#a bivalve

[knuppitalism-with-ue]

I think many people didn't realize it, but the Permian bivalve I posted yesterday and made look like a ship graveyard was indeed over a meter long. Shikamaia was distributed throughout the global north and potentially employed chemosynthetic bacteria.

[qadmonster]

Ko-fi Dooble – “A fusion between a clam and a butterfly“

Skyllop (it’s still completely aquatic)

[critter-creature-or-beast]

By Charles J. Sharp - Own work, from Sharp Photography, CC BY-SA 4.0

[archiesoniconline]

Happy Holidays 2023 from ASO!

Happy Holidays from the ASO Team! This year we're all collectively sharing the seasonal cheer, just like Sonic and pals are! See if you can tell who drew who! And what's that Sonic is holding? Open on Dec. 31st, huh? Guess you'll all need wait just a bit longer for the surprise.

Art by @drawloverlala, @pichi-08, @sofibeth-arts, @lankstir21, @salsacoyote, @corythec, @nebuleeart, @little30flames, @kitareartist, @arantarisu-yamu, @darknoisestudio, Tempo, AluSniper, The Magyar, JonnyUnique, Dict.Cola, Sea-Salt, Gaia Ruggenini, Tom Carter “IndexSonic”, _GR33N_RAT_, Nekasa, JaSketch, Pesky-Pincushion, and AidenEye!

[amnhnyc]

By studying calcifying organisms, Leanne aims to better understand the impacts of human activity on marine ecosystems. Through her research, she hopes to influence policy that helps protect marine calcifiers in the future.

“Why is this important? The idea is that the more porous the shell, the weaker it is. Mussels need strong, robust shells to protect their inner soft organs—and that strong 3D structure is important for ecosystem function as habitat formers and storm defenses.

Currently, the changes seen in shell porosity are not large enough to influence the material properties, so we aren’t seeing weaker shells just yet. But with further warming in our oceans being predicted, this could potentially lead to even more porous shells, potentially impacting mussels’ function as habitat formers and storm defenses, as well as their ability to protect themselves from predation,” Melbourne explains.

Learn more about her research here.

[cuttledreams-bugs]

🪱 #InsertAnInvert2024

Worms: Long and Limbless

Shipworm

Despite the appearance, shipworms are actually a mollusc! These bivalves have evolved to use their shells not for protection, but for boring through driftwood.

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Interested in learning more about the invertebrate animals around us? Join into the year-long InsertAnInvert event organized by Franzanth, where every week a new animal is spotlighted! Draw unique animals, read up on cool facts, or just follow the tag online to see a lot of cool artwork.

Prompt List: https://bsky.app/profile/franzanth.bsky.social/post/3khyob3xn742q

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Like my work? Visit my shop, or support me on Ko-Fi!~

[a-book-of-creatures]

Some representative marine bivalves.

From Storer, Usinger, Stebbins, and Nybakken (1972) General Zoology (5th Ed.).

[bethanythebogwitch]

Wet Beast Wednesday: scallops

I may have only discussed them once before on this series, but I'm not saying "bye" to bivalves. One of the coolest bivalve subgroups are the scallops. While most Bivalves live in one spot their entire lives, scallops boldly go where no clam has gone before and take to the seas, actively swimming.

(Image: a pile of captured scallops. They are bivalves with shells shaped like hand fans with two wing-like structures near the hinge. The shells have ridges running from the hinge to the outer edge. Small pink ID tags have been glued to them. End ID)

Scallops are members of the family Pectinidae. As with all bivalves, they have two shells that interlock with a pair of valves which form hinges. The two shells are not identical. Most scallops prefer to rest on one valve (usually the right one), which results in that shell growing more rounded than the other one. Growing from the back of the shell near the hinge are two structures called wings, ears, or auricles, which are unique to scallops. Another shell feature unique to scallops is the ctenolium, a honeycomb shaped structure that is used to help distrubute byssal threads. Byssal threads are structures found in most bivalves. They are strong and sticky filaments that attach bivalves to rocks. Most scallops only attach themselves to rocks as juveniles and lose the ctenolium as adults. The scallops shell has a distinctive and usually symmetrical shape. Many have distinctive ridges running from hinge to the front of the shell. These are supported by structures called ribs. These provide extra integrity to the shell, but increase weight, requiring an evolutionary balancing act to get the most benefit out of them.

(Image: a live scallop with the opening facing the camera. Inside the shell is a fleshy structure with multiple small tentacles and two rows of small, blue eyes. There is algae and a barnacle growing on the shell. End ID)

The inside of the shell contains the body of the scallop. A large portion of the interior is taken up by the adductor muscle, which attaches to the inside of both shells. The adductor muscle of scallops is larger and more developed than those found in most bivalves. In all bivalve species, its purpose is to close the shells. Scallops also use it for swimming. The scallop adductor muscle is made of both smooth and striated muscle tissue. The striated muscle moves fast but tires out quicker and is sued for rapidly opening and closing the shell when swimming. The smooth muscle is slower but uses much less energy, allowing the scallop to hold its shell closed for a long time. As with all bivalves, the shell defaults to the open position thanks to a structure called the hinge ligament and require active muscle contraction to close. Most of the rest of the body is the digestive system, reproductive system, circulatory system, and nervous system. The nervous system is a fairly simple nerve net and lacks a brain. Unlike most bivalves, scallops do not intake food through a siphon. Instead, they open their shells to let water move over a structure that filters out food particles and imbeds them in mucus. cilia then moves the mucus into the mouth and through the digestive system. The digestive system also passes through the heart. Around the opening of the shell is a structure called the mantle. The mantle is lined with tentacles that help filter out inedible things from the water.

