et qui ont été submergées, lavées, entraînées par les flots, arrivent toutes à la mer. Donc dans les parcs à huîtres !
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Cross-barred Venus (Chione elevata)
#Clam #SeaLife #ArtWithOpenSource #CCBYSA #Darktable #MarineLife #Shell #Clams #Bivalvia #Bivalve #Bivalves #Mollusca #Molluscs #Animals #AnimalPhotography #Nature #NaturePhotography #Photo #Photography
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Sawtooth Pen Shell (Atrina serrata)
#Atrina #PenShell #SeaLife #ArtWithOpenSource #CCBYSA #Darktable #MarineLife #Shell #Bivalvia #Bivalve #Bivalves #Mollusca #Molluscs #Animals #AnimalPhotography #Nature #NaturePhotography #Photo #Photography
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Sawtooth Pen Shell (Atrina serrata)
#Atrina #PenShell #SeaLife #ArtWithOpenSource #CCBYSA #Darktable #MarineLife #Shell #Bivalvia #Bivalve #Bivalves #Mollusca #Molluscs #Animals #AnimalPhotography #Nature #NaturePhotography #Photo #Photography
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Sawtooth Pen Shell (Atrina serrata)
#Atrina #PenShell #SeaLife #ArtWithOpenSource #CCBYSA #Darktable #MarineLife #Shell #Bivalvia #Bivalve #Bivalves #Mollusca #Molluscs #Animals #AnimalPhotography #Nature #NaturePhotography #Photo #Photography
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Sawtooth Pen Shell (Atrina serrata)
#Atrina #PenShell #SeaLife #ArtWithOpenSource #CCBYSA #Darktable #MarineLife #Shell #Bivalvia #Bivalve #Bivalves #Mollusca #Molluscs #Animals #AnimalPhotography #Nature #NaturePhotography #Photo #Photography
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Sawtooth Pen Shell (Atrina serrata)
#Atrina #PenShell #SeaLife #ArtWithOpenSource #CCBYSA #Darktable #MarineLife #Shell #Bivalvia #Bivalve #Bivalves #Mollusca #Molluscs #Animals #AnimalPhotography #Nature #NaturePhotography #Photo #Photography
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Atlantic Calico Scallops (Argopecten gibbus)
#Scallops #SeaLife #ArtWithOpenSource #CCBYSA #Darktable #MarineLife #Bivalvia #Bivalves #Mollusca #Molluscs #Animals #AnimalPhotography #Nature #NaturePhotography #Photo #Photography
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Broad-ribbed Cardita (Cardites floridanus)
#Clam #SeaLife #ArtWithOpenSource #CCBYSA #Darktable #MarineLife #Shell #Clams #Bivalvia #Bivalve #Bivalves #Mollusca #Molluscs #Animals #AnimalPhotography #Nature #NaturePhotography #Photo #Photography
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Atlantic Kitten's Paw (Plicatula gibbosa)
#SeaLife #ArtWithOpenSource #CCBYSA #Darktable #MarineLife #Shell #Clam #Clams #Bivalvia #Bivalve #Bivalves #Mollusca #Molluscs #Animals #AnimalPhotography #Nature #NaturePhotography #Photo #Photography
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Turkey Wing Ark Clam (Arca zebra)
#ArkClam #SeaLife #ArtWithOpenSource #CCBYSA #Darktable #MarineLife #Shell #Clam #Clams #Bivalvia #Bivalve #Bivalves #Mollusca #Molluscs #Animals #AnimalPhotography #Nature #NaturePhotography #Photo #Photography
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Ponderous Ark (Noetia ponderosa)
#Clam #SeaLife #ArtWithOpenSource #CCBYSA #Darktable #MarineLife #Shell #Clams #Bivalvia #Bivalve #Bivalves #Mollusca #Molluscs #Animals #AnimalPhotography #Nature #NaturePhotography #Photo #Photography
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La #palourde jaune a dorénavant sa fiche en ligne :
LE GRANCHÉ Philippe, MÜLLER Yves in : #DORIS, 06/12/2025 :
Polititapes aureus (Gmelin, 1791), https://doris.ffessm.fr/ref/specie/5340#mollusques #biodiversite #coquillages #bivalves #MerDuNord #Manche #Atlantique #Méditerranée #Lamellibranchia #biodiversity #FFESSM
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Concurring with The Onion: There Absolutely Nothing We Can Learn from Clams
Screencap of Onion where some sort of scientist is announcing something in front of a Powerpoint slide of a clamLast week, The Onion, a very serious journalistic publication, published a piece “Biologists Announce There Absolutely Nothing We Can Learn From Clams“. As a print subscriber I want to say I played a small part in this article, which I’ve actually hung on my office wall. But I want to take it a step further and write a line-by-line concurrence with everything they wrote!
