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Clam

Clams are bivalve mollusks belonging to the class Bivalvia in the phylum Mollusca, characterized by a soft-bodied invertebrate enclosed within a two-part hinged shell composed of calcium carbonate.^[1] These shells, secreted by the mantle tissue, protect the clam's body and can vary widely in shape, size, and color depending on the species, with common examples including hard clams (Mercenaria mercenaria), softshell clams (Mya arenaria), and giant clams (Tridacna spp.).^[2] Primarily marine dwellers, clams inhabit intertidal zones, subtidal sediments, and deeper ocean floors worldwide, though some species, like fingernail clams, thrive in freshwater environments.^[1]^[3] Biologically, clams are filter feeders that draw in water through an incurrent siphon, trapping plankton, algae, and organic particles on their gills using mucus and cilia before sorting and digesting the food via labial palps.^[2] They lack a radula, the rasping tongue found in other mollusks, and instead rely on a muscular, hatchet-shaped foot for locomotion, burrowing into sand or mud to evade predators and anchor themselves.^[2] Reproduction varies by species but often involves external fertilization, with larvae free-swimming before settling and metamorphosing into juveniles; growth rates are slow, taking years to reach harvestable sizes in many commercial species.^[4] There are approximately 9,200 known bivalve species, with clams representing a significant portion adapted to diverse habitats from tropical coral reefs to Arctic shores.^[1] Ecologically, clams serve as keystone species by filtering large volumes of water—up to 50 gallons per day for larger individuals such as oysters and giant clams—removing excess nutrients and suspended particles, thereby improving water clarity and mitigating harmful algal blooms.^[5]^[6] They provide habitat for smaller organisms within their burrows and act as prey for birds, fish, and mammals, supporting food webs in coastal and estuarine systems.^[7] Economically, clams underpin global fisheries and aquaculture, generating billions in revenue; for instance, as of 2022, U.S. shellfish aquaculture production, including clams, totaled approximately 50 million pounds, contributing to coastal community livelihoods through harvesting, processing, and ecotourism.^[8] However, populations face threats from overharvesting, habitat loss, pollution, and climate change impacts like ocean acidification, which weakens shell formation.^[4]

Taxonomy and Diversity

Definition and Classification

A clam is a common name primarily used for certain edible, burrowing bivalve mollusks that inhabit marine and estuarine sediments, belonging mainly to families such as Veneridae (venus clams) and Myidae (softshell clams), and distinguished from non-burrowing bivalves like scallops (family Pectinidae) or oysters (family Ostreidae).^[9]^[10] The term "clam" derives from the Old English word clamm, meaning a bond, fetter, or clamp, which alludes to the tight closure of the bivalve's two shells.^[11] Taxonomically, clams are classified within the kingdom Animalia, phylum Mollusca, and class Bivalvia (established by Carl Linnaeus in 1758), with many species falling under subclasses such as Heterodonta (for heterodont clams with prominent hinge teeth) and Pteriomorphia (though the latter includes more diverse forms like oysters).^[12]^[13] Key distinguishing traits of clams include bilateral symmetry, a pair of hinged calcareous shells (valves) enclosing a soft body, and extensible siphons that enable filter-feeding on suspended particles without leaving the burrow.^[14] Historically, bivalve classification began with Linnaeus's Systema Naturae in 1758, which grouped them under the order Testacea, but subsequent revisions in the 19th and 20th centuries separated Bivalvia as a distinct class based on shell and anatomical features.^[12] Modern taxonomy has been refined through molecular phylogenetics, incorporating mitochondrial and nuclear gene analyses to resolve evolutionary relationships and revise subclass boundaries, revealing Bivalvia's diversification into approximately 9,200-10,000 extant species, with burrowing heterodont bivalves (commonly called clams) comprising a significant portion in diverse families.^[15]^[10]

Major Groups and Notable Species

Clams, belonging to the class Bivalvia within the phylum Mollusca, are diverse and primarily marine bivalves, with major taxonomic groups organized into families that reflect adaptations to various substrates and environments.^[10] One prominent family is Veneridae, known as venus or hard clams, which includes approximately 800 species characterized by thick, equivalved shells and a cosmopolitan distribution in marine and estuarine habitats. Notable examples within Veneridae include the northern quahog (Mercenaria mercenaria), a hardy species native to the western Atlantic from the Gulf of St. Lawrence to the Gulf of Mexico, valued for its commercial harvest and reaching sizes up to 12.7 cm. Another key family is Myidae, comprising soft-shell or mud clams with thin, fragile shells and elongated siphons adapted for burrowing in soft sediments; Mya arenaria, the soft-shell clam, exemplifies this group, occurring in temperate to subarctic waters of the North Atlantic and Pacific, where it inhabits intertidal mudflats and can grow to 15 cm. The family Cardiidae, or cockles, features heart-shaped, ribbed shells suited for shallow, sandy bottoms; Cerastoderma edule, the common cockle, is a widespread European species found in intertidal zones from the North Sea to the Mediterranean, typically measuring 2-6 cm and harvested for food. Among notable species, the giant clam (Tridacna gigas) stands out for its massive size, reaching up to 1.5 m in length and over 200 kg, with a distribution confined to the tropical Indo-Pacific coral reefs from the South China Sea to the Great Barrier Reef.^[16] This species exhibits a unique evolutionary adaptation through symbiosis with zooxanthellae algae (Symbiodinium spp.), photosynthetic dinoflagellates housed in its mantle tissues that provide the majority of the clam's energy, up to 100% in large individuals, via translocated photosynthates, enabling rapid growth in nutrient-poor waters.^[17] The razor clam (Ensis siliqua), in the family Pharidae, is recognized for its elongated, blade-like shell up to 20 cm long and its rapid burrowing ability—up to 70 cm per minute—allowing it to inhabit dynamic sandy substrates in temperate North Atlantic and European coastal waters. The Manila clam (Ruditapes philippinarum), from Veneridae, is a small (up to 8 cm), oval-shelled species originally from the temperate western Pacific coasts of Asia, but widely introduced globally for aquaculture, establishing populations in North America, Europe, and Australia through deliberate stocking and natural dispersal. Clam distributions vary markedly between temperate and tropical regions, with temperate zones hosting burrowing species like those in Myidae and Veneridae in cooler, sediment-rich coastal areas, while tropical waters dominate for larger, reef-associated forms such as Tridacnidae (giant clams).^[18] Hundreds of clam species are edible and commercially significant worldwide, supporting fisheries and aquaculture that harvest species adapted to diverse salinities and temperatures.^[19] Conservation concerns affect key species, particularly giant clams; Tridacna gigas is classified as Critically Endangered by the IUCN due to overexploitation, habitat loss, and an estimated 84% population decline, while T. derasa is listed as Endangered and T. squamosa as Least Concern (as of 2024 IUCN assessments) from similar pressures in the Indo-Pacific. Recent 2024 IUCN assessments, informed by genetic and population studies, have elevated the status of several giant clam species, highlighting ongoing threats.^[20]^[21]^[22]

Anatomy and Physiology

Shell and External Features

The shell of clams, like other bivalves, is primarily composed of calcium carbonate in the form of aragonite or calcite crystals, arranged in layered structures that provide protection and support.^[23] The outermost layer, known as the periostracum, is a thin, organic covering made of proteins and chitin that protects the underlying mineral layers from erosion and boring organisms.^[24] Shell morphology varies across species; for example, razor clams (Ensis spp.) exhibit elongated, smooth shells adapted for rapid burrowing, while hard clams or quahogs (Mercenaria mercenaria) have thicker, more rounded shells with subtle concentric ridges formed by growth increments.^[25] The hinge structure at the dorsal margin of the shell consists of interlocking elements that maintain valve alignment during opening and closing. In most clams, this is a taxodont hinge featuring numerous small, similar teeth arranged in one or two rows on either side of the umbo, preventing lateral slippage of the valves.^[10] Closure is achieved by one or two powerful adductor muscles, which contract to draw the valves together tightly, enabling the clam to resist predation and environmental stresses.^[26] External appendages include paired siphons formed by fused mantle lobes: the inhalant siphon draws in water laden with food particles and oxygen, while the exhalant siphon expels filtered water, waste, and pseudofeces.^[27] The foot is a muscular, protrusible organ used for locomotion and burrowing, capable of extending to approximately the length of the shell in some species to anchor and propel the animal into sediment.^[28] The mantle edges, particularly the outer fold, secrete new shell material incrementally, adding to the valves' margins and thickening the inner nacreous layer over time.^[29] Clam sizes span a wide range, from tiny pea clams (Pisidium spp.) measuring less than 1 cm in length to giant clams (Tridacna gigas), which can exceed 1.5 m across and weigh over 200 kg.^[16] Shells often bear annual growth rings, analogous to tree rings, formed by periodic slowdowns in calcification due to environmental factors like temperature and food availability; these rings allow age estimation by counting distinct bands in cross-sections.^[30]