(image: a scallop with one shell removed to show the internal anatomy. End ID)

Also along the mantle are two rows of eyes, one for each shell and up to 200 in total. Most bivalves don't have eyes. Scallops, being swimming animals, do have eyes and they are strange, not just in comparison to vertebrate eyes, but in comparison to the eyes of other mollusks. Each eyeball has a lens, a pupil, two retinas, and at the back, a system of mirrors that direct and focus light in a similar manner as telescopes. The mirrors are composed of guanine (the same stuff as the "G" nucleotide in DNA) and are shaped like convex squares. There can be over 100,000 mirrors in each eye. For a long time, it was thought that the proximity of the mirrors to the retinas would result in an unfocused, blurry image. It has recently beed discovered that the cells that eye can change shape, potentially adjusting the mirrors for a sharper image. Scallops also have more opsins (light-sensing proteins in the retina) than humans and they may not be evenly distributed, potentially allowing different eyes to see different parts of the light spectrum. While it's not clear how much information the scallops can interpret with their lack of a brain, they at least can tell the difference between ares of contrast and can detect motion. Scallops seem to mainly use their vision to detect predators and to adjust their swimming and feeding behavior.

(Image: a close-up shot of scallop eyes. They are blue balls with a black pupil. End ID)

Now for the reason Spongebob turned scallops into the undersea equivalent of birds. Unlike the vast majority of bivalves, who are either immobile or bury themselves in the sediment, scallops are free-swimming. At least most of them, there are some species that live their lives attached to rock or another structure, like mussels or oysters. The body plan of scallop shells is adapted to facilitate swimming. They have two main means of locomotion called swimming and jumping. Both involve the scallop opening the shell to intake water, then rapidly closing it to force the water out. While swimming, the water is ejected through small holes near the hinge called exhalant apertures. The water is forced over the shell's wings and can be sent out over the left or right wing. Most of the time, they will alternate which wing the water is pushed over, resulting in a zig-zag movement. In jumping, the water is forced out the way it came, propelling the scallop backwards. It usually comes to a rest on the sediment between jumps. Both swimming and jumping cost a lot of energy and the scallop will have to rest afterwards. their locomotion is used to avoid predation, with starfish being their main predators. Some species also have a muscular foot that can extend from the shell and is used to bury the scallop.

(Gif: a scallop swimming over a field of seagrass, showing off the zig-zag motion and its ability to alter its course. End ID)

Some species of scallop are dioecious, meaning they have distinct males and females. Others are simultaneous hermaphrodites while still others are protandrous sequential hermaphrodites, beginning their lives as males and becoming females when they get older. Their reproductive organs are called roe and are red in females and white in males. Scallops are broadcast spawners. They release eggs and sperm into the water column. After a few weeks, fertilized eggs will hatch into drifting larvae called spat. Spat look like miniature, transparent versions of the adults. As they age, the spat will drop to the seafloor. This event has the delightful name of spatfall. The spat use byssal threads to attach themselves to whatever they can find and will remain like that until they have matured. Most species lose their byssal threads as adults, but a few retain them and do not become swimmers. Depending on species, scallops can live for up to 20 years.

(Image: a group of spat housed in captivity They are smaller, transluscent versions of the adults. End ID)

The part of scallops that people usually eat is the adductor muscle, though the roe is also edible. Scallops have been eaten by various peoples for millennia and excessive catching has caused severe declines in wild populations. This has led to the rise of many aquaculture methods for growing scallops from the spat stage. Because scallops are filter feeders, they improve local water quality and when their numbers diminish, water quality worsens. On the other hand, when massive numbers of scallops are raised together in aquaculture, they can cause localized eutrophication, an increase of nutrients that triggers massive microbe growth and reduces oxygen levels in the water. Dredging, the main method of capturing wild scallops, destroys benthic ecosystems, which can take decades to be restored. All of this for a food that tastes like congealed air.

(Image: a scallop aquaculture setup. It consists of multiple nets hanging from the surface of the water, each separated into multiple layers holding multiple scallops. A SCUBA diver is swimming through the area. End ID)

[knuppitalism-with-ue]

Results from the #paleostream

Diplocaulus minimus, Shikamaia (giant Permian bivalve), Placerias (male and female) and Acanthodes

[qadmonster]

Ko-fi Dooble:

"Geoduck fakemon or critter"

[bethdehart]

Draconic Bivalve Adopt

Drawn on stream! This design is so fun I hope they go to a good home. You can purchase here on ko-fi!

Check replies or dm for availability!

[franzanth]

Ascaulocardium armatum

Fossil clams that built a case around their body, with bizarre pipe-like protrusions sprouting all over the place like a human heart that grew too many arteries.

Read the paper

[mindblowingscience]

A new study sheds light on the unexplored diversity of galeommatoidean bivalves, a little-known group of marine mollusks, from the western coast of South Africa. The research, led by Paul Valentich-Scott from the Santa Barbara Museum of Natural History, along with collaborators from the University of Cape Town, Sea Change Trust, Stellenbosch University, and the University of Colorado Boulder, offers a curious glimpse into the habitats, symbiotic relationships, and taxonomy of these interesting creatures.

Continue Reading.

[taxonomytournament]

Taxonomy Tournament: Molluscs

Polyplacophora. This class is made up of chitons, marine creatures that live under rocks. Their shells are made up of eight plates, protecting them while also allowing them to flex upwards or curl into a ball.

Pteriomorphia. This subclass is made up of bivalves with large gills used for feeding and rudimentary photoreceptors. Memebrs include mussels, scallops, oysters and pen shells

[existancexisxstillxpain]

Someone left a hot dog on the tv stand for a long time yesterday at the party and I couldn’t not think about it the whole time (they even moved it slightly but didn’t finish it!!!!)

I didn’t even wear this outfit to the party but i still like it

[geopsych]

Fresh water mussels and the rippling of the lake.