WOODS HOLE, MA—Saying they saw no conceivable reason to bother with the bivalve mollusks, biologists at the Woods Hole Oceanographic Institution announced Thursday that there was absolutely nothing to be learned from clams.
Wow, I do know a researcher who studies clams at Woods Hole and actually love her work! Nina Whitney is now a prof at Western Washington University but until recently was a postdoc studying how shells can serve as records of climate! I wonder who The Onion interviewed.
“Our studies have found that while some of their shells look pretty cool, clams really don’t have anything to teach us,” said the organization’s chief scientist, Francis Dawkins, clarifying that it wasn’t simply the case that researchers had already learned everything they could from clams, but rather that there had never been anything to learn from them and never would be.
Oh I don’t know a Francis Dawkins, but I’m sure they know their clams! It is true that their shells can look pretty cool. Bivalves include everything from Hysteroconcha dione, with its beautiful color and spines, to Tridacna gigas, which grows to 4.5 feet and weighs hundreds of pounds! And like an Onion, shells have growth layers, sometimes a new one every day, which someone could use to try to figure out how clams record what they eat and how the environment changes. But why would anyone do that?
Close-up view of a Hysteroconcha bivalve shell, showcasing its intricate ridges and coloration, and rows of long spines near the margin. SourceFor me, I guess I haven’t learned anything from clams. I think I already knew in my heart that clams can live for >500 years. I already knew that mussels can filter several liters of water an hour, meaning that a colony of them can filter hundreds of thousands of liters an hour. All this stuff is obvious, actually. Common sense.
“We certainly can’t teach them anything. It’s not like you can train them to run through a maze the way you would with mice. We’ve tried, and they pretty much just lie there.
It is ludicrous that clams could be taught anything or have anything approaching memory or thinking. It is only coincidence that scallops appear to clap their valves to swim, using their hundreds of eyes to navigate to a new location away from predators or toward food. It’s coincidence that they increase their feeding activity when shown a video of food particles. Some researchers have even claimed that giant clams can tell the difference between different shapes of objects! It is so dumb!
From what I’ve observed, they have a lot more in common with rocks than they do with us. They’re technically alive, I guess, if you want to call that living.
Also literally true! Their shell is a biomineral, in essence a living rock, made of calcium carbonate. They are alive in the sense they have a heart that beats, pushing hemolymph around their body. Their heart rate can increase or decrease with different stressors. Remember though, we always knew this. We didn’t learn it through something like science.
They open and close sometimes, but, I mean, so does a wallet. If you’ve used a wallet, you know more or less all there is to know about clams. Pretty boring.”
I myself have wasted time studying this. I attached sensors to giant clams to monitor their feeding activity. If I had learned anything, it might have been that they change their behavior between day and night, basking in the sun to help their photosynthetic algae in the day, and partially closing at night, with those behaviors changing based on how much chlorophyll is in the water. But remember! I didn’t learn it.
The finding follows a study conducted by marine biologists last summer that concluded clams don’t have much flavor, either, tasting pretty much the same as everything else on a fried seafood platter.
I can’t see how anyone would like to eat a bivalve. Especially not a fresh-caught scallop sauteed in butter or a plate of fried clams in New England. Never try that. Leave it to me!
