Sub-Neritic Gentrification

For November we will be doing some deep thinking about deep-sea mollusks in an attempt to understand the complex history and adaptations of these animals living in the depths of our oceans. Biodiversity of today’s marine snails can be traced to several different ecological and environmental phenomena, but in the Deep-Water Helmet Shell Galeodea keyteri, it is likely a case of adaptive radiation exploring new realms. The Helmet Shells (Cassidae) are a speciose group of large, shallow-water tropical and temperate marine snails that range among the intertidal coral rubble and sand flats to offshore muds, but as this evolutionarily successful group of gastropods continued to diversity into different niches, several species moved into deep-water to establish new ways of living. At these depths staying alive presents serious challenges with an extremely cold, low oxygen, nutrient-poor, and high-pressure environment, so some deep-water species trended to smaller, slow-growing physiologies like as a way to successfully conserve energy and resources. Since the dark depths lack sunlight needed for algae to grow, most species of deep-sea mollusks are either scavengers or predators, with little resources for vegetarians to survive. Like all Helmet Shells, Galeodea keyteri is a carnivore, specializing on starfish, brittle stars, and urchins. Catching their slow-moving prey with a muscular foot, glands in the proboscis secrete a fluid rich in acids that dissolve the echinoderm’s calcium-carbonate skeletons, while a radula drills into the weakened parts of the body to extract nutrients from their internal organs. A tough environment requires innovative strategies and hardy adaptations for a species to survive. Ain’t natural selection grand?

Molluscan Methuselah

While some species of deepwater mollusks are derived from shallow-water taxa that extended into and adapted within deep ocean ecosystems, other taxa of marine mollusks are taxonomic geezers with a much longer history. The Slit Snails (Pleuorotomariidae) are perhaps the oldest still-living lineage of marine snails, extending back in the fossil record more than 500 million years. Named because of its long slit at the aperture allowing for extension of their respiratory siphon, they were abundant in the shallow reefs throughout the world. Between the Late Cretaceous (ca. 90 million years ago) and the middle Eocene (ca. 40 million years ago) is when most modern lineages of shallow-water reef-living gastropods originated and diversified, and also the time when slit shells seem to disappear from that same fossil record. Among paleontologists and malacologists, the general hypothesis is that these modern taxa somehow out-competed the slit shells for food, or perhaps were more adapted to changing marine climates or fluctuating sea levels of the time, forcing the slit shells into progressively deeper and deeper water. This type of ecological displacement and bathymetric submergence has been seen in many other deep-sea groups, including corals, crinoids, brachiopods, and fishes. Today, slit shells are found in depths exceeding 3,000 meters, living the hi-life eating sponges in a cold, dark, lonely, nutrient-poor world.

Die-Hardest

As far as the origins of deep-sea gastropods go, we’ve visited two scenarios: new lineages of shallow-water snails radiating into deeper waters, and those formerly shallow-water taxa that have been out-competed in the shallows and forced into deeper, less productive habitats. But there’s a third group of deep-water snails that are so tough, so extreme that they can live in shallow and deep water. Here is the Checkered Hairsnail (Trichotropis cancellaria; Capulidae), the James Bond, the Bruce Willis, and the Rock all coiled up into one extreme snail that ranges from the intertidal zone to depths of nearly 2,000 ft. (600m). Is it true grit or it’s hard-boiled soul that make it impervious to the relentless cold, pressure, and darkness of the deep sea? Their broad range is more likely the result of two things: (1) a wide and variable physiology that can tolerate the extremes of shallow to deep; and (2) its broad diet that it can obtain at any depth. You see, the Checkered Hairsnail is a suspension-feeder, meaning it feeds on the decomposing bits of animal debris suspended in the water, which it traps by sticky mucous, and that kind of detritus is found in all habitats. However, it’s a sneaky critter. When the floating slurry of decomposition becomes scarce, they will parasitize tube worms by inserting their proboscis down the mouth of the worm and pumping out the contents of the worm’s stomach. Evolution: the weirder the better.

