Dr. Dan Killam
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dantheclamman.scicomm.xyz.ap.brid.gy
Dr. Dan Killam
@dantheclamman.scicomm.xyz.ap.brid.gy
19 followers 1 following 170 posts
Environmental scientist and eclamgelist

Provider of #ClamFacts

[bridged from https://scicomm.xyz/@dantheclamman on the fediverse by https://fed.brid.gy/ ]
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dantheclamman.scicomm.xyz.ap.brid.gy
On Wednesday @ 12 Pacific time I'll be joining my fave mag Bay Nature for a talk about salinity in SF Bay! 🧂🌊 Register at this link: free for members or $5 for nonmembers ! https://baynature.app.neoncrm.com/nx/portal/neonevents/events?path=%2Fportal%2Fevents%2F27375
Painting of SF Bay and event info for my talk: Join Bay Nature and environmental scientist Dan Killam for a talk on the seasonality of salt in our San Francisco Bay waters and how animals have adjusted their lifestyles to survive in response. As Susan Kuramoto Moffat writes, "nearly a quarter of the Bay sloshes in and out of the Golden Gate twice each day with the tide, mixing salt and fresh water on a staggering scale." Within the Bay, these levels of salinity vary greatly over the year (and even over the course of a single day) with early autumn being the saltiest time of year. This fluctuation poses a challenge for the animals living in the Bay, so tune in to learn how mollusks and others make do. This talk is free for Bay Nature Members and $5 for Nonmembers.
November 10, 2025 at 10:00 PM
dantheclamman.scicomm.xyz.ap.brid.gy
A reef is a sedimentary structure supported by the skeletons of living organisms. Corals are the most famous reef builders, but oysters build them too! Cretaceous rudists, Jurassic lithiotids and bivalves from other time intervals of the past actually rivaled […]

[Original post on scicomm.xyz]
Figure from Kiessling 2009 showing the number of reefs through time. Corals are dominant but often decline following extinctions, and there are points like Cretaceous, early Jurassic and early Triassic when bivalves made up a significant proportion of reefs
October 30, 2025 at 3:27 PM
dantheclamman.scicomm.xyz.ap.brid.gy
@soaproot a lot of them, yes! though periostracum can have a bright golden color just due to coincidental properties of the proteins involved!
a Bathymodiolus mussel. it is an oddly bright, shiny copper color!
October 28, 2025 at 4:08 AM
dantheclamman.scicomm.xyz.ap.brid.gy
Bivalve shells are often colored, either by optically active pigments in the crystal structure of the shell itself, or by the protein layer on top (periostracum) being colored. Yellow and brown are most common, with green and blue being most unusual. As with […]

[Original post on scicomm.xyz]
Beautiful figure from Grant and Williams 2018 showing a spectrum of different shell colors of different bivalves, basically covering all of ROYGBIV. Interiors and exteriors of shells can be colored. Some are only pigmented where the adductor mussel attaches to the interior
October 28, 2025 at 1:50 AM
dantheclamman.scicomm.xyz.ap.brid.gy
Lewis Carroll's The Walrus and the Carpenter accurately portays how much walruses love to eat bivalves. But walruses mostly hunt in deeper waters than where oysters live, pulling their tongue into their mouth like a piston to suck clams out of the shell. One […]

[Original post on scicomm.xyz]
A blunt gaper clam, showing its pale white aragonitic shell, covered with patchy periostracum with a bald spot at the jumbo. A large obscene looking brown siphon emerges from the left of the shell Illustration from Lewis Carroll's Walrus and the Carpenter showing a walrus talking to oysters on the beach
October 20, 2025 at 8:19 PM
dantheclamman.scicomm.xyz.ap.brid.gy
Unlike their gastropod and cephalopod relatives, there are no known pelagic bivalves that remain in the water column throughout their lives! Many bivalves start as planktonic when they are veligers (larvae), but they all eventually settle down. There are fossil […]