#Biology #bivalves #clams #humor #invertebrates #marineBiology #oceans #satire #science #TheOnion
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We're hiring!
#Bioinformatics #Postdoc on #marine transmissible cancers:
YOU NEED passion about #cancer #evolution, #microbiome &marine #bivalves, a #PhD in a relevant field, a solid computational background, and be able to analyse #multiomics data sets.
WE OFFER a 2-yr Postdoc in an international & vibrant #research environment, state-of-the-art facilities & opportunities for professional development.
https://career.mpi-bremen.de/jobposting/a5697cec59a833bded496aa2af72837c6877acc60
#marineresearch #sciencejobs #researchjobs #WomeninSTEM #joboffer
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We're hiring!
#PhD-position on #marine transmissible cancers:
Passionate about research?
Interested in cancer evolution and evolutionary biology?
MSc background in Biology or Computer Science?Apply! Your work will combine fieldwork, #molecular techniques, #histology and #sequencing data analyses of transmissible #cancers in #bivalves. We offer a 3-year full-time contract located in #Bremen, Germany.
https://career.mpi-bremen.de/jobposting/fd71854ae887707f586dfa0d24e9a18a6d2225e60
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We're hiring!
#PhD-position on #marine transmissible cancers:
Passionate about research?
Interested in cancer evolution and evolutionary biology?
MSc background in Biology or Computer Science?Apply! Your work will combine fieldwork, #molecular techniques, #histology and #sequencing data analyses of transmissible #cancers in #bivalves. We offer a 3-year full-time contract located in #Bremen, Germany.
https://career.mpi-bremen.de/jobposting/fd71854ae887707f586dfa0d24e9a18a6d2225e60
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We're hiring!
#PhD-position on #marine transmissible cancers:
Passionate about research?
Interested in cancer evolution and evolutionary biology?
MSc background in Biology or Computer Science?Apply! Your work will combine fieldwork, #molecular techniques, #histology and #sequencing data analyses of transmissible #cancers in #bivalves. We offer a 3-year full-time contract located in #Bremen, Germany.
https://career.mpi-bremen.de/jobposting/fd71854ae887707f586dfa0d24e9a18a6d2225e60
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We're hiring!
#PhD-position on #marine transmissible cancers:
Passionate about research?
Interested in cancer evolution and evolutionary biology?
MSc background in Biology or Computer Science?Apply! Your work will combine fieldwork, #molecular techniques, #histology and #sequencing data analyses of transmissible #cancers in #bivalves. We offer a 3-year full-time contract located in #Bremen, Germany.
https://career.mpi-bremen.de/jobposting/fd71854ae887707f586dfa0d24e9a18a6d2225e60
-
We're hiring!
#PhD-position on #marine transmissible cancers:
Passionate about research?
Interested in cancer evolution and evolutionary biology?
MSc background in Biology or Computer Science?Apply! Your work will combine fieldwork, #molecular techniques, #histology and #sequencing data analyses of transmissible #cancers in #bivalves. We offer a 3-year full-time contract located in #Bremen, Germany.
https://career.mpi-bremen.de/jobposting/fd71854ae887707f586dfa0d24e9a18a6d2225e60
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"Here, using bivalve-derived environmental reconstructions, we show that the subpolar North Atlantic has experienced two destabilization episodes over the past ~150 years. The first preceded the rapid circulation changes associated with the 1920s North Atlantic regime shift, suggesting that a tipping point may have been crossed in the early 20th century. The second and stronger destabilization began around 1950 and continues to the present, supporting evidence of recent stability loss and suggesting that the region is moving toward a tipping point."
#bivalves
#ClimateChange
#ProxyRecordshttps://www.science.org/doi/full/10.1126/sciadv.adw3468?af=R
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Hooray, we are growing! 🎉👩🔬
We are happy & grateful to welcome #MinervaFastTrack Fellow Alicia L. Bruzos to study how #cancer spreads & forms #metastases in #marine #bivalves.🦪
mpi-bremen.de/en/Page6547....