Slo-Mo Snail
Shallow-water gastropods live the good life. Warm water, a sunny sea rich in oxygen, and plenty of food provides them the metabolism to live fast, grow big, and die young, relatively speaking, of course. The flipside in the deep sea is a life of constant near-freezing cold, little available food, and water suffocatingly sparse in oxygen. This shell of the Catalina Turrid (Antiplanes catalinae, Pseudomelatomidae) who lives at depths of up to 4800 ft (1460 m), tells its story of life in this harsh realm. Growth lines, which indicate the increase and cessation of shell development, are seen as wide bands often far apart in curving spire of fast-growing shallow-water shells. In this species, the growth lines are close and compact, showing very slow growth and likely a long life. Their low metabolism provides little extra energy for their minimal growth and reproduction, so these snails probably take the developmental route of the tortoise over the hare. This shell tells another and more concerning story. Once only collected during deep-ocean trawls by research vessels, this species was prized by collectors as a rarity and an oddity. With commercial fisheries abandoning over-exploited fishing grounds along the shallower coasts, fishing has gone into the deep ocean to tap into those fragile resources. This specimen was taken as unintentional bycatch by a deep-water shrimp trawler, and though it wasn’t the target of the fisheries, the sparse populations of these slow-growing snails cannot sustain even the modest impact by commercial fisheries

Post-Docs Please Enquire

The curse of working with deep-sea gastropods is how few specimens are in museum collections, and what very little is known about them. That too is the siren’s call of opportunity in deep-sea malacological research. The Japanese Pagoda Shell (Columbarium pagoda, Turridae) has been known to science for close to 200 years, based on relatively few well-documented specimens in museums and private collections scattered throughout the world, yet virtually nothing is known about their ecology. Diet, trophic niche, age, growth rates, reproduction, population structure, predators, parasites, physiology, ecological associations, movements – none of that has been adequately documented. If all mysteries in the ocean were solved, there would be no jobs for future under-paid post-docs or over-worked assistant professors. Those with grant funding, a modicum of workaholism, and access to deep-sea technology could pioneer new directions into a richer ecological understanding of the deep ocean’s marine mollusks. That siren’s call can just as easily dash unfeasible projects on the rocks of financial destitution and lead to deep regret of one’s research program and entrée into a life of constant self-medication and personal validation. These mysteries await the bold, but favor the wise.

The post Malacology Monthly: Going Deep first appeared on Deep Sea News.

1) Cockles got feet, and they know how to use ’em. This isn’t a tongue, or some other fleshy pink appendage, but rather a foot, and a long, distensible, and flexible one at that. When in the sand, this foot extends deep into the sediment, and as it contracts, it pulls the shell down into the sand beyond the eyes of its predators. When you dine on cockles, this is what you eat.

2) Trippy aquatic castanets? Ghost shell from a Japanese horror movie? Nope, this is a scallop doing what scallops do for much of their life – trying to get the heck away from a predator. Unlike cockles that hide beneath the sand, the muscular adductor that snaps the shell shut creates a jet of water that moves them in short, jerky blasts through the water. While their escape plan isn’t all that great, it may just be good enough to get out of the path of slow-moving starfish, their most feared predators.

3) You can almost hear the thumping oonce oonce oonce rave beats where the disco clam lives. It’s not really a clam at all, but a very flamboyant bivalve called the Electric Flame Scallop. Their light show pulsates within the fleshy mantle, making small mesmerizing blasts of light. Unlike most respectable sea creatures, they don’t generate bioluminescence, instead they reflect ambient light through a thin layer of silica microspherules embedded in their flesh, making the light appear as electrical currents in that outer layer of skin. The hot-pink feather boa of tentacles may give them additional glam-rock cred, but they also contain distasteful sulfur compounds, so the blinking lights may give potential predators a fair warning for the subsequent mouthful of regret.

4) Octopus are (literally) cold-blooded killers, and they’ve got a whole toolkit of ways to subdue different kinds of prey. With clams, they grasp the shell with their tentacles, and using a sharp tooth-studded tongue, drill a small hole through the shell and inject a paralytic venom. The drugged clam relaxes its grip and they octopus can easily pry the shell open. With the former tenant now lunch and just a fading memory, the octopus takes over the clam’s home and uses the thick shell for protection from its own predators, keeping one eye open for danger.

5) Squee Alert! Bears and clams rarely meet, but when they do the results can be sickeningly adorable. Grizzly bears along the Pacific Coast often forage for marine invertebrates at low tide, and have even been seen pawing through the sand for clams. This young grizzly is learning the art of clam digging, yet hasn’t perfected the technique, and now has a huge cockle clamped to one of its claws. You’re Welcome!