Internal Organs and Functions

Clams, like other bivalve mollusks, possess an open circulatory system in which hemolymph—a fluid analogous to blood—bathes the organs directly rather than being confined to vessels.^[31] The heart, located in the pericardial cavity near the adductor muscles, consists of a single ventricle and two auricles that receive oxygenated hemolymph from the gills.^[27] This system efficiently distributes nutrients and oxygen while collecting waste, with hemolymph circulating through open sinuses before returning to the heart. The digestive system of clams is adapted for filter-feeding on suspended particles such as phytoplankton and detritus. Water enters the mantle cavity through the incurrent siphon and passes over the ctenidia, where mucus-covered filaments capture food particles that are then transported to the mouth.^[32] Labial palps, fleshy folds near the mouth, sort edible particles from pseudofeces—rejected material that is expelled. Inside the stomach, a crystalline style, a rotating mucoprotein rod secreted by a style sac, continuously mixes food with digestive enzymes, facilitating breakdown.^[33] The intestine absorbs nutrients, completing digestion before waste is released through the excurrent siphon. Adult hard clams (Mercenaria spp.) can filter 7 to 8 liters of water per hour, processing significant volumes to meet nutritional needs.^[32] The nervous system in clams is decentralized, lacking a centralized brain, and consists of three pairs of ganglia connected by nerve cords: cerebral ganglia controlling the mouth and senses, pedal ganglia innervating the foot for locomotion and burrowing, and visceral ganglia overseeing internal organs like the gills and digestive tract.^[34] These ganglia coordinate basic reflexes, such as rapid shell adduction in response to threats via the anterior and posterior adductor muscles, mediated by sensory inputs from statocysts, osphradia, and tactile receptors.^[35] Respiration and excretion are integrated functions primarily involving the ctenidia and kidneys within the mantle cavity. The ctenidia, paired gill structures lined with beating cilia, not only capture food particles but also facilitate gas exchange by diffusing oxygen into the hemolymph from incoming water.^[36] A pair of kidneys (nephridia) filters metabolic wastes from the hemolymph, producing urine that is discharged through nephridiopores into the mantle cavity and expelled via the excurrent siphon, maintaining internal homeostasis.^[36] This dual role underscores the efficiency of the mantle cavity as a multifunctional chamber for feeding, respiration, and waste elimination.

Life Cycle and Reproduction

Spawning and Fertilization

Clams primarily reproduce sexually through broadcast spawning, where eggs and sperm are released into the water column for external fertilization. Most clam species, such as the Manila clam (Ruditapes philippinarum), are gonochoristic, possessing separate sexes, while others like giant clams (Tridacna spp.) are simultaneous hermaphrodites that release sperm before eggs to avoid self-fertilization.^[37]^[38] This reproductive strategy dominates in marine bivalves, enabling widespread dispersal but relying on synchronized spawning events among individuals.^[39] Spawning is triggered by environmental and chemical cues, including rising water temperatures, lunar cycles, and pheromones released by conspecifics. In temperate species like the Manila clam, spawning peaks during summer when temperatures reach 20–22°C, with partial spawning occurring from May to September as seawater warms from 11°C to 20°C.^[40]^[41] Lunar periodicity influences timing in some venerid clams, such as Meretrix meretrix, where reproductive stages align with moon phases to enhance synchronization.^[42] Chemical signals, including sperm or tissue extracts, can induce spawning in hatchery settings for species like giant clams.^[43] Gamete production is prolific; female Manila clams can release up to 3.4 million oocytes per individual during a spawning event, with fecundity increasing with body size.^[44] Fertilization occurs externally in the water column, where sperm must locate eggs amidst rapid dilution, resulting in success rates often below 10% at natural densities due to sperm motility limitations and short lifespans.^[45] In giant clams, hermaphroditic individuals broadcast gametes sequentially, with external fertilization yielding trochophore larvae within hours.^[38] Optimal conditions include salinities above 20 ppt, typically 24–31 ppt for Manila clams, as lower levels impair gamete viability and spawning.^[46]^[47] Overfishing reduces population density, exacerbating dilution effects and lowering fertilization success through gamete wastage in broadcast spawners.^[48]

Larval and Juvenile Development

Following fertilization, clam eggs develop into free-swimming trochophore larvae within hours, typically measuring 40-60 μm in size. These larvae, which lack a shell and rely on yolk reserves for initial nutrition, typically develop into the veliger stage within 24 hours, where they begin filter-feeding on plankton using a ciliated velum.^[49]^[50] The veliger stage, characterized by the development of a ciliated velum for locomotion and feeding, as well as the onset of a hinged shell (often called the D-stage larva at around 160 μm shell length), lasts 1-2 weeks depending on temperature and food availability. During this period, larvae grow to 200-300 μm while actively swimming in the water column to disperse.^[51]^[38] As veligers mature into the pediveliger stage (around 200-500 μm shell length), they develop an eye spot and a foot, enabling them to sense and select suitable substrates for settlement, such as fine sediments or hard surfaces. Settlement occurs when pediveligers attach to the substrate using temporary byssal threads secreted from the foot, marking the onset of metamorphosis from planktonic to benthic life. This transformation involves resorption of larval structures like the velum and significant remodeling of the body, resulting in a juvenile form approximately 300 μm in size that begins to resemble the adult.^[52]^[53] The process typically takes 8-10 days from fertilization to settlement under optimal conditions.^[50] Juveniles, now postlarvae, initiate burrowing into the sediment shortly after settlement, often at sizes around 1 mm shell length, using their foot to probe and anchor while developing stronger byssal attachments initially. Growth is rapid in the first year, with juveniles reaching several millimeters in length under favorable temperatures and food supply, though rates vary by species and environment. Sexual maturity is attained in 1-3 years; for example, soft-shell clams (Mya arenaria) typically mature in about 1.5-2 years at shell lengths of 20-30 mm.^[54]^[55]^[56] The larval and early juvenile stages are highly vulnerable, with mortality rates often exceeding 90-99% in the wild due to predation by zooplankton and fish, as well as dispersal by currents that prevent settlement. Physical factors like temperature fluctuations and starvation further contribute to these losses, making recruitment highly variable. In aquaculture, hatchery rearing mitigates these risks by providing controlled environments with optimal feeding (e.g., algae cultures) and protection from predators, achieving survival rates of 50-80% to the pediveliger stage and enabling reliable seed production.^[57]^[58]

Ecology and Distribution

Habitats and Geographic Range

Clams primarily inhabit soft-bottom marine environments, burrowing into sandy or muddy substrates in intertidal and subtidal zones at depths typically ranging from 10 to 50 cm. These preferences allow them to exploit nutrient-rich sediments while minimizing exposure to surface disturbances.^[59]^[60] They exhibit broad environmental tolerances, thriving in salinities of 10 to 35 ppt and temperatures from -2°C to 30°C, which enables survival across diverse coastal conditions from polar to subtropical regions.^[61]^[62]^[63] Geographically, clams have a cosmopolitan distribution, occurring in all major ocean basins, though species diversity peaks in the Indo-Pacific. For instance, the northern hard clam (Mercenaria mercenaria) ranges along the western North Atlantic from the Gulf of St. Lawrence in Canada to the Gulf of Mexico.^[64]^[65] Zonation patterns vary by species and habitat; littoral forms such as cockles (Cerastoderma spp.) occupy wave-exposed intertidal areas on clean sands or muddy gravels in the middle to lower shore, while some families like Vesicomyidae extend to deep-water environments up to 2000 m in bathyal and abyssal zones.^[66]^[67]^[68] Burrowing serves as a key adaptation, shielding clams from desiccation during low tides and enabling residence in fluid soft sediments, often facilitated by extendable siphons that reach the sediment-water interface for feeding and respiration without full emergence.^[69]^[70]