@maxplanckgesellschaft
#MaxPlanck #PostDoc #WomeninSTEM #marinescience #Bremen -
La #palourde croisée d’Europe est de retour sur DORIS après une grosse révision.
CONTI Cédric, MÜLLER Yves, LAMARE Véronique in : #DORIS, 12/09/2025
Ruditapes decussatus (Linnaeus, 1758), https://doris.ffessm.fr/ref/specie/1379#Mollusque #bivalves #biodiversite #Atlantique #Méditerranée #merRouge #biodiversity #Lamellibranchia #RedSea #Venerida
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Fighting a clamdemic: A golden mussel FAQ
Source: CDWR on Facebook. I thought about titling this post “Violence of the Clams” until I realized American Dad beat me to it, releasing an episode with that title in 2024I legitimately admire clams. I whole-gilledly believe that they do a lot of good for the world; way more than we do! But there’s no doubt that some types of clams are up to no good, thanks to our help. One of those species is Limnoperna fortunei, the golden mussel. In late 2024, this species was observed for the first time on the North American continent, found attached to various human infrastructure in the Sacramento Delta of California. Since then, it has made it all the way down the California aqueduct all the way to the Southern tip of the Central Valley. Golden mussels are a notorious invasive species, and California officials immediately recognized the potential for disaster here, leading to dramatic policies of containment throughout the state that have tremendously impacted the lives of various people trying to enjoy life on the water.
Map from CDFW showing the locations golden mussels have been observed as of July 2025Since we are in uncharted waters with these mussels, there are a lot of questions about these innocuous-looking but trouble-making clams. In this blog, I will try to answer some of the most frequent questions I’ve seen over the last few weeks. I will caveat this by saying that I currently have no active research on this species, but I am a card-carrying clam scientist, and have a lot of interest in its biology and the significance its presence it will have for our state. So let’s get into it!
What are golden mussels? Where are they originally from? How did they get here?
A clump of golden mussels observed in Brazil by iNaturalist user danialdiasGolden mussels are small mussels, only reaching a bit over an inch in length, native to the Pearl River basin in China (the area around Hong Kong and Macau), but have been spread around the world over recent decades with the help of humans, hitching a ride between continents in the ballast water of our ships. Once settled in a new place, they easily move between lakes attaching to boats being driven around, since they can live up to ten days out of water (talk about holding their breath!). The mussels first spread throughout Southeast Asia, then to Japan, then South America, and now for the first time, to the North American continent. While they are true mussels, in the same family (Mytilidae) as the more famous saltwater mussels you might have seen in tide pools, they can’t tolerate fully marine conditions.
Why are they a problem?
- A now-infamous photo of the mussels coating the inside of a pipe at the Governor Jose Richa Power Plant in Brazil
- They love to attach to heat exhangers, which can cause dams and pump stations to break down. Both are crucial to the California Aqueduct. Photo by Gustavo Darrigan
- They can attach to native mollusks, smothering them. Photo by Gustavo Darrigan
Golden mussels are prolific breeders and make a living by anchoring themselves to any available hard surface using byssal threads. This is relatively uncommon among freshwater bivalves, most of which live on the bottom and don’t attach to surfaces. Golden mussels reproduce by releasing thousands of tiny larvae which spread through the area on river currents. In areas where they attach (such as dams, aqueducts, boats and other infrastructure), they form dense colonies that gum up the works, clogging pipes and and coating surfaces with thousands of their sharp little shells. They can even attach to the roots of native plants and shells of other molluscs and smother them! This causes hundreds of millions of dollars in damages and continuing expense in reservoirs and irrigation systems where they’ve taken hold, like in Japan and South America. If the mussels were to unexpectedly clog the outlet of a Californian reservoir like Lake Berryessa or Folsom Lake, it could be disastrous for people who depend on that water.