The post Five Mind-Blowing Bivalve GIFs That Will Blow Your Mind – Your Blown Mind Won’t Believe #6! first appeared on Deep Sea News.

The Tongue that Bites

Take this shell for example, so smooth it’s hard to tell if it was even in focus when photographed, is that of the Flamingo Tongue snail (Cyphoma gibbosum, Ovulidae). With satin pastel hues of pink and orange, the shell is worthy of a Miami Art Deco speakeasy, but the mantle that shrouds the shell adds a flair of early 1960’s cubist psychedelia. Most are barely

longer than an inch in length as adults, but size doesn’t matter since what they eat are the tiny, succulent coral-like polyps that make up the colonies within a sea fan. In the warm, shallow Caribbean Sea, a Flamingo Tongue Snail will graze on a sea fan, scraping and plucking out polyps, leaving a stark, lifeless trail behind. In areas where mollusk-eating fishes have been eliminated, the absence of their natural predators causes the snail population to explode, wreaking long-term and widespread damage to the slow-growing sea fans and the habitats they create.

Oyster Shooter

Who doesn’t love oysters? Ok, except vegetarians, and sure, those with shellfish allergies, but slurping down a raw oyster with a dab of Tabasco sauce and a squeeze of lime followedby an ice-cold lager is a marine biologist’s equivalent to a dose of Ativan. This water-worn little shell, less than two inches long, also loves oysters, but eats them in an entirely different way. The Japanese Oyster Drill (Ocenebra inornata, Muricidae) is far too small to eat an entire oyster, and too weak to pry open the shell, so it tries an entirely different method, one that you would expect in some freaky David Cronenberg film. The radula that in most species of snails are used as a rasp to scrape food off a

substrate, say algae off a rock or bits of meat off a dead fish. In this species, the radula is developed into an abrasive augur-like structure that can literally drill through the shell of other mollusks, and in particular, the sedentary oyster. Secretion of acidic enzymes through the proboscis containing the drill softens up the shell to make drilling quicker. Once the shell is perforated, the snail will then suck out the oyster’s fluids and soft tissues. Even more interesting, the evolution of a drill-like radula has been achieved independently in several different unrelated

lineages of predatory snails. But too many oyster drills can wreak havoc in an oyster bed, and this species in particular has been accidentally introduced into ecosystems far outside eastern Asia, proving them to be a serious invasive pest in regional shellfish industries.

Neritic Nosferatu
If you thought that a marine snail with an auger-like set of teeth drilling into an oyster to

suck out its juices was weird, I’m going to up the ante. As you’ve read in various postings about marine gastropods, you know the tooth-studded radula is a diverse and effective organ to acquire food. But scraping and drilling are just a few of the adaptations among marine snails, and this ruggedly handsome Cooper’s Nutmeg snail (Cancellaria cooperi, Cancellariidae) has another trick. Its sharp, almost scalpel-like teeth bite a small slit into their sleeping prey, and when the prey begins bleeding, their proboscis is pressed against the wound to casually sip the flowing blood. A vampire snail on its own seems earn

enough weirdness points, but it doesn’t stop there. Cooper’s Nutmeg seems to be an ectoparasite specializing on the California Electric Ray (Torpedo californica), a fish with high enough voltage to knock out any potential prey and foe alike, but somehow it doesn’t seem to detect the snail. Experiments in aquarium settings, as well as observations in the wild, suggests this snail specializes only on electric rays, with some observations showing over a dozen snails feeding simultaneously off a single ray, and has yet to be documented feeding on any other species of fish.

Cone of Silence

Last up in our series of marine gastropods and their strange adaptations for feeding is a good candidate for the next campy horror film. You may remember from past episodes that

cone snails (Conidae) have a highly-specialized harpoon-like radula and associated venom gland that makes them highly toxic predators. The Geography Cone (Conus geographus) is a slow, silent hunter on the midnight reefs where it seeks out sleeping reef fishes (yes, fish do sleep) by their acute sense of smell. Once within close range of a fish, the large mouth, really an expandable funnel-shaped shroud, releases a complex cocktail of nearly two dozen different paralytic toxins called the “nirvana cabal” including insulin that causes the prey to become lethargic by creating hypoglycemic shock, like the knock-out gas in an old James Bond movie. When the dazed fish is engulfed by the mouth, the harpoon is fired into the fish, quickly killing them. One look at the aperture of the shell shows an opening much wider than most other species of cone snails, and this allows the snail to swallow the entire fish into the main chamber of the shell. While their venom is primarily used for prey capture, it can be turned defensively on their predators. In fact, the Geography Cone is regarded as one of the most venomous of marine animals, and is responsible for no less than 30 documented cases of death in humans, though the actual number is likely much higher since traces of the venom are difficult to detect and effects of the toxins may mimic other more common causes of death, like heart attack.