[Original post on scicomm.xyz]
Fig. from Gofas 2000 showing P. henseni from Louisiana. The adult is barely 2 mm long, semi-transparent and nondescript. Growth lines are visible on the shell surface, and a prodissoconch (the larval shell) at the umbo Map from Allen and Scheltema 1972 showing observations of Planktomya larvae. Dark dots basically cover the entire N. Atlantic from Africa to Brazil to Gulf of Mexico to Canada!
October 14, 2025 at 8:34 PM
dantheclamman.scicomm.xyz.ap.brid.gy
It is common for aquaculture to triploid oysters as their stock! They have three sets of chromosomes, rather than the usual two, rendering them sterile. This means their body growth is faster, because they don't put energy into reproduction! A triploid oyster is […]

[Original post on scicomm.xyz]
From Wikipedia, a comparison of representative diploid and triploid oysters. The triploid is twice the body length, with probably three times the soft tissue in terms of area
October 6, 2025 at 7:38 PM
dantheclamman.scicomm.xyz.ap.brid.gy
In October 2024: golden mussels were first detected at the Port of Stockton. They likely came in the ballast water of a ship, coming from one of the places they've previously invaded. In the year since detection they have rode the CA aqueduct all the way down to […]

[Original post on scicomm.xyz]
October 4, 2025 at 8:43 PM
dantheclamman.scicomm.xyz.ap.brid.gy
Zachsia zenkewitschi is an extremely cool and strange shipworm that bores into the rhizomes of seagrass on the coasts of Japan and Russia. The females are ~1 cm long and do the burrowing. The males stay larval sized and the female keeps a "harem" of them tucked […]

[Original post on scicomm.xyz]
Diagram from Shipway et al. 2016 showing a Zachsia tucked into a seagrass rhizome like a corndog. She has two siphons poking out the end of the rhizome. Behind those is a kind of cuff or pouch where males spend their lives. The progression of larval to adult males is shown, with the adult looking barely any different from the larvae. Further back is a brood pouch where the mother clam broods her fertilized eggs
September 26, 2025 at 11:19 PM
dantheclamman.scicomm.xyz.ap.brid.gy
In July 1927, over 100 people in San Francisco were sickened from eating mussels. Six died. All experienced loss of feeling and tingling starting as little as a few minutes after their meal, which progressed in some patients into paralysis. There was mass terror […]

[Original post on scicomm.xyz]
A microscope image of Alexandrium catenella. It looks like two brownish hamburgers stuck together
September 25, 2025 at 6:16 AM
dantheclamman.scicomm.xyz.ap.brid.gy
If a clam claps its valves in the sea and no one is around, does it make a sound? Actually, yes. Researchers were able to use a sensitive mic to pick up the sound of scallops "coughing" as they close their valves, expelling water. It could have use as a […]

[Original post on scicomm.xyz]
A schematic from Di Iorio et al 2012 showing a microphone suspended in a tank of scallops, as well as a top down view of the locations of the scallops Figure from the paper showing the waveform of the cough from the scallop, and also a couple spectrograms
September 18, 2025 at 3:21 AM
dantheclamman.scicomm.xyz.ap.brid.gy
Clam gardens have been used by Pacific Northwest native tribes for thousands of years. They build rock walls to trap sediment, at the right height to be immersed at high tide but also exposed for harvest at low tide. This encourages burrowing clams to settle in […]