Figures from a paper about golden mussels invading Brazil, showing them coating an aquaculture cage, on a buoy, on a power plant hatch, in the entry to a dam turbine, and clogging a cooling pipeQuagga and zebra mussels, originally from Central Asia, are invaders in the Colorado River, the Great Lakes, and reservoirs in Southern California. They have been limited from spreading into most reservoirs in Northern California by the low calcium content of lakes here (a function of our local rocks and geology). But golden mussels have lower calcium requirements than zebras/quaggas, so it is likely that they can reproduce in reservoirs up here. They are also surprisingly resistant to low temperatures, meaning that they could potentially take hold in high-altitude lakes like Lake Tahoe, which could be a disaster for efforts to keep Tahoe blue.
Why are they so successful?
A growing golden mussel colony, with an adult surrounded by younger babies. They only live about 3 years, but what a life they’ll live! Photo by Alexander Karatayev via Great Lakes Echo.Being so prolific in their numbers allows the mussels to transform the chemistry and biology of the waters where they live. Like most bivalves, golden mussels make their living by using their gills to filter particles out of the water column, drawing them down to their mouth to eat. While individual golden mussels are pretty average in their filtering ability, together they work to much more effectively clear the water than other species, thereby depriving those native species of the plankton food they need, and potentially even directly eating the plankton larvae of other animals around them!
Figure showing how densities and size of colonies of toxic cyanobacteria Microcystis increase in the presence of golden mussels. Yum! SourceThe Sacramento Delta has plenty of plankton floating around, so it’s not surprising they’ve decided this is a nice place to live. But while the water-cleaning ability of clams is a useful service they provide, there can definitely be too much of a good thing. The mussels are “ecosystem engineers”, meaning that they make the environment they want to live in. The problem is that what is good living for the mussels is not necessarily the habitat of a thriving Delta. Where they take hold, they exclude native species and generally decrease water quality by trapping dirt and boosting the populations of cyanobacteria. The Sacramento Delta already struggles with toxic cyanobacteria, and don’t need to have the problem be worse! Lower water quality means fewer fish, which is bad for people and the ecosystem.
Why have they shown up now?
https://www.flickr.com/photos/psu-clr/4842157536/
This is actually not the CA Bay/Delta’s first rodeo with foreign clams. Invasions of Asian clams (Corbicula fluminea) and overbite clams (Potamocorbula amurensis) in the 1980s transformed the Bay, with trillions of clams spreading out all the way south towards San Jose and eastward into the Delta after being introduced in Grizzly Bay in the mid-1980s. These clams had enormous impacts on the ecosystem, excluding other bottom-dwelling animals and eating most of the plankton food that other animals rely on. They are thought to have played a major role in the decline of some native fishes like Delta and longfin smelt.
Golden mussels have been making their way around the world over the decades. It is hard for their larvae to survive a couple weeks in the belly of a ship, be released, and successfully take hold, but with enough ships coming to California, it was only a matter of time before all of the stars aligned and a population took hold. We don’t know if the appearance of golden mussels will push out Asian clams, or if they’ll coexist. Asian clams live on the bottom rather than attaching to stuff, but golden mussels may still compete with them for food.
Are there other ways they spread?
Previous studies investigating their spread in South America and Japan determined that virtually all of their spread happens attached to the hulls of ships, in ballast water, or anywhere their larvae can travel downstream. There are rare cases where they are believed to travel upstream in the guts of fish that eat them, being pooped out alive. But those are unusual cases. That also won’t help them spread past dams without a fish ladder. The planktonic larvae have very little ability to swim against the current, so they won’t be able to swim upstream through dam turbines.
A map and timeline of their spread through Japan. Source A map of their appearances and spread through South America. SourceUnlike pea clams, which are famous for attaching to birds by clamping their shells on their feet or feathers and traveling long distances to reach new places, it is not believed that golden mussels can create their thread attachment fast enough to hitch a ride on birds (which is a process that takes hours). So fortunately, I can assure our avian friends that we won’t need to inspect them before they use our reservoirs. At the end of the day, human vessels are the main way these mussels are getting around to far-flung places. In Japan, it took around 15 years to spread river to river through the country, while in South America, it covered most of a large area from Buenos Aires to Southern Brazil in that same period of time, which was proposed to be largely due to greater boat traffic in South American rivers.