Ecological Roles and Interactions

Clams play a pivotal role in marine and estuarine ecosystems as filter feeders, actively pumping water through their gills to capture phytoplankton, detritus, and other suspended particles, thereby removing substantial amounts of organic matter from the water column. This process enhances water clarity by reducing turbidity and algal blooms, with individual littleneck clams (Protothaca staminea) capable of filtering up to 4.5 gallons of seawater per day, and dense populations collectively processing large volumes to support ecosystem health. Through biodeposition, clams deposit nutrient-rich pseudofeces on the sediment, facilitating nutrient recycling, while their burrowing activities promote bioturbation, which mixes sediments and increases oxygen penetration depths by up to several centimeters, alleviating anoxic conditions in benthic layers.^[71]^[72]^[73] As integral components of food webs, clams serve as prey for a diverse array of predators, including birds such as oystercatchers (Haematopus spp.), which probe sediments to extract them, various fish species like angelfish and triggerfish, and marine mammals including sea otters. To counter these threats, many clam species employ behavioral defenses, such as rapid burial into sediments using their muscular foot to evade detection, and chemical protections where certain bivalves accumulate saxitoxins—neurotoxins produced by dinoflagellates like Alexandrium spp.—which can deter predation and even confer resistance in some populations through genetic adaptations in sodium channels.^[74]^[75]^[76] In symbiotic relationships, particularly among giant clams (Tridacna spp.), zooxanthellae algae hosted within their mantle tissues perform photosynthesis, supplying up to 50-70% of the host's energy needs through translocated photosynthates in exchange for nutrients and protection. These clams further contribute to ecosystem structure by accreting calcium carbonate shells at rates of millimeters to centimeters per year, providing habitat complexity and supporting coral reef frameworks through long-term bioerosion resistance and structural integration.^[77]^[78]^[79] Clams also function as indicator species for environmental stressors, accumulating heavy metals like mercury, copper, and cadmium in their tissues via filter feeding, which reflects local pollution levels and enables biomonitoring in coastal waters. Their sensitivity to ocean acidification impairs shell formation by disrupting calcium carbonate precipitation, making them valuable sentinels for assessing pH changes and associated ecological risks.^[80]^[81]^[82]

Human Uses and Interactions

Culinary Applications

Clams have been a staple food source for humans since Paleolithic times, with archaeological evidence from shell middens indicating consumption as early as 10,000 years ago in various coastal regions.^[83] These ancient refuse heaps, composed primarily of clam shells, demonstrate the shellfish's role in prehistoric diets, particularly among coastal hunter-gatherer societies. Today, clams remain a globally significant seafood, with aquaculture production exceeding 4.5 million metric tons as of 2022, contributing to a market valued at approximately $10 billion.^[19]^[84] Nutritionally, clams are nutrient-dense, providing high-quality protein at about 15 grams per 100 grams of cooked meat, along with essential omega-3 fatty acids, iron, and vitamin B12, while being low in fat and calories.^[85] These nutrients support heart health, immune function, and red blood cell production, making clams a valuable component of balanced diets. However, as filter feeders, clams can bioaccumulate toxins such as paralytic shellfish poisoning (PSP) from harmful algal blooms, posing health risks if not properly monitored.^[86] Basic preparation methods emphasize safety and texture. Clams are typically steamed, boiled, or eaten raw, as in ceviche, after purging to remove sand and grit by soaking in saltwater for 1 to 2 hours.^[87] This process allows the clams to expel internal sediments naturally. For safety, harvests are often closed during red tide events to prevent PSP exposure, as these biotoxins are heat-stable and unaffected by cooking.^[88] To eliminate bacterial risks like Vibrio, clams should be cooked to an internal temperature of at least 63°C (145°F).^[89]

Regional Culinary Traditions

In North America, regional clam preparations reflect coastal abundances and historical influences. The New England clam chowder, originating from the region's fishing heritage, uses quahog clams (Mercenaria mercenaria) in a creamy broth of milk or cream, potatoes, onions, and sometimes salt pork, creating a hearty winter dish that emphasizes the clams' briny depth.^[90] In contrast, the Manhattan version, developed in New York amid Italian immigrant influences, substitutes a clear, tomato-based stock without dairy, incorporating the same quahogs alongside celery and carrots for a lighter, tangier profile suited to urban eateries.^[91] On the Pacific Northwest coast, geoduck (Panopea generosa), a large burrowing clam, is often served as sashimi; the preparation involves a brief blanch in boiling water to loosen the skin, followed by chilling, cleaning, and thinly slicing the elongated siphon for a crisp, sweet texture enjoyed raw with soy sauce, wasabi, and ginger.^[92] Asian culinary traditions favor quick cooking to preserve the freshness of small, tender clams. In China, particularly Cantonese cuisine from Guangdong province, stir-fried clams in black bean sauce (chao xian) feature Manila or similar small clams wok-tossed with fermented black beans (douchi), garlic, ginger, scallions, and Shaoxing wine, yielding a glossy, umami-packed dish that highlights the clams' natural juices.^[93] Korean jogae gui, a communal grilling experience, utilizes fresh ark shells (Anadara broughtonii) and other bivalves placed directly on tabletop charcoal grills, where they open to release smoky, briny flavors enhanced by simple dips like sesame oil and chili; this method celebrates seasonal coastal harvests during summer beach gatherings.^[94] European dishes integrate clams into rice, stews, and pastas, drawing on Mediterranean seafood abundance. Spanish paella valenciana, especially coastal variants, incorporates clams such as venus clams (Venerupis spp.) into a saffron-infused rice base with shrimp, mussels, and peppers, slow-cooked in a wide pan to form a socarrat crust that absorbs the shellfish's essence.^[95] The French bouillabaisse from Provence features clams alongside rockfish, mussels, and lobster in a aromatic broth of fennel, saffron, tomatoes, and garlic, traditionally strained and served with rouille, emphasizing layered Provençal flavors from seasonal catches.^[96] In Italy, spaghetti alle vongole, a Neapolitan classic, steams littleneck clams (Ruditapes decussatus) in white wine with garlic, chili flakes, and parsley, then tosses the open shells with al dente spaghetti for a minimalist sauce that relies on the clams' liquor for silkiness.^[97] Beyond these continents, Indigenous Australian practices in the Torres Strait Islands adapt giant clams (Tridacna spp.) into stews like coconut curries, where the meat is simmered in creamy coconut milk with turmeric, garlic, and local greens, reflecting sustainable harvesting tied to monsoon seasons.^[98] In Latin America, arroz con mariscos—prevalent in Peru and Puerto Rico—blends clams with rice, squid, shrimp, and ají peppers in a one-pot dish flavored by annatto and cilantro, using local species like Protothaca staminea during peak wet seasons for optimal freshness.^[99] These variations underscore adaptations to endemic clam types and temporal availability, such as favoring smaller, sweeter specimens in summer or heartier ones in cooler months to align with ecological cycles.^[100]