The post Malacology Monthly: It Eats Whaaaat? first appeared on Deep Sea News.

Are you old enough to remember the show MTV Cribs, where a camera crew invades the home of a filthy-rich celebrity and takes annoyingly jumpy quick-shots of how awesomely decked-out and unnecessarily opulent their ‘crib’ is? Think about that approach, but with a Malacology Monday twist. Firing up a band-saw and with the warnings of my old school shop teacher “you’re gonna cut your thumb off” echoing in my head, our team will show you inside the ‘cribs’ of Malacology’s most interesting species.

High-Rise House
First up, the aptly-named Screw Turritella (Turritella terebra: Turritellidae) with a tall, twisting spire. For gastropods, the shell is a home that offers protection to withdraw into when needed, and as the muscled-mass of the snail grows, so too must the shell. The opening – or aperture – of the shell is the front-door, and new shell material is excreted by the fleshy mantle around the edge of this opening. As the door gets bigger, the shell wraps around itself as a twisted, ever-widening tube. What you see in the cross section is a ‘crib’ that starts off tiny when the snail is just a wee one, and gets larger with age. While not ostentatious enough to make it on MTV, it’s still a cozy and versatile home.

Cute as a Button
A peek inside the Commercial Topshell (Tectus niloticus, Trochidae) shows a low, tightly-twisting whorl, making the whole shell as a compact stout cone. The thick internal walls also provide strong structural support. Such a shape offers good architectural resistance from strong waves in shallow shores, and from shell-crunching fishes & crabs. From larger specimens, round shell disks are drilled to make buttons, hence the name Commercial Topshell, not that it is especially good at banking or international commerce. Since only a few buttons can be drilled from each shell, this species is heavily collected in the Indo-Pacific region where it lives, and since its meat is delicious, it has been fished-out in much of its range. Several countries are developing captive-breeding facilities to raise them commercially, and other programs employ captive hatcheries that release the young back in the wild to supplement the natural population. In many areas though, the main way to promote the population of the Commercial Topshell is to kill off their wild predators, like porcupine fishes, wrasse, bat rays, and crabs. Not such an ecologically sound approach especially since a single darned coconut can make more buttons than a dozen shells.

Home Security
Next we burst into the home of the Strawberry Conch (Strombus luhuanus: Strombidae), one of the smallest but most abundant conch species in the Indo-Pacific. Here we see the shell growing tightly around most of the body, leaving very little of the spire exposed. The aperture of the shell is very long and narrow, but since the resident snail has no internal hard parts, it can flatten its foot, head, and mantle to squeeze through that skinny opening. Such a thin front door is an adaptation against large predatory crabs, nature’s home-invasion robbers. In shells with a larger openings, crabs don’t politely knock, but hold the shell tight with one claw, and with the other, they jab it into the aperture and break the opening away. As the snail withdraws deeper into the shell, the crab just keeps turning and breaking the whorl of the shell until it reaches its prey. With the Strawberry Conch, their security system consists of this narrow opening that prevents a crab from inserting its claw in the first place, and the thickened lip around this opening provides extra strength to prevent the initial breakage of the aperture, keeping the snail safe inside

House of a Hundred Rooms
In this, our last visit through the dwellings of mollusks, we visit the palatial estate of the Chambered Nautilus (Nautilus pompilus; Nautilidae), with a grand array of ever diminishing luminous pearlescent back-rooms. As we saw during our tour through the rather Spartan dwellings of gastropods, the living chamber for the snail is a continuous tube that spirals around an axis, increasing in length and diameter as the animal grows. While the Chambered Nautilus develops in a somewhat similar way, the living chamber holds the mass of the tentacled landlord, but as the shell grows, the previous back-end of the living chamber is walled-off with a shiny layer of nacre. These rooms are connected by a spiral tube, the siphuncle (use that term in your next Scrabble match) that balances fluids, salts, and gasses, ultimately making each empty room an internal flotation device. Gastropods slowly drag their home along the sea floor like low-class campers, but the Chambered Nautilus uses blasts of water from its siphon to push the shell through the open water like a sporty, speedy, jet-powered blimp. In deeper water, the wall between each chamber strengthens the shell, preventing a disastrous implosion. Chambered Nautilus, I like your style.