Different life stages of larval golden mussels. They’re cute when they’re babies! The bottom right is the “plantigrade” stage when they attach to a boat, at 0.75 mm size. Imagine scanning a boat looking for one of those!Are they good eatin’?
They don’t look exactly appetizing to me. Notice the visible byssal threads! Source: Folsom Lake Recreation AreaThese mussels weigh only a little over an inch at best, with not much meat on them. Unlike Asian clams (Corbicula), which are eaten in some Asian cultures, I can’t find mention of anyone eating golden mussels. There have been attempts using them as a fertilizer calcium supplement, but that needs more research. Additionally, it’s known that the other invasive clams of the Bay/Delta are concentrators of toxins, including selenium from farm runoff, heavy metals, and also toxins from harmful algae. In places where golden mussels colonize, toxic cyanobacteria can proliferate, so they actually make themselves a bit more toxic than other clams in the same place would be!
I don’t think these will be taking over the tapas restaurants any time soon! SourceWhat can we do about them?
We just don’t know how L. fortunei will fare long term in the California Delta and lakes. The previous clam invasions have waxed and waned through time. It’s uncertain whether these mussels will fizzle out, as sometimes happens for invasive species, or are here for the long haul. The speed of their spread throughout the state personally has me suspecting they are here for good. And in the meantime, the invasion has caused huge issues for anglers, boaters and dam operators throughout California this summer, who have had to institute boat inspections at every reservoir in the state. Boats have to be painstakingly checked for mussels stuck to surfaces on the hulls.
Eventually, it is possible that mussels will find their way through, despite these precautions. Some could be missed in the crevices of boats entering various reservoirs. But hopefully that will buy time for dam operators to put forth the needed upgrades and develop procedures to keep them from fouling dams and aqueducts. At that point, the objective becomes mitigation rather than prevention. It won’t be cheap, usually involving manual scraping of mussels off of surfaces, application of hot water, pesticides, and use surfaces that discourage mussel growth.
Map from a 2015 book chapter showing their distribution at that time on top, and predicted places they could invade on the bottom panel. Just as the prophecy foretold! SourceLong-term, our invasive species management needs to move to be more proactive rather than reactive. California was previously recognized to be in the range of territory where golden mussels could appear (see figure above). We can’t allow future invasions to catch us by surprise. To that end, there are laws on the books in California requiring inspection of 25% of incoming ships. So far, we are only inspecting a small part of that number. Additionally, ships were previously required to release ballast water far offshore in the ocean, where freshwater species wouldn’t be able to get a foothold. That policy was also not adequately enforced, and requirements to sterilize ballast water with chemical treatments were ruled too expensive. The state government very recently strengthened the standards, but gave ships until 2030 to comply with a weakened version of the rules, and pushed off compliance with the final strongest version until 2040!
People frustrated about such invasive species in California should insist to their policymakers that we can and must do better. There are many more invasive clam species waiting for their chance at a ride over here to make a living in our waters. It’s not too late to stop the assembly line of species coming to displace the native creatures we all love and value!
#Biology #bivalves #california #clams #Delta #nature #wildlife
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European Thorny Oyster (Spondylus gaederopus)
#Oyster #Shell #CCBYSA #MarineLife #Sealife #ArtWithOpenSource #Darktable #Shells #Bivalvia #Bivalves #Bivalve #Mollusc #Molluscs #Mollusca #Animals #Animal #AnimalPhotography #Nature #NaturePhotography #Photo #Photography
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On continue avec les publications sur les #bivalves de nos côtes européennes et donc aussi françaises (de la Norvège au Maroc, et toute la Méditerranée) : voila la #coque glauque.
MÜLLER Yves, LE GRANCHÉ Philippe in : #DORIS, 03/06/2025 :
Cerastoderma glaucum (Bruguière, 1789), https://doris.ffessm.fr/ref/specie/5770#biodiversite #Mollusca #Cardiida #Atlantique #Méditerranée #biodiversity #lamellibranches #Pelecypoda
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Dans la série des #bénitiers tropicaux déjà commencée, voici une nouvelle fiche à découvrir : le bénitier allongé.