[Original post on scicomm.xyz]
Overhead picture from the Northwest Indian Fisheries Commission of a clam garden being built. It is a low rock wall below the tide line. An assembly line of workers carry rocks to the right elevation Diagram from Lepofsky et al. 2021 showing a cross-section of a typical clam garden. The edge of the wall ends exactly at the low tide line, trapping sediment behind it which is exposed at those intervals. It builds the beach surface to a shallower slope, with the shallowest dirt behind the wall the habitat of littleneck clams, while butter clams live deeper.
September 12, 2025 at 8:29 PM
dantheclamman.scicomm.xyz.ap.brid.gy
@llewelly @soaproot it's a super interesting question and it would have to be investigated if there were a taphonomic signature of pseudofeces! This a pretty well cited bulletin from 2012 reported it is poorly understood!
Regurgitations of invertebrates are mainly referred to as pseudofeces. Suspension-feeding molluscs gather food by filtering sus- pended particles out of the water with their gills. Mucus binds these particles and then they are transported to the palps beside the mouth where they are sorted for edibleness. Those particles found inedible are further bound in mucus and expelled from the system as pseudofeces. Mucus-binding is essential for efficient ejection and allows these pellets to survive as sand-sized sediment grains for some time. These regurgi- tated mucus-bound pellets resemble feces quite closely, differing only in not having passed through the bivalve's gut (e.g., Prins et al., 1991 and references herein). In the fossil record, they therefore might be misidentified as coprolites. Criteria to distinguish pseudofeces from real fecal pellets seem not to have been studied, yet (Prins et al., 1991).
September 6, 2025 at 3:10 PM
dantheclamman.scicomm.xyz.ap.brid.gy
Nacre (mother of pearl) isn't very stable chemically, so fossils with nacre are less common, because they dissolve during the millions of years exposed to heat, pressure and fluids in the earth's crust. But in the right conditions, we can find pearl fossils […]

[Original post on scicomm.xyz]
view of a large fossil pearl from Pseudostrea congesta, which was attached to the shell of the large clam. it is made of dully transparent brown calcite and is around 4-5 cm across. on the base of the pearl, growth lines can be seen radiating from the center view of a smaller pearl 5 mm across, cut in half to expose the fine growth lines. these are cleanly circular, but with some signs of larger crystals (called "spar"), a classic marker of recrystallization of the original material
September 5, 2025 at 8:14 PM
dantheclamman.scicomm.xyz.ap.brid.gy
Clams of course produce poop from digested material, but they also produce pseudofeces from all the stuff picked up by their gills that they don't eat. The pseudofeces is packaged up in mucus. Both the poop and not-poop are shot out the siphon when the clam claps […]

[Original post on scicomm.xyz]
Fig from Galimany et al 2018 showing an eastern ribbed mussel and comparing its feces and pseudofeces. The pseudofeces is generally more diffuse than the actual poops. A bright green poop is the result of being fed monoculture of green algae Tetraselmis, while the brown poop is a mix of particles from seawater
September 3, 2025 at 5:08 PM
dantheclamman.scicomm.xyz.ap.brid.gy
When clams are buried, they will frantically try to dig to reach the surface. Their digging leaves impressions, creating trace fossils called "Lockeia" which are marks of ancient storm deposits and of clams being buried alive! Spooky! […]

[Original post on scicomm.xyz]
Photo by Mark Wilson, showing a bunch of Lockeia, looking like gingersnap cookies poking out of a reddish Cretaceous sandstone. Some impressions of the clams movement are visible in the surface
September 2, 2025 at 9:49 PM
dantheclamman.scicomm.xyz.ap.brid.gy
Yo dawg we heard you like shells...the Stimpson chimney clam is a shell in a shell. These little bivalves bore into loose shells, building little igloo like chimneys of cemented shelly fragments once they grow past the thickness of their host shell! #clamfacts
A small face of xzibit floats among close ups of the chimney clam shells, very small gray nondescript little valves. A sand dollar is pierced by three chimneys, looking like little tufa towers going through the shell A chimney clam chimney emerges from a golden gastropod shell. It is composed of many small fragments cemented together An ark shell is full of holes like swiss cheese, with the interior showing little igloo like chimneys at the end of the burrows
August 31, 2025 at 11:27 PM
dantheclamman.scicomm.xyz.ap.brid.gy
The file shells are very unusual bivalves. Some can give disco displays using reflective particles in their flesh, believed to confuse predators. They have a lot of overlap with scallops in being able to swim and many species having eyes, leading them to […]