Economic and Cultural Roles

Clams and their shells have played notable roles in historical economies as forms of currency and trade goods among Indigenous peoples. In North America, beads crafted from the hard shells of quahog clams (Mercenaria mercenaria) were fashioned into wampum belts and strings, serving as valuable trade items and diplomatic tools among Native American nations long before European contact; these items symbolized agreements, recorded histories, and facilitated exchanges across tribes.^[101] By the 17th century, wampum from quahog shells was adopted as a formal currency in colonial trade, officially recognized by the Massachusetts Bay Colony in 1650 due to a scarcity of European coins, though its use declined with the influx of metal currency.^[102] Beyond currency, clam shells have contributed to various non-food economic activities, including jewelry, crafts, and material production. Certain bivalve species, such as giant clams (Tridacna spp.), produce natural pearls when irritated, though this is rarer than in oysters; for instance, the South American freshwater clam Diplodon chilensis yields pearls in diverse shapes and colors, supporting small-scale artisanal pearl industries.^[103] Today, clam shells are processed into polished beads, inlays, and ornaments for global jewelry and craft markets, with demand in Asia for carvings from giant clam shells.^[104] Clams hold symbolic and religious significance in various cultures, often tied to purity, prohibition, or spirituality rather than direct worship. In the Hebrew Bible, clams and other shellfish are deemed unclean and forbidden for consumption under dietary laws outlined in Leviticus 11:9-12, which specify that only sea creatures with fins and scales are permissible, reflecting ancient Israelite distinctions between pure and impure foods.^[105] Among some Pacific Islander Indigenous groups, giant clams appear in myths and spiritual practices as embodiments of the sea's life-giving forces, with their shells used as ceremonial gongs or symbols of ancestral connections to marine environments.^[106] In modern contexts, clams feature in cultural festivals that celebrate coastal heritage through non-culinary activities like parades, crafts, and community events. The annual Yarmouth Clam Festival in Maine, held since 1965, draws over 120,000 attendees for its parade, arts and crafts fair, live music, and competitions, highlighting regional traditions and supporting local nonprofits without focusing solely on food.^[107] Such events underscore clams' enduring role in fostering community identity and economic vitality through tourism and craftsmanship.

Conservation and Threats

Harvesting and Aquaculture

Wild harvesting of clams primarily occurs in intertidal and shallow subtidal zones using manual rakes for smaller-scale operations or hydraulic dredges for commercial efforts.^[108]^[109] Hydraulic dredges, in use since the 1940s, employ water jets to loosen sediments and suction to collect clams like softshell and hard varieties while minimizing habitat disruption in soft-bottom areas.^[109]^[110] These methods target species such as the northern quahog (Mercenaria mercenaria), with fishing gear specifically designed to reduce bycatch through selective sieving and water-based extraction that spares non-target organisms.^[111]^[112] In the United States, federal quotas regulate harvests for certain clam species to ensure sustainability; for example, the annual quota for ocean quahogs (Arctica islandica), a key commercial species, stands at 5.36 million bushels, unchanged since 2004.^[113] State-level management applies to hard clams, with limits varying by region to prevent overexploitation, such as Maine's 100,000-bushel quota for mahogany quahogs.^[114] Bycatch minimization techniques include using dredges with adjustable water pressure and mesh sizes tailored to clam dimensions, which help release undersized or non-target species alive.^[111]^[112] Aquaculture production dominates global clam supply, with methods focusing on seed propagation and grow-out in controlled environments. Juvenile clams, or seed, are often reared in hatcheries and then planted using trays, mesh bags, or direct bottom spreading in intertidal or subtidal areas to protect against predators and facilitate growth.^[115]^[116] Bottom culture, where seed is broadcast onto suitable substrates like sand or mudflats, is common for species such as the Manila clam (Ruditapes philippinarum), allowing natural burrowing and filter-feeding.^[117] Tray systems, involving plastic containers filled with sediment, provide intensive nursery conditions for early juveniles before transfer to open waters.^[116]^[118] The Manila clam accounts for approximately 86% of global farmed clam production, totaling around 4 million tons annually as of recent years, with China producing over 90% of this volume and the United States contributing significant shares through Pacific Northwest operations.^[19]^[119] This species' dominance stems from its adaptability to bottom culture in coastal lagoons and its high market demand.^[120] Technological advances in clam aquaculture include selective breeding programs initiated in the 1990s to enhance disease resistance, particularly against pathogens like Quahog Parasite Unknown (QPX) in hard clams.^[121] These efforts, led by collaborations such as the Sea Grant Hard Clam Selective Breeding Collaborative, focus on developing strains with improved shell durability and survival rates through genotyping and controlled crosses.^[122] Polyculture systems integrating clams with oysters have shown promise in diluting parasite loads, as oysters act as sinks for protozoan pathogens like Perkinsus marinus, indirectly benefiting co-cultured clam health.^[123] The global clam harvesting and aquaculture industry supports substantial employment, with aquaculture overall employing over 61 million people worldwide in primary production activities, though specific figures for clams highlight thousands of jobs in key regions like China and the U.S.^[124] In Europe, harvesting remains labor-intensive, relying on hand-picking and manual dredges by groups of workers in coastal areas such as Italy's Po River delta and Spain's estuaries, where up to 1,800 fishers engage in daily collection from intertidal zones.^[125]^[126]

Environmental Impacts and Protection

Clam populations worldwide face significant threats from human activities, including overharvesting and habitat loss due to coastal development. Overharvesting has led to substantial declines in many bivalve stocks, such as a decrease in European marine bivalve production since 1998, primarily driven by intensive fishing pressures that deplete reproductive populations.^[127] Habitat destruction from urbanization and dredging further exacerbates these issues by altering essential intertidal and subtidal environments, reducing suitable areas for burrowing and feeding.^[128]^[129] Ocean acidification, resulting from increased atmospheric CO₂ absorption, has caused seawater pH to drop by approximately 0.1 units since the Industrial Revolution, hindering shell formation in larval and juvenile clams by reducing carbonate ion availability and potentially dissolving calcium carbonate structures.^[130]^[131] Pollution compounds these challenges; eutrophication from nutrient runoff promotes harmful algal blooms and subsequent hypoxia, creating low-oxygen "dead zones" that stress or kill clam populations by limiting respiration and disrupting food webs.^[132]^[133] Additionally, microplastics accumulate in clam tissues, inducing behavioral changes, oxidative stress, and potential toxicity through ingestion and bioaccumulation.^[134]^[135] Conservation efforts focus on mitigating these threats through protected areas, restocking initiatives, and international regulations. Marine protected areas (MPAs) safeguard critical habitats, with networks along the U.S. East Coast encompassing significant portions of coastal waters to restrict harvesting and promote recovery of species like hard clams.^[136] Restocking programs, particularly for giant clams in regions like the Philippines, release millions of juveniles annually to bolster depleted populations and enhance reef ecosystems, with some initiatives documenting successful integration into wild stocks.^[137]^[138] All giant clam species have been protected under Appendix II of the Convention on International Trade in Endangered Species (CITES) since 1985, regulating trade to prevent overexploitation.^[139] In October 2024, the International Union for Conservation of Nature (IUCN) reassessed giant clam species, upgrading several, including Tridacna gigas, to Critically Endangered status due to ongoing threats from overexploitation and climate change.^[140] Climate change adaptations include monitoring range shifts, as warming oceans drive some clam species, such as the American jackknife clam, to expand poleward in response to rising temperatures, necessitating updated management to track these migrations and protect shifting habitats.^[141]^[142]