The post Malacology Monthly: Inside-Out first appeared on Deep Sea News.

Scorpion Without a Sting

This leggy shell belongs to a group of gastropods called the Spider Conchs, and this particular species is the Scorpion Spider Conch (Lambis scorpio), which can neither bite nor sting. The group gets its name from the leg-like extensions along the edge of the expanded opening of the shell (aperture) that serve no function in locomotion. Living in the intertidal and shallow subtidal mud, sand, and coral rubble where the surge of waves can be intense, researchers believe these spines serve to prevent the snail from rolling on the bottom. As an added benefit, long, thick spines could make it more difficult for mollusk-eating fish to eat the Scorpion Spider Conch. But as nobody has ever conducted any field studies or laboratory simulations of how these spiny shells actually function, they are untested assumptions. If scientists knew everything, there would be no work for graduate students.

Spiny Shield

Limpets rarely get much respect among malacologists, let alone shell collectors, yet they have a subtle magnificence. I bring you the Bearded Limpet (Scutellastra barbara; Patellidae). Mollusks that live in the intertidal zone are the cage-fighters of the invertebrate world. You’ve got to be extra tough to withstand tons of force from a crushing wave, survive the hot and dry exposure from low tide, and have sure-fire ways to avoid being eaten by predators both on the land and in the water. This shell has a series of strong ridges that radiate out from the crest of this pyramid-like shell to the outer margins of the shell. Architecturally, these ridges act as girders not just strengthening the shell, but directing the power of a breaking wave to the outside edge of the shell. This causes the power of the wave to be divided across the shell along these girders, but since these ridges end in spines that are in contact with the rocks, the wave force actually causes the shell to be pressed against the rock, holding it in place as the wave is breaking around the shell. Further, the bumpy, spiny edge of the shell could also make it harder for limpet enemy number one – the African Oystercatcher – to eat it. The bill of the oystercatcher is shaped like the flat end of a standard screw driver, and the oystercatcher wedges this sharp edge under the shell and pries it off, flips it over, and scrapes out the fleshy tidbits. The uneven spiny edge makes it much more difficult for the oystercatcher to slip the bill underneath the shell, and theoretically a few more Bearded Limpets survive to pass on this morphology to the next generation.

Twice the Spines, Twice the Fun

The Spiny Oysters (Spondylus: Spondylidae) such as this dandy Spondylus foliaceus, are a widespread group in tropical and subtropical waters, shallow and deep seas, with a diversity of colors and shapes, but they are all united in the spines, thorns, and prickly bits that cover their shell. The function of these spines, as imagined by unimaginative malacologists, it to protect the oyster from piscine predators, but that’s what they always say. Three other possible ways that could potentially increase the survival of the spiny oysters are as follows: (1) these spines could act to deter the settling of barnacles, anemones, and even other oysters on their shell. Acting as a figurative layer of barbed-wire the spines keep other large invertebrates from plopping-down on their shell and growing on them, weighting them down, and competing for food; (2) the expanded surface area these spines provide could promote the settlement and growth of other small marine organisms. Algae, bryozoans, and encrusting sponges, could provide a natural camouflage to better conceal these oysters on the sea floor; and (3) these spines could act as a ‘baffle’ to slow water flowing around the clam. As you all remember from your hydrophysics courses, moving water carries objects (sand particles, plankton, delicious detritus, etc.), and the faster the water moves, the larger particles and the greater number of particles the flow can carry. If there are impediments to water flow, such as dozens of spines on an oyster’s shell, the water slows and drops its particles. So, the spiny oyster’s spines may act to slow moving water around it, and that water would drop its suspended detritus and plankton right around the edge of the shell where the oyster is drawing in that water to filter out a meal. Or maybe it’s just to deter fish from eating them after all.