[Original post on scicomm.xyz]
The fragile file clam, Limaria fragilis. It is vividly orange with long tentacles spreading out, each tentacle nearly the length of the clam's body!
August 28, 2025 at 8:02 PM
dantheclamman.scicomm.xyz.ap.brid.gy
Jingle shells are a family of very thin, flat bivalves that live attached to surfaces. The mangrove jingle shell lives attached to the lower leaves of mangroves! It is not actually air living, and still needs to be immersed by the tides occasionally to survive […]

[Original post on scicomm.xyz]
A golden colored, semitransparent mangrove jingle shell adhered to the leaf of a mangrove. It is very thin and limpet like, with visible growth lines
August 26, 2025 at 3:29 PM
dantheclamman.scicomm.xyz.ap.brid.gy
When a whale dies and falls to the seafloor, its lipid-rich bones decay and produce a lot of sulfide. Idas washingtonia is a mussel that specializes in colonizing during this "sulfophilic" stage, years after the initial whale fall. Up to tens of thousands of […]

[Original post on scicomm.xyz]
A small Idas washingtonia clam. It is pale in color and has finely branching gills that would be full of its symbiotic bacteria
August 25, 2025 at 3:22 PM
dantheclamman.scicomm.xyz.ap.brid.gy
There are deep sea Bathymodiolus mussels >1500 m deep that still grow their shells following a tidal schedule, far below depths where tides have influence! Researchers believe deeply conserved genetic traits drive their biological clocks, but much is unknown […]

[Original post on scicomm.xyz]
An aggregation of Bathymodiolus mussels at a hydrothermal vent. They are golden brown in color. A crab climbs over the piles of them
August 18, 2025 at 3:26 PM
dantheclamman.scicomm.xyz.ap.brid.gy
The bivalve's gill cilia do some limited rejection of non-food particles, but are generally dedicated to grabbing anything they can. The main sorting action is provided by labial palps, near the mouth, kind of like lips. These grab food particles to pull near the […]

[Original post on scicomm.xyz]
A dissected bivalve showing different body parts including large feathery gills and also the labial palps alongside, looking like a pair of tweezers A drawing of a bivalve, showing the fine gills and the tweezerlike palps next to the mouth
August 11, 2025 at 8:36 PM
dantheclamman.scicomm.xyz.ap.brid.gy
Bivalve gills, also called ctenidia, are made of many fine filaments, which are covered by countless microscopic cilia. The cilia are triggered to beat when the bivalve smells something nice, causing water to flow past. The cilia stick to tasty particles and pass […]

[Original post on scicomm.xyz]
An electron microscopic view of a mussel gill filament covered by cilia, bifurcated and covered with hairs
August 11, 2025 at 6:01 AM
dantheclamman.scicomm.xyz.ap.brid.gy
Clam chowder of New England and Manhattan varieties traces its origin back to quahog stews made by native peoples of the region. Seafood stews are a *very* old global tradition, and later waves of immigrants brought additions of dairy, potato, and for Manhattan […]

[Original post on scicomm.xyz]
A clam chowder with potato, bacon and dairy base, sprinkled with soup crackers
August 4, 2025 at 4:21 PM
dantheclamman.scicomm.xyz.ap.brid.gy
The largest known verified natural pearl weighs 28 kg/61 lb! It was made by a giant clam, and is owned by a Filipino-Canadian man who inherited it through family. Giant clam pearls are not made of nacre (mother of pearl) like the iridescent gemstone pearls, which […]

[Original post on scicomm.xyz]
A man in a pearlescent jacket standing with a long white pearl, looking like a footlong oval piece of ivory. The pearl is held by a rather gaudy golden octopus sculpture for some reason
July 30, 2025 at 12:13 AM