MÜLLER Yves, FAUVELOT Cécile, PENIN Lucie in : #DORIS, 29/04/2025 :
Tridacna elongatissima Bianchoni, 1856, https://doris.ffessm.fr/ref/specie/5863#biodiversite #Mollusca #bivalves #scuba #Lamellibranchia #biodiversity #Cardiida
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Dans la série des #bénitiers tropicaux déjà commencée il y a peu, voici une nouvelle fiche très complète sur une espèce d' #IndoPacifique :
le bénitier de Noé.MÜLLER Yves, FAUVELOT Cécile, PENIN Lucie in : #DORIS, 23/04/2025 :
Tridacna noae (Röding, 1798), https://doris.ffessm.fr/ref/specie/5864#Mollusques #bivalves #biodiversite #Lamellibranchia #biodiversity #Cardiida #Tridacninae #BioSousMarine #FFESSM
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What are pearls?
I often get asked what pearls are and why bivalves make them. Pearls are biogenic gemstones. This means they are valuable rocks made not by inorganic crystallization within the earth, like most gemstones, but instead are produced by life! Interestingly, they are living rocks, composed of true minerals. When I talk about minerals, I mean a solid substance with a known chemical composition and crystal structure.
Pearls are specifically made mostly of a mineral called aragonite. Aragonite is a mineral made of atoms of calcium bound to an ion called carbonate. There are other minerals made from calcium carbonate, like calcite and vaterite. I’ll save those for another blog, and while those are present in small amounts in some pearls, the vast majority of the material is aragonite. The clam uses calcium carbonate to make pearls because it’s a conveniently available material: it’s also what they build their shells from!
Aragonite has a very specific geometric crystal structure at the molecular level, but zooming out slightly, it can be found in a tremendous variety of microfabrics. Like the fabric of our clothes, the shell is essentially “woven” by the bivalve with a certain texture at the cellular level. There are hundreds of types of fabrics, ranging from structures looking kind of like brickwork, to plywood, to actual long fibers of carbonate. But the most valuable pearls are made of a form of aragonite called nacre, which is also called “mother of pearl” for this reason.
The platy microstructure of nacre. See how the tablets are organized into interlocking columns! Source: WikipediaNacre is a very special biomineral for many reasons. To humans, it’s precious because of its beautiful, complex iridescence and luster, which has attracted our eyes for thousands of years. But most clams aren’t making the material for its luster- they value its microfabric. Nacre is made of billions of tiny flattened tablets of aragonite, arranged in tall interlocking stacks. Each aragonite tablet also has little bridges joining it to the neighboring tablet, meaning they don’t easily slide out of place. The plated structure also aids the shell in staying together. Even when fractured, the shell can stay together as plates slide to lock into another shape!
Reviewing the various strengthening aspects of nacre, including the bridges that lock tablets together, the rough surfaces of the tablets that grip against each other, the organics that glue together tablets like mortar, and the tablets sliding into new locking orientations even if they break apart! From Zhao et al., 2018Between the bricks of aragonite are a kind of mortar or scaffolding of protein, binding them all together. This protein scaffolding is extremely important to the overall material. Like the steel rebar in concrete, it strengthens the material, making it less brittle and therefore able to resist forces that might crush the clam’s shell, while still allowing for the material to be very thin. For us humans, those alternating layers of carbonate and protein act like thousands of layers of prisms, refracting the light into thousands of colors depending on the angle it is looked at, meaning that any light becomes a miniature rainbow when it passes through the structure of the nacre.