References

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What is a bivalve mollusk? - NOAA's National Ocean Service
Jun 16, 2024 · Bivalve mollusks (eg, clams, oysters, mussels, scallops) have an external covering that is a two-part hinged shell that contains a soft-bodied invertebrate.
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Phylum Mollusca | manoa.hawaii.edu/ExploringOurFluidEarth
Class Bivalvia are molluscs with hinged two-part shells (Fig. 3.51 C). Examples include clams, oysters, mussels, and scallops. Class Cephalopoda are molluscs ...ʻOpihi in Hawaiʻi · Activity: Squid Dissection · Gastropod Shell Description
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Fingernail Clams - Missouri Department of Conservation
May 13, 2025 · Fingernail clams are filter feeders that remove suspended organic materials from water, so they tend to clarify the water. It also means that ...Missing: definition | Show results with:definition
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Northern Quahog | NOAA Fisheries
Clams are part of the shellfish family. Like oysters, mussels, and scallops they are bivalve mollusks, and have a hinged shell. Clams have slow growth rates and ...Missing: definition | Show results with:definition
[5]
Environmental Benefits of Shellfish Aquaculture - CT.gov
Shellfish help control harmful algal blooms, such as red tide, by removing algal cells before they accumulate to harmful levels. Improved water quality makes ...
[6]
[PDF] North Carolina Hard Clam Fishery Management Plan - NC DEQ
Aug 17, 2001 · 8.5 Ecological Benefits of Clams. Important ecological functions of clams such as fishery nursery habitat and natural water filtration have ...
[7]
How Much Is A Clam Worth To A Coastal Community?
Apr 5, 2021 · A new study estimates that oyster and clam aquaculture provides $2.8–5.8 million in services that remove excess nitrogen from the coastal waters ...
[8]
[PDF] Taxonomy, Anatomy & Biology of Bivalve Mollusks
clam-like with large hinge teeth. Order Veneroidae. Family Veneridae. Venus or “heart” clam. Side view is cardioid (heart-shaped).
[9]
The Bivalvia - University of California Museum of Paleontology
This large group includes the majority of familiar burrowing bivalves: the clams, with more than 40 families including the very large family Veneridae; the ...
[10]
Clam - Etymology, Origin & Meaning
Originating c.1500 from Scottish Middle English clam, meaning "pincers," derived from Old English clamm "grasp," clam refers to a bivalve mollusk and also ...
[11]
https://www.etymonline.com/word/clam
[12]
[PDF] Phylum Mollusca Class Bivalvia or Pelecypoda Cambrian
The phylum Mollusca includes the familiar classes Gastropoda (snails), Pelecypoda (also called Bivalvia) (clams, oysters and scallops), and Cephalopoda (squids ...Missing: taxonomic | Show results with:taxonomic
[13]
Bivalves: Phylum Mollusca, Class Bivalvia
Clams, mussels, oysters, and scallops are members to the class Bivalvia (or Pelecypodia). Bivalves have two shells, connected by a flexible ligament.
[14]
Bivalves' early evolution as revealed by mitochondrial genes
Here we present a molecular phylogeny of the class based on four mitochondrial genes (12s, 16s, cox1, cytb) and a methodological pipeline that proved to be ...
[15]
Veneridae - Wikipedia
The Veneridae or venerids, common name: Venus clams, are a very large family of minute to large, saltwater clams, marine bivalve molluscs.
[16]
Soft-shell clam - Wikipedia
Soft-shell clams (American English) or Sand gaper (British English/Europe), scientific name Mya arenaria, popularly called "steamers", "softshells", ...
[17]
Common cockle - Wikipedia
The common cockle (Cerastoderma edule) is a species of edible saltwater clam, a marine bivalve mollusc in the family Cardiidae, the cockles.
[18]
True Giant Clam | NOAA Fisheries
Jul 25, 2024 · T. gigas is typically associated with coral reefs and can be found in many habitats, including high- and low-islands, atoll lagoons, and ...Missing: distribution | Show results with:distribution
[19]
Giant clam - Wikipedia
The maxima clam has the largest geographical distribution among giant clam species; it may be found off high- or low-elevation islands, in lagoons or fringing ...Tridacna · Maxima clam · Platyceramus
[20]
Pod razor - Wikipedia
The pod razor (Ensis siliqua) is a coastal bivalve of European waters. It is edible and has been fished commercially, especially in Portugal, Spain, Ireland ...Missing: characteristics | Show results with:characteristics
[21]
Ruditapes philippinarum - Wikipedia
It has an extensive nonnative distribution, having been introduced ... Population genetics of the Manila clam (Ruditapes philippinarum) introduced in North ...
[22]
Modelling present and future global distributions of razor clams ...
Dec 20, 2016 · The tropical Indo-Pacific area contains the highest number of species (about 75–80% of all known species) [11, 17]. Despite their wide ...Methods · Modelling Of Species... · ResultsMissing: edible count
[23]
[PDF] seafood-watch-clams-global-27929.pdf
Apr 3, 2023 · There are hundreds of species of clams, cockles, and arkshells; this report will focus on the major edible species that are produced globally.
[24]
Giant clam declared critically endangered after CU Boulder ...
Oct 28, 2024 · In addition to updating the status of T. gigas, IUCN also upgraded other giant clam species, including Tridacna mbalavuana, or the tevoro clam, ...
[25]
[PDF] Carbon isotopes in mollusk shell carbonates - Union College
Jul 9, 2008 · Various mollusks construct their shells of calcite, aragonite, or both (Fig. 1a). Calcification occurs from the extrapallial fluid (EPF) ...
[26]
Sea shell diversity and rapidly evolving secretomes: insights into the ...
Jun 7, 2016 · In most molluscs, the outermost shell layer, known as the periostracum, is composed of organic components and is not calcified (but see [16]).
[27]
Ocean Quahog: Science - NOAA Fisheries
Illustration of ocean quahog clam species with dark brown, hard, oval shell showing growth. Also Known As. Clam, Quahog, Black clam, Mahogany quahog. Quick ...
[28]
Anatomy of a bivalve | Museum of Zoology - University of Cambridge
The adductor muscles contain both smooth and striated fibres, enabling sustained ('catch muscle') and rapid shell closure.Missing: strength | Show results with:strength
[29]
Part 2 - Basic bivalve biology: taxonomy, anatomy and life history
Bivalves belong to the phylum Mollusca, a group that includes such diverse animals as chitons (chain shells), gastropods, tusk shells, cephalopods (squid and ...
[30]
Blood flow in a burrowing bivalve at pedal extension and retraction
Infaunal bivalves commonly have a relatively large foot. In Donax serra (Roding) the extended foot and the shell are of approximately equal length,.
[31]
How are seashells made? - Woods Hole Oceanographic Institution
The mantle creates the shell using proteins and calcium carbonate. Proteins form a framework, and calcium carbonate fills the gaps, similar to concrete.
[32]
Cross-section of Hard Clam - Florida Museum of Natural History
Dec 20, 2023 · Clam shells form yearly growth ... These rings are formed one per year and by counting the number of rings you can determine the age of the tree.
[33]
[PDF] The Circulatory System - the NOAA Institutional Repository
The eastern oyster, in common with other spe cies of bivalves, possesses an open-type circulatory system. The systemic heart pumps hemolymph into.Missing: hemocyanin | Show results with:hemocyanin
[34]
Hemocyanin Respiratory Pigment in Bivalve Mollusks - Science
Hemocyanins, high molecular weight oxygen-binding proteins, were identified in two species of protobranch bivalve mollusks, Acila castrensis and Yoldia ...
[35]
[PDF] Hard Clam Hatchery and Nursery Production
An adult clam filters an average of 7 to 8 liters (about 2 gal- lons) per hour. Hard clams usually reach sexual maturity at a shell length (SL) of about 35 mm ...
[36]
[PDF] STUDIES ON THE COMPOSITION AND AMYLOLYTIC ACTIVITY OF ...
The crystalline style is an acellular mucoprotein rod found only in Bivalve and herbivorous gastropod molluscs. The enzymes contained within the style and the ...
[37]
Phylum Mollusca – Nervous System - BYJU'S
Bivalves – They have only 3 pairs of ganglia – cerebral, visceral and pedal, with the visceral being the largest and most essential of the three, and serving ...<|control11|><|separator|>
[38]
Peripheral sensory neurons govern development of the nervous ...
Sep 12, 2019 · During veliger stage, cerebral, pleural, and visceral ganglia form along the lateral (visceral) nerve cords in anterior-to-posterior axis. The ...