Shell Superstar

Behold the Japanese Star Turban shell (Guildfordia yoka; Turbinidae), a flat and radially spiny gastropod from the western Pacific Ocean that looks like a nasty weapon hurled in a kung-fu movie. One hypothesis concerning their spines is that it helps to distribute the weight of the snail outward so that it doesn’t sink into the soft deep-sea muds where it lives. Where broad, flat spines might accomplish this feat, their thin, narrow spines would seemingly cut into the soft mud, offering no real support for the weight of the shell in the center. But dang it if those spines don’t give up clues themselves; because they often show signs of breakage and regeneration, like one of the spines seen in this shell, they are likely for protection from predators. If the spines don’t actively repel foraging deep-sea fishes by a painful jab in the roof of the mouth, the spines may simply make the snail too big to even swallow in the first place. When the Japanese Star Turban survives a potential attack with a few spines broken, the snail will repair or regrow the protective spines to live another day.

Spines Fit for a Goddess

Sorry that I didn’t mention there would be a final exam for the end of this post, so sharpen that No. 2 pencil. Spines on shells, much like a Swiss army knife, can serve one or many functions. They deter predators, strengthen the shell, and support the animal in various ways. But this gastropod shell, the Venus Comb Murex (Murex pecten; Muricidae) is the most glorious example of spines. As the name might suggest, it is the natural comb that keeps a sexy Roman goddess’ hair smooth and manageable. After all, as legend has it, Venus was born of sea foam, and you can imagine what ruin the tides can do to her hairdo. But no, none of the ancient texts or depictions in paintings, mosaics, or bas-reliefs show Venus using this shell as a styling tool. So then, what evolutionary, ecological, and/or morphological function do you expect the spines to serve? Watch the video below for some clues:

The post Malacology Monthly: Spines and How to Use Them first appeared on Deep Sea News.

Bivalves: clams, scallops, oysters, cockles, and mussels, have rich lives and complex evolutionary histories far beyond the deep-fryer. Here are vignettes of four bivalves that provide a small glimpse into their world. So next time you order the frutti di mare linguini, ponder for a second what you are about to eat.

Smart Scallops
Edward ‘Doc’ Ricketts, renown marine biologist and friend to full-time novelist and part-time alcoholic John Steinbeck, once stated: “next to the octopus, the scallop is the ‘cleverest’ of all the mollusks”. While I don’t entirely agree with that remark, I do concur that scallops are perhaps the most interesting of all the bivalves, like these polychromatic Noble Scallops (Mimachlamys nobilis). What makes scallops (Pectinidae) unique among the bivalves are their

baby-blue eyes, ones that would give a Frank Sinatra a run for his money. Surrounding the open-end of the shell in upper and lower rows as a vigilant arcade, these simple peepers can detect changes in light and perceive basic movement, warning the scallop of advancing predators. Their response is to flee by snapping the two sides (valves) of their shell like crazy zombified castanets, scurrying in zig-zagging movements away from the imminent threat by forcing out strong spurts of water every time the shell snaps shut. While these sudden movements may not be guided in a specific direction, the main goal is to get the scallop way from what may hope to eat it, which usually propels them far enough from harm’s way.

Adaptations for this snap-and-zag escape consist of a wide, flexible hinge at the back end of the shell, and a single adductor muscle that can quickly pull the two halves of the shell together. It is this muscle, making about 20% of the soft tissue inside the shell, that one eats as the ‘scallop’ in a seafood platter, with most of the remaining flesh discarded. Most other non-western countries relish the extra innards of the scallop, especially the swollen and succulent gonads during the scallops’ mating season, but those in the more industrialized nations can afford to waste what is perfectly edible. And ironically, while the tasty adductor muscle may be the key in a scallop’s escape from a predator, it doesn’t work so well when trying to flee the path of a 30’ beam trawl dragged along the bottom of the sea.

