Scallops: Characteristics, Species, Food, Shells | Sea Life, Islands and Oceania

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SCALLOPS

lion's paw scallop

Scallop is the a common name for various species of marine bivalve mollusks in the taxonomic family Pectinidae. The name "scallop" is also sometimes applied to species in other closely related families within the superfamily Pectinoidea, which also includes the thorny oysters. [Source: Wikipedia]

Like clams, oysters and mussels, scallops are bivalve mollusks. They have a fan-shaped shell composed of two hinged halves, generally with rows of ridges or radiating ribs along on the shell. One of the main differences between scallops and other kinds of shellfish such as clams and oysters is their ability to swim. Using its adductor muscle to open and close their shells in rapid succession, they can propel themselves forward in a zigzag direction. This helps them escape predators, such as sea stars, that other bivalves like mussels, clams, and oysters can’t avoid. Despite mobility, scallops tend to stay in one place and are often found attached to something. [Source: Heather Hall, AZ Animals, December 27, 2022]

Scallops can be found living in shallow water habitats all around the world and some deep water ones too. You can find them in tropical, temperate, cold and polar seas, but most species live in warmer waters. The exteriors of scallop shells are typically brown, white, or pink. Scallops usually range in size from five to 12.5 centimeters (two to five inches) in width.

The scallop shell is one of the most recognizable of all shells. Sometimes scallops make pearls and shells themselves are sometimes used in jewelry. Scallop pearls also lack the iridescent shine of oyster pearls. Scallop pearl are very rare It is estimated that only 1-in-10,000 scallops produce pearls.

Websites and Resources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se ; Encyclopedia of Life eol.org ; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems

Scallops as Food

Many species of scallops are prized as a food sources, Generally, the scallop's shells are removed and the soft adductor muscles are consumed. .In Japan scallop sushi is called “hotategai”. Sushi made with farmed scallops is one of the most eco-friendly types of sushi. Good fresh hotategai can be expensive.

In Galician cuisine, scallops are baked with breadcrumbs, ham, and onions. Dried scallop is known in Cantonese Chinese cuisine as conpoy . Smoked scallops are sometimes served as appetizers or used as an ingredient in the preparation of various dishes and appetizers. Taiwanese steamed scallops are a real treat. [Source: Wikipedia]

Top Food Scallops, Globally
Seafood Ranking — Common name — Scientific name — Wild or Farmed — Harvest in tonnes (1000 kilograms)
67) Yesso scallop — Patinopecten yessoensis — Wild — 318,081 tonnes
79) American sea scallop — Placopecten magellanicus — Wild — 267,745 tonnes

Scallops as Symbols

Symbols of the Santiago de Compostela pilgrimage

Aphrodite emerged from a scallop shell. The scallop shell was also used by the Crusaders in the Middle Ages as a symbol Christianity. Today it associated most with St. James and the pilgrimage to Santiago de Compostela. St. James was one of Christ's 12 apostles. According to legend he sailed to Spain to preach the Gospel and then returned to Jerusalem, where he was beheaded in 44 AD. for preaching. Because St. James was the first apostle to be martyred after Christ's crucifixion, many consider him the most senior and most important of all the martyred disciple-saints of the Roman Catholic Church. He is believed to be buried in Santiago de Compostela, Spain

Since the early Middle Ages, millions of pilgrims from all Europe, have converged on Santiago de Compostela to pay their respect to St. James. They have traveled on foot, on horseback, in carriages and in donkey carts. Today, around 100,000 pilgrims and tourist each year follow the same route on foot, on horseback, with donkeys and on bicycles.

Pilgrims are often identified by a talisman or badge bearing a scallop shell, the coquille St. Jacque, or symbol of Saint James. No one is sure why the scallop shell was chose as the symbol for St. James and his pilgrims. Many pilgrims claim the shell was first used by Charlemagne's armies but scholar it may have originated with a pre-Christian Venus cult of sexual gymnast who used to hold orgies at Stonehedge-like standing stone temples.

In the 9th century, according to one story, Charlemagne had a dream shortly before he died in which he saw a star-lit road leading from France and Spain to the as yet undiscovered tomb of St. James. In the dream, God told Charlemagne it was duty to lead his army across the Pyrenees to free northern Spain from Moorish-Muslim rule. Carrying banners with the scallop shell symbol, Charlemagne's armies marched to Spain threw the Muslims out of Castile and León, Galicia. Navarre and La Rioja. This assertion isn't backed up by any historical evidence.

Scallop Shells Sought by Collectors

There are more than 350 species of scallops. Scallop shells found on beaches and sought after by seashell collectors include the orange lion’s paw, Irish deep, purple pectin, yellow pectin, pallium pectin, bay scallop, great scallop, queen scallop variegated scallop, noble scallop and Mediterranean scallop

The king scallop (Pecten maximus) is a large, impressive Atlantic species, which is said to have been the model for the Shell oil company logo. King scallops are distinguished from all other scallops by their large size and symmetrical 'wings'. Their "ears" are prominent and are a minimum of half the width of the shell. The color of the body of a king scallop shell is pink or red with the mantle marbled brown and white. [Source: Nicholas Argent, Citrus Reef]

The lion’s paw scallop (Nodipecten nodosus) is native to the Atlantic coast of North, Central, and South America. Measuring between 6.4 – 15.2 centimeters (2.5-6 inches long), it is prized by shell collectors for