[39]
10.3: Phylum Mollusca - Biology LibreTexts
Aug 1, 2025 · Gills (ctenidia) are attached to the wall of the mantle cavity and are serviced by large blood vessels, each with its own heart. A pair of ...
[40]
Cerastoderma - an overview | ScienceDirect Topics
The majority of bivalves are gonochoric, with broadcast spawning and external fertilization. ... For example, hermaphroditic individuals in otherwise ...
[41]
The behaviour of giant clams (Bivalvia: Cardiidae: Tridacninae) - PMC
Giant clams, the largest living bivalves, live in close association with coral reefs throughout the Indo-Pacific. These iconic invertebrates perform numerous ...
[42]
Gamete plasticity in a broadcast spawning marine invertebrate - PNAS
Sep 9, 2008 · Broadcast spawning is the main mode of reproduction in the sea and involves the release of both eggs and sperm into the water column, whereupon ...
[43]
Ruditapes philippinarum - Marine Invasions research at SERC
The minimum spawning temperature is around 12°C, but the optimal range is 20-22°C, although larval development can take place at 27-30°C (Toba et al.
[44]
Interannual variability in the reproductive cycle of Manila clam ...
Partial spawning in males occurred from May to July, coinciding with seawater temperatures rising from 11.2 to 20.0 °C. In females, oogenesis commenced between ...
[45]
Lunar periodicity in reproduction of two venerid clams Meretrix ...
Dec 26, 2018 · Results showed no significant difference in growth for both clam species during each lunar phase. In contrast, significant differences were ...
[46]
The Roles of Chemical Cues in the Life Cycle of Bivalves: Spawning ...
Jan 26, 2025 · This review aims to compile the existing knowledge of the chemicals used in hatcheries to induce spawning and to improve settlement and metamorphosis in some ...
[47]
Reproductive conditioning, spawning induction and early ...
Dec 15, 2024 · The fecundity increased with the live weight of the females, showing an average value of 3.4 × 106 oocytes per female. The early development ...
[48]
Fertilization in the sea: are the hazards of broadcast spawning ...
In broadcast–spawning marine animals, rapid dilution and short lifespan of sperm following release may impose severely localized patterns of mating.
[49]
Effects of salinity on pre- and post-fertilization developmental events ...
May 26, 2023 · We concluded that in the tropical clam (Anomalocardia flexuosa) salinity plays a key role on the pre- and post-fertilization stages with best ...
[50]
[PDF] MANILA CLAM HANDBOOK - Kent & Essex IFCA
21 °C. Salinity. 24 — 31 psu. Sediment ...
[51]
[PDF] Shellfish Life Histories and; Shellfishery Models - ICES Library
species with broadcast spawning. Here the loss at low density takes the form of wastage of gametes not ferti lized. Low densities of eggs and sperm will ...
[52]
Embryonic and Early Larval Development of the Pacific Razor Clam ...
May 30, 2024 · The veliger stage ends when individuals settle out of the water column and undergo transformation into sessile juveniles.
[53]
[PDF] FAU Institutional Repository http://purl.fcla.edu/fau/fauir This paper ...
Bivalve trochophore larvae, particularly oyster trochophores, are of an appropriate size (40-60 µm) for first-feeding marine fish larvae (Hoff and Snell 1987; ...
[54]
[PDF] Softshell Clam Culture - Marine Aquaculture
The softshell clam, Mya arenaria, (Figure 1) is an ecologically important bivalve mollusk that is harvested recreationally and commercially from coastal ...Missing: definition | Show results with:definition
[55]
Embryonic and larval development of the invasive biofouler ...
Pediveligers settled by secreting byssal threads and metamorphosed to plantigrades (SL = 298.7 ± 45.2 µm) 8–10 dpf. It is noteworthy that the larvae of this ...
[56]
Byssus - an overview | ScienceDirect Topics
Byssus threads are produced in the foot of the full-grown larva (the pediveliger), and their primary function is to anchor the larva to the substrate, ...
[57]
[PDF] Spawning & Rearing Bivalve Mollusks:
Continue this routine daily until the clams reach pediveliger stage (8 to 10 days, depending on temperature. At this point, the larvae will settle to the.
[58]
Burrowing behaviour of soft-shell clams (Mya arenaria) following ...
Aug 17, 2023 · Emerson (1990) observed that smaller soft-shell clams (20–50 mm) reburrowed within minutes while larger clams (60–80 mm) took >10 h to burrow.
[59]
Mya Life History - Maryland DNR
Mya arenaria. Softshell clam. Species Description. The softshell clam is a marine/estuarine bivalve species of the Family Myidae. This species attains a ...
[60]
[PDF] Restoration and Enhancement of Softshell Clam (Mya arenaria ...
Soft shell clams reach sexual maturity within 1 ½ to 2 years. It is hoped that the stocking of clams in high densities will improve the chances of ...
[61]
Hatchery operation: culture of larvae basic methodology, feeding ...
They brood larvae until they are released into the surrounding water at 170 to 200 µm shell length (retained by a 90 µm mesh screen) in the case of Ostrea ...
[62]
Effect of stocking density on growth, settlement and survival of clam ...
However, larval survival rate (74.8–79.1%) was independent of stocking density. Results showed that a high stocking density, in the designated range, is ...
[63]
CLAMS: The RVs of the Beach - Salish Magazine
They burrow in sand, gravel, and mud at depths of around 6 to 10 inches, from the mid intertidal zone down to 60 feet.
[64]
Sediment Types with Alternation of Sandy and Rocky Shores ... - MDPI
Aug 28, 2024 · The clam sampling sites were located on the intertidal zone about 1–2 km from the tide line, being accessible at each mean spring tide. Jmse 12 ...
[65]
[PDF] Habitat Suitability Index Models: Hard Clam. - DTIC
The optimal salinity range for hard clams throughout their range is assumed to be 22 to 35 ppt. Water temperature (V3) requirements for all life stages are ...
[66]
[PDF] The Role of Water Temperature in Hard Clam Aquaculture1
The freezing point of seawater varies with salinity; seawater at 35 ppt freezes at 28.6°F. (-1.9°C), while brackish water freezes at higher temperatures and ...Missing: preferred | Show results with:preferred
[67]
Inventory of New Jersey's Estuarine Shellfish Resources (Hard Clam ...
Sep 19, 2024 · Adults have an optimal temperature range of about 20-30°C (68-86°F) ... Hard clams prefer a salinity range of 20-35 ppt, with mortality ...
[68]
[PDF] Status Review Report of Seven Giant Clam Species - NOAA Fisheries
Giant clams are a small but conspicuous group of the planet's largest and fastest growing marine bivalves. Of the seven candidate species, T. squamosa has the ...
[69]
a decadal monitoring effort of endangered giant clams by citizen ...
Sep 30, 2024 · They are found throughout the Indo-Pacific region, but the highest species diversity lies in the Central Indo-Pacific (Tan, Neo & Huang, 2022a).
[70]
Mercenaria mercenaria - Marine Invasions research at SERC
Mercenaria mercenaria X campechiensis hybrids comprised about 13-18% of clams collected in Charlotte Harbor (Arnold et al. 2009). Mercenaria mercenaria X ...
[71]
Mercenaria mercenaria (northern quahog) - Animal Diversity Web
When the water temperatures approach 23°C (73°F), and other environmental cues such as pH change, spawning commences(Britannica 2000, Stewart 1996). Some ...
[72]
Common cockle (Cerastoderma edule) - MarLIN
The familiar edible cockle. The shell is solid, thick, equivalve, globular and broadly oval in outline; up to 5 cm long but usually less.
[73]
Phylogeny and origins of chemosynthetic vesicomyid clams
The diverse gigas-group also exhibited the greatest variability: minimum depths range from sublittoral to abyssal and maximum depths range from upper bathyal to ...
[74]
Taxonomy and palaeoecology of two Late Pleistocene species of ...
Apr 4, 2017 · This gives the species a known depth range between 1,197 and 2,054 m, which is a moderately deep range for the genus according to Krylova ...
[75]
Bivalvia - Wikipedia
The name "bivalve" is derived from the Latin bis, meaning 'two', and valvae, meaning 'leaves of a door' ("leaf" is an older word for the main, movable part of ...
[76]
[PDF] Calyptogena diagonalis, a New Vesicomyid Bivalve from ... - MBARI
Type locality: Cold seeps along the Costa Rica subduc- tion zone (9°42.28"N, 86°4.38"W) from 2980 to 3800 m depth. C. diagonalis occurs in clusters of 10 to ...
[77]
[PDF] BIVALVES
Bivalves also require extended siphons to be able to extend them out of the burrow. Again, the greater the siphon length, the deeper the burrow. This evident in ...