Boring, Boring, Boring…

Clams can be boring, really boring. No, really, boring. Some species bore into packed mud and some bore into wood or even whale bone, but the Warty-necked Piddock (Chaceia ovoidea) can actually bore into solid rock. Larval piddocks settle into small cracks or existing holes in the rock, and as the shell grows, the posterior portion of the shell develops rows of rough ridges that act as a rasp, and the clam uses it’s muscular foot to bump and grind, literally drilling into the sandstone, shale, and limestone on the ocean floor. As the clam continues to grow in size, it’s burrow becomes an inverted funnel, with the original hole opening to the outside, and a larger interior den that increases in size as the clam’s shell grows and constantly scrapes and remodels the inside of its home. Though it can never escape its clam cave, it lives a simple life of a filter feeding bivalve by extending two large fleshy

siphons out the front door that look like a tunicate. The larger incurrent siphon (the gazin) sucks water and suspended food into the body for filtering, and the smaller excurrent siphon (the gazout) flushes the filtered water outside of the clam’s shell. While their means of feeding isn’t impressive, their bivalve superhero ability to literally drill into solid rock should convince some of you that boring clams certainly aren’t boring. But what about sex? Celibate clams cloistered in a stone cell?  Easy, fertilization is external, with males & females releasing sperm and egg simultaneously during particular spring tides.

Motherly Love
For Mother’s Day, we in the Malacology Monday team honor all those mothers out there, present and past. I experienced much too recently the impermanence of one’s mother and the void it leaves in the heart, so perhaps this True Heart Cockle may fill that hole for those of us who have lost their mother. This heart is full of motherly love. The genus name Corculum means ‘darling heart’ in Latin, and the species name cardissa is the Greek word for ‘female heart’. Their family of bivalves is the Cardiidae, meaning ‘heart’ in Greek, and they are a member of the larger taxonomic group Veneroidea, stemming from the Latin venereus, derived from Venus, the goddess of love, which is most likely how you were conceived by mom in the first place. But Corculum cardissa is not like most mothers. The True Heart Cockle is a hermaphrodite, not an uncommon method of reproduction in the invertebrates, but a rare method of producing young among the bivalves. As Corculum expels an egg, it is carried away by the currents and rapidly develops over the next two days into a miniature copy of the mother it will never see again. In the meantime, mother has an adopted family of her own microscopic dinoflagellate algae living in her tissues. Her semi-transparent shell acts as a tiny greenhouse protecting these adoptees who pay their respects by manufacturing food through photosynthesis that supplements what other food particles she strains from seawater through her gills. What she lacks as an absentee mother for her own spawn, she makes up for as the caretaker to hundreds of tiny dinoflagellates.

Heavyweight Champion of the Bivalve World

The Malacology Monday team was recently on expedition deep into tropical malacology. The highlight of our explorations along the Great Barrier Reef were dives with the giant clam (Tridacna gigas), from wee ones smaller than an Oreo cookie, to some massive old guardians of the reef that were near record size. This clam is the largest bivalve alive today, with their shell reaching over 1.3 meters (4.2 feet) wide and weighing a whopping 331 kg.(730 lbs). While they are indeed clams, they live more like corals, housing symbiotic photosynthetic zooxanthellae in their large, brightly-colored fleshy mantle, which look like Mick Jagger’s swollen lips after being decked by an enraged Bianca. But these lips, like the mantle of the Heart Cockle (above) house the millions of

tiny algae that convert tropical sunlight into food energy, sharing it with the clam and supplementing the clam’s diet of filtered detritus and plankton to keep it alive. For that reason, these clams must live in the warm and intensely light shallows of the tropics where they can be abundant enough to be the dominant component of some reefs, even exceeding coral in biomass and coverage. While the giant clam population around the Great Barrier Reef appears stable, with even the largest clams seemingly abundant, pollution, sedimentation, dredging, and collecting clams directly for food or sale into the curio trade, giant clams elsewhere are declining or even wiped-out entirely. Australia, however, has been pioneering the aquaculture of giant clams, and have successful long-term projects to re-populate reefs in the South Pacific with these massive mollusks.

The post Malacology Monthly: A Look at Bivalves, From Both Sides Now first appeared on Deep Sea News.

Like seashells but are sick of social media?  Hate Facebook but need a hearty dose of marine invertebrates?  Want a bigger malacological meal rather than tiny tidbits of mollusk-based science? Do not worry, you can get all of the “Malacology Monday” posts from the Deep Sea News Facebook page right here on the official DSN website in a tidy & convenient monthly digest without submitting to The F-Book. Here’s what happened last month:

Malacology Monday starts big, really big.
Syrinx auranus, alternately the Australian Trumpet, the Golden Trumpet, and the False Trumpet is the world’s largest living shelled gastropod. This snail is rumored to reach lengths of up to a meter long, but research by members of Deep Sea News can only verify the largest as 72.2 cm (2.36 feet). This specimen from Indonesia is merely 58.2 cm, still nearly two feet in length. What does a snail this size eat? These carnivores tackle large polycheate worms that may grow over a meter in length.