A snuff box made from a nacreous bivalve shell, at the Vienna Natural History MuseumThis structure makes nacre a “premium” material for clams to build their shells from. It costs much more energy for a clam to make such an orderly microstructure and fill it with so much protein, up to 5% by weight, which is around 10-50 times how much organic material is found in other shell . Nacre is also more vulnerable to dissolving in the water surrounding the clam. For this reason, clams usually will only use nacre in the internal shell layer, isolated from the surrounding waters, using cheaper materials on the outside of the shell, or at least a protective sheath of protein on top (called periostracum). The nacre is present in mussels, oysters and other bivalves vulnerable to crushing pressures of waves as well as crushing predators like fish and birds. Nacre is like the bulletproof vest a clam uses to give itself a bit more powerful armor. Because pearls are made inside the shell, that’s why the most valuable pearls to us are made by oysters with a nacreous inner shell layer. The tropical pearl oysters (genus Pinctada) make some of the most valuable pearls, because it’s particularly rich in organic material and thus has a bright and complex lustre. Pearl oysters have extremely thin shells, which are strengthened by having a nacreous structure. They are
Why do bivalves make pearls? Pearls are essentially part of the bivalve’s immune system. If a piece of sand or debris got under your skin, your body would encase the intrusive object with scar tissue. Bivalves can do better than that, because they use the material of the shell to wrap around the object. Anything can be an intrusive object- a piece of sand, an infection, or even a parasite. For example, pearlfish are parasitic fish specialized to live inside the shells of clams. If they die in the shell, the clam will dutifully set to work encasing the fish in nacre, like Han Solo in carbonite!
A pearl oyster with a pearlfish wrapped in nacre against the inner shell. From the Natural History Museum London collectionMost natural pearls are irregularly shaped, so cultured pearls often use round plastic beads as the nucleus for the oyster to grow nacre around. The farmer wedges the oyster’s shell open, deposits the bead and leaves it for a period of time to allow the bivalve to deposit nacre. At harvest time, the oyster can be shucked to remove the pearl. Some experimental approaches even anaesthetize the oyster to remove the pearl, replace it with a new nucleus and repeat the process, potentially allowing for greater efficiency and humane harvesting, allowing the oyster stock to live for years!
So next time you see a pearl, you can understand that the craftsmanship of these wondrous objects is the result of millions of years of evolution, combined with thousands of years of human ingenuity. Moving forward, researchers are attempting to learn to imitate the structure and methods that clams use to make pearls, which could lead to all sorts of improvements in materials science! Clams again prove their skill in engineering. They have a 500 million year head start against us, but we can always learn!
#aragonite #Biology #biominerals #bivalves #clams #pearls #science #shells
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Sitting & waiting to sign some documents & then can get out of this place, full of unmasked plague spreaders - at least for a few hours until I can bring my client her new air filtration unit.
As I'm waiting, am reading up more on how to make reef balls out of broken seashells. Getting ahead on some research that will help me to help better with several projects along our coasts to restore Indigenous shellfish gardens & utilize the nature engineering powers of bivalves to restore some ocean ecosystems that were destroyed by acts of greed fueled colonialism.
#Decolonization #rewilding #bivalves #MarineEcosystems #VancouverIsland #CoastalBC #Environmental #OceanRestoration
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Black Mussels (Mytilus sp.)
https://commons.wikimedia.org/wiki/File:Black_Mussels_(Mytilus_sp.)_-_Kristiansand,_Norway_2021-08-12.jpg#Mussels #SeaLife #Mytilus #CCBYSA #MarineLife #ArtWithOpenSource #Darktable #Molluscs #Mollusca #Bivalves #Bivalvia #Animal #Animals #AnimalPhotography #Wildlife #WildlifePhotography #Nature #NaturePhotography #Photography
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#Seagrasses filter human #pathogens in marine waters https://phys.org/news/2024-08-seagrasses-filter-human-pathogens-marine.html
#Seagrass ecosystems as green urban infrastructure to mediate human pathogens in #seafood: Phoebe Dawkins et al. https://www.nature.com/articles/s41893-024-01408-5
Coastal urban seagrass ecosystems can significantly reduce human bacterial pathogens, including those with widespread #AntibioticResistance, in marine #bivalves—a vital food source for people around the world.