[78]
Environmental Benefits - Florida Shellfish Aquaculture Online ...
A single littleneck-sized clam can filter 4.5 gallons of seawater per day. As clams feed, they create currents that move water in and out of the animal. Tiny ...
[79]
Gifts from the sea: shellfish as an ecosystem service
Dec 11, 2014 · Bivalves like clams and oysters are prodigious filter-feeders; some species might filter as much as 55 gallons of seawater in a day. This ...
[80]
Bioturbation in a Declining Oxygen Environment, in situ ...
Bioturbation, the displacement and mixing of sediment particles by fauna or flora, facilitates life supporting processes by increasing the quality of marine ...
[81]
Bivalve Predators and their Control - Wiley Online Library
Major bivalve predators include birds, fish, crabs, starfish, sea urchins, molluscs, and flatworms. Eider ducks and oystercatchers are important avian ...
[82]
Quahog Clam Animal Facts - Mercenaria mercenaria - A-Z Animals
These clams have a variety of predators like fish, crabs, infauna, and birds. Fish predators include angelfish, wrasses, and triggerfish. Crab predators include ...
[83]
[PDF] Sodium channel mutation leading to saxitoxin resistance in clams ...
A sodium channel mutation in clams, caused by a single amino acid change, increases saxitoxin resistance, and thus increases the risk of PSP.
[84]
Giant Clam Physiology - Eric J. Armstrong
Giant clams also host symbiotic algae (genus Symbiodinium) from which they obtain a significant portion of their daily energy needs.
[85]
[PDF] Ten years of Tridacna sclerochemistry at up to daily resolution from ...
May 17, 2025 · Giant clams such as Tridacna sp., with their rapid shell accretion (mm-cm/year), decade-long lifespans and aragonitic shells, are invaluable ...
[86]
Clams as pollution bioindicators in Kuwait's marine environment
Field experiments indicated statistically significant increases in Hg and Cu concentrations in the transplanted clams at most stations, no change in Cd ...Missing: indicator species acidification
[87]
An Assessment of Heavy Metals Toxicity in Asian Clam, Corbicula ...
Jul 15, 2019 · Overall, Asian clam from Pa Sak River was found to contain high concentrations of Zn, Cu, Cd, Cr, and Pb compared to Mekong and Lopburi River. 1 ...
[88]
Jeopardy at Sea: What Atoms in Clams Tell us about Ocean ...
Nov 27, 2018 · This reveals that ocean acidification not only poses a risk to the clams themselves, but also to the people who eat them; cobalt is a heavy ...Missing: indicator | Show results with:indicator
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The Archaeological Study of Shell Middens - ThoughtCo
May 30, 2019 · Shell middens are ancient heaps of shells found worldwide, often remnants of prehistoric meals. Archaeologists study shell middens to learn ...
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Clams, steamed or boiled - Nutrition Value
Clams, steamed or boiled contains 16 calories per 15 g serving. This serving contains 0.2 g of fat, 2.8 g of protein and 0.7 g of carbohydrate.
[91]
[PDF] Nutritional Value and Food Safety of Bivalve Molluscan Shellfish
Jan 5, 2022 · For example, molluscan shellfish can be an excellent source of vitamin B12, choline, selenium, iron, and zinc, Furthermore, the proportion of ...<|separator|>
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How To Clean Clams - The Best Way to Purge Sand
Rating 4.7 (49) · 1 hr 15 minMar 1, 2011 · Let the clams purge their sand and grit with 1 hour of soaking. To finish cleaning, the shells of clams need scrubbing with a brush under cold ...Clam Recipes To Try · How To Clean Clams -- The... · To Purge Sand From Clams
[93]
Shellfish Safety - Skagit County
... internal temperature must reach 145°F for 15 seconds. Thorough cooking destroys vibrio bacteria (note: cooking doesn't destroy biotoxins, aka "red tide").
[94]
[PDF] Recreational Shellfish Harvesting: Safe handling, storing, and cooking
Cooking Shellfish To ensure proper food safety, shellfish must be cooked to an internal temperature of at least 145°F.
[95]
Chowders: The hearty soup for cool fall temperatures - Escoffier
Oct 11, 2018 · The classic New England–style clam chowder is made from chopped quahog clams, tender potatoes and onions that are stewed in a heavy cream base.
[96]
The Minimalist; What's the Best Clam Chowder? One Made With the ...
Oct 29, 1997 · -- New England Clam Chowder: add 1/2 cup or more of milk, cream or half-and-half along with the chopped clams. -- Manhattan Clam Chowder ...
[97]
Geoduck, Sashimi and Sautéed Recipe - Serious Eats
Rating 5.0 (1) · 15 minPlace geoduck inside pot and boil briefly until skin of the trunk turns a shade darker, about 20 seconds. Using tongs, place the geoduck in ice water to stop ...
[98]
Stir-Fried Clams in Black Bean Sauce - The Woks of Life
Rating 5.0 (10) · 25 minJan 3, 2022 · Chinese Stir-fried fresh clams in black bean sauce with garlic, ginger, scallion and cilantro is a classic fermented black bean dish that is ...
[99]
My Fiery Love Affair with Korean Jogae Gui (Shellfish BBQ)
Nov 10, 2005 · Jogae Gui is a Korean shellfish BBQ where live shellfish are grilled at the table, with the risk of burns from the hot juice.
[100]
Authentic Spanish Seafood Paella Recipe - Spain on a Fork
Rating 5.0 (23) · 45 minThis Authentic Spanish Seafood Paella Recipe is loaded with spanish flavors, and believe it or not, it is very easy to make.
[101]
Real Bouillabaisse (Bouillabaisse Marseillaise) Recipe - Serious Eats
Rating 4.0 (2) · 3 hr 20 minThe ingredients used for bouillabaisse: mixed fish, fennel, onion, garlic, tomato.
[102]
Spaghetti Alle Vongole in Bianco (Spaghetti With White Clam Sauce)
Rating 3.7 (3) · 1 hr 30 minSpaghetti alle vongole, an Italian classic, is a light pasta infused with garlic, briny clams, white wine, and chile flakes.
[103]
Nornie Bero's Masig clam and coconut curry recipe Recipe | SBS Food
25 minJul 1, 2025 · Described as having a sweet flavour similar to scallops, the giant clam meat is delicious in a coconut curry sauce.
[104]
Arroz Con Mariscos (Puerto Rican Seafood Rice) - Salima's Kitchen
1 hrDec 19, 2024 · This Puerto Rican style seafood rice (Arroz con Mariscos) is a fabulously delicious, less complicated version of Spanish Paella.
[105]
6 Best Clam Dishes in South America - TasteAtlas
Oct 16, 2025 · Almejas al matico is a traditional dish originating from Chile. The dish is usually made with a combination of clams, matico leaves, lemon juice ...
[106]
Wampum - Ganondagan
Contrary to misconceptions, wampum was not "indian money." Wampum clearly had value as a trade item between the various Native peoples before European contact.
[107]
From Beads to Bounty: How Wampum Became America's First ...
Jan 14, 2013 · Wampum was officially recognized as a currency by Massachusetts Bay Colony on October 18, 1650, and rates of exchange were formalized.
[108]
Dentalium - CLARKE HISTORICAL MUSEUM
Mar 2, 2018 · Dentalium, a small ocean mollusk native to the areas around Vancouver Island, was used as a form of currency by tribes throughout the Pacific ...Missing: potlatch | Show results with:potlatch
[109]
Shape, Microstructure, and Chemical Composition of Pearls from the ...
Jul 7, 2023 · Diplodon chilensis can produce pearls in a variety of shapes, sizes, and colors. Pearl production in this species is not a rare phenomenon since ...<|separator|>
[110]
The Purple Dye That Powered the Ancient Phoenician Empire
Jun 11, 2025 · Murex purple was superseded by synthetic dyes in the 19th century, but it took years to replicate its most appealing features, like staying fast ...
[111]
Polished Shell Beads - Accio
Rating 5.0 (78) · Free 14-day returnsThe global market for polished shell beads is valued at approximately $1.2 billion, with projections indicating a 6.8% CAGR through 2028. This growth is ...<|separator|>
[112]
https://www.fisheries.noaa.gov/species/atlantic-surfclam/resources
[113]
https://www.fisheries.noaa.gov/bulletin/final-2025-atlantic-surfclam-and-ocean-quahog-specifications
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The History, Myth, and Future of the Giant Clam - Atlas Obscura
Jul 6, 2021 · Pacific islanders put giant clams to practical use while also seeing in them a certain spirit. The shells served on some islands as ceremonial ...
[115]
Yarmouth Clam Festival - A Maine Summertime Tradition Since 1965.
The Yarmouth Clam Festival, started in 1965, is Maine's largest free festival, supporting local nonprofits, and is funded by sponsorships and fees.Schedule · Food · Events · Festival InformationMissing: cultural culinary