Cloth of Gold, Cloth of…Murder!
In a 1972 episode of Hawaii Five-0, this species of marine snail was used as a murder weapon by a grieving father avenging the death of his daughter at the hands of seedy pornographers. While cone shells have a specialized harpoon & hypodermic needle-like apparatus to deliver toxins to kill their prey, most species are relatively harmless to humans. But some cone species, like the Cloth of Gold, or Textile Cone (Conus textile), can potentially deliver a fatally paralyzing dose of conotoxin to a person handling a live one. However, death can be quite slow, unlike the near-instantaneous demise depicted by those lowlife criminal scum. But not wanting to get nabbed by McGarrett, the mollusk-wielding murderer then turns the venomous gastropod on himself, and the scene fades, with his lifeless body sinking below the placid Oahu waters. Cue the 5-0 theme music…

Bulbous Bling
The Golden Cowrie (Lyncina aurantium) once adorned the kings of Melanesia, and were used as status symbols and units of trade. Their simple beauty and apparent rarity later made them highly sought by museums and private collectors alike, with the shells fetching hundreds of dollars each. It was their cryptic nature and inaccessibility that kept this species safe for a while. Once it was discovered that they were nocturnal, and inhabited the deeper outer reefs from 30-40 meters, they became targeted for the international shell trade. In in some areas, especially smaller islands in the Philippines, specialized Golden Cowrie divers collected them by the hundreds, driving their prices down yet causing local populations of Golden Cowries to plummet. Conservation and management plans are being considered in some areas of the southwest Pacific and Indian Ocean range, but so little is known about their biology that current management plans may not be effective.

Ceremonial Conch
The rather unremarkable looking shell below is actually quite remarkable in two ways. The incredibly thick shell of the Eastern Pacific Giant Conch (Lobatus galeatus) makes it one of the heaviest marine gastropods for its size. But this particular specimen had its spire cut off and made into a pututo, a ceremonial trumpet, and was found in a burial chamber of a lower class member of the Chimu culture of the north-central coast of Peru, about 1300 A.D. Higher-class people often had ornately-carved shells, sometimes with inlays of gems, as part of their burial offerings. The Giant Conch on the right from the Brooklyn Museum is from the older Chavin culture of Peru (about 300 BC) and shows a carving of a man blowing a conch as part of a ceremonial ritual.
All photos, unless otherwise noted, are by Douglas J. Long/Deep Sea News.

The post Malacology Monthly: Pilot Episode first appeared on Deep Sea News.

You already know that Deep Sea News provides expert reporting, in-depth analysis, first-person research, and sarcastic mockery of contemporary topics relevant to our ocean world. Unlike other popular science sites that can be wildly imaginative and dangerously inaccurate, DSN’s crew of scientists cut through the pop-science b.s. and re-posted misinformation to deliver ocean news that you can trust.

But did you know the DSN Facebook site provides even more delicious science nuggets each week for your inquiring mind to chew and savor? Beginning this week, as a premium for our Facebook friends, each and every Monday from now until eternity* will feature the shell of a different marine marine organism in an ongoing DSN internet event called Malacology Monday.

Dipping into the vast marine science collection from the Lobos Marinos International Marine Science (& Cocktails), we will bring you the dazzling array of evolutionary innovations, complex architecture, and endless aesthetics that sea shells deliver. For each species featured we will also communicate bona-fide scientific information and curious facts about the ecology and adaptations of extant and extinct mollusks, as well as the long human history with marine shellfish and their impact on our own culture.

If you like mollusks, and in particular malacology, this is a much-need intravenous drip of taxonomic enlightenment and morphological bliss, and if you aren’t yet in the cult, Malacology Monday will be the digital gateway drug to a soul fulfilling and mind expanding appreciation of our underwater world. So start each week with a stiff shot of mollusks on Deep Sea News’ Facebook Page.

*Eternity not exclusive of time away for expeditions, conferences, vacation, last-minute pre-deadline grant-writing, finals week grading, benders, mandatory time at the honor rancho, amnesia, malaise, or the untimely demise of the concept’s host.

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The post Malacology Monday first appeared on Deep Sea News.