[116]
Fishing and farming methods | Seafood basics
After an appropriate growth period, the shellfish are harvested by hand, rakes or dredging. Seaweed may also be grown by bottom culture. Off-bottom culture ...
[117]
[PDF] A Review of the Potential Impacts of Mechanical Harvesting on ...
Jan 12, 1995 · A hydraulic clam dredge is a shellfish harvesting device that has been utilized since the 1940s for the harvesting of soft clams, (Mya), hard ...Missing: bycatch minimization
[118]
[PDF] A review of the fishing gear utilized within the Southeast Region and ...
Hydraulic escalator dredges have been utilized since the 1940s to harvest shellfish such as clams and oysters and are designed expressly for efficient ...
[119]
Ocean Quahog | NOAA Fisheries
Fishing gear used to harvest quahogs is designed to minimize bycatch. ... Commercial fishermen harvest ocean quahogs with hydraulic clam dredges, which use ...
[120]
Atlantic Surfclam: Resources - NOAA Fisheries
Fishing gear used to harvest surfclams is designed to minimize bycatch. ... Surfclams are the most important commercial clam species harvested in the ...
[121]
Final 2025 Atlantic Surfclam and Ocean Quahog Specifications
Oct 31, 2024 · The final quotas, which have remained unchanged since 2004, are: Atlantic surfclams: 3.4 million bushels. Ocean quahogs: 5.36 million bushels.Missing: per | Show results with:per
[122]
Ocean Quahog: Commercial Fishing - NOAA Fisheries
The annual quota for harvest of mahogany quahogs from within the Maine mahogany quahog zone is 100,000 Maine bushels (1 Maine bushel = 1.2445 ft3). This ...
[123]
Clams - Aquatic Network
Off-Bottom Culture: Clams are placed in mesh bags or trays secured to the seabed. This method offers protection from predators and allows for easier monitoring ...
[124]
[PDF] Nursery Growout Methods for Aquacultured Shellfish
Some clam culturists in Virginia use sand trays - open top plastic boxes with 3 to 4 inches of sand - to grow 4 to 6 mm clam seed. After adding the seed, the ...
[125]
[PDF] Clam Aquaculture
Clam aquaculture involves raising clams from larvae, using hatcheries, and growing them in nursery methods like upwellers, field boxes, or netted runs.
[126]
[PDF] Small-Scale-Clam-Farming.pdf - Washington Sea Grant
Intertidal trays or bags may be more financially feasible nursery systems. Nestier trays are two-foot by two-foot trays with ¼-inch diameter openings that ...
[127]
Population genetics of the Manila clam (Ruditapes philippinarum) in ...
Dec 14, 2020 · Second, the annual production of Chinese Manila clams is about 3 million tons, accounting for > 90% of the world' production. This species ...Missing: global | Show results with:global
[128]
Assessment of the environmental efficiency of Manila clam ...
Jan 30, 2025 · The Manila clam (Ruditapes philippinarum, Adam & Reeve 1850), whose total production accounted for 4 million tons and € 6.7 billion in 2019 (FAO ...
[129]
[PDF] Sea Grant Hard Clam Selective Breeding Collaborative
Hard clam producers in the Northeast have periodically experienced high mortality since the 1990's due to QPX, a disease that affects hard clam growth and ...<|separator|>
[130]
Research (News - The Hard Clam Selective ... - NY Sea Grant | NYSG
May 2, 2022 · Traditional selective breeding has had some success producing clams with more durable shells and disease resistance. Allam's team has ...
[131]
Intensive oyster aquaculture can reduce disease impacts on ...
marinus infection and their lifespan once infected, reduces disease by diluting parasites in the environment. Our modeling results offer new insights toward the ...Missing: polyculture clams
[132]
FAO Report: Global fisheries and aquaculture production reaches a ...
Jun 7, 2024 · Global fisheries and aquaculture production in 2022 surged to 223.2 million tonnes, a 4.4 percent increase from the year 2020.
[133]
On Italy's Po River, Europe's biggest clam harvesting production ...
Mar 5, 2023 · 1,800 fishers harvest clams from lagoon. The Sacca is a UNESCO World Heritage site and home to Europe's biggest clam harvesting production.
[134]
As Spain's 'peasant farmers of the sea,' groups of women dig for clams
Jun 2, 2023 · Clam diggers gather in the lower estuary of Lourizan, before starting their work day in Galicia, northern Spain, Thursday, April 20, 2023.
[135]
Global Production of Marine Bivalves. Trends and Challenges
Nov 27, 2018 · In Europe, responsible for 5.5% of the world production of marine bivalves, the production has decreased since 1998. This decrease is mainly due ...2.2 Global Trends · 2.4 Europe · 2.5 Stock AssessmentMissing: overharvesting | Show results with:overharvesting
[136]
Giant clams, iconic and imperiled, may get U.S. endangered species ...
Jul 26, 2024 · In its proposal this week, NOAA highlights several threats to giant clams, including habitat destruction, overharvesting, disease, and climate ...Missing: loss | Show results with:loss
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The Underwater World of Giant Clams | The Pew Charitable Trusts
Jun 7, 2021 · Giant clams face many threats. The suite of challenges facing these creatures include overfishing, habitat degradation and destruction, ...Missing: loss | Show results with:loss
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Ocean acidification | National Oceanic and Atmospheric Administration
Sep 25, 2025 · Impacts of ocean acidification on shell builders If the pH gets too low, shells and skeletons can even begin to dissolve. The pteropod, or "sea ...
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[PDF] Ocean Acidification and Shellfish - US EPA
acidity.16 Under the Reference scenario, ocean acidification is projected to cause pH to drop an additional 0.3, representing a 100% increase in acidity ...
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Coastal Eutrophication and the Productivity of Clams and Oysters
... clam growth, and avoiding excessive eutrophication that can lead to destructive phenomena, such as harmful algal blooms and periods of anoxia or hypoxia.
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Possible consequences of eutrophication - Coastal Wiki
Jul 20, 2025 · 2.1 Increased biomass of phytoplankton resulting in algal blooms · 2.2 Dissolved oxygen depletion or hypoxia · 2.3 Dead zones · 2.4 Eutrophication- ...
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Microplastics and seafood: lower trophic organisms at highest risk of ...
Mar 1, 2020 · Behavioural changes are observed in clams; 20 μm polystyrene microplastics also induced effects on antioxidant capacity, DNA damage ...
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Occurrence of Microplastics in Commercial Seafood under the ...
The exposure to plastic debris may cause in marine organisms physical and mechanical damage, inflammation, obstruction of the gastrointestinal tract (GI), and ...
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[PDF] Atlantic Clam (US) - Seafood Watch
Mar 4, 2024 · This report contains recommendations on two wild-caught clam species: northern quahog (hard clam). (Mercenaria mercenaria) and softshell clam ( ...
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Giant Clam Restocking Project Boosts Bohol's Marine Biodiversity
Aug 23, 2024 · Since its inception in 2013, the giant clams restocking project has aimed to revitalize Bohol's degraded marine ecosystems. Initially, 20 giant ...
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Achievements and lessons learned in restocking giant clams in the ...
Marine protected areas were also identified as suitable sites for restocking giant clams. Overall, the giant clam restocking programme in the Philippines has ...
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Proposed Listing Determinations for Ten Species of Giant Clams ...
Jul 25, 2024 · All species of giant clams have been listed under appendix II of CITES since 1985, and we can therefore rely to some extent on trade ...
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Predicting the future distribution of a commercially important clam ...
Aug 15, 2025 · In 2020, Ruditapes philippinarum accounted for 24 % of global mollusc aquaculture production with a harvest of over 4 million tonnes (FAO, 2022) ...
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Climate Change Drives Poleward Increases and Equatorward ...
Apr 20, 2020 · It has therefore been predicted that warming seas should also drive increases in the abundance of species at their poleward range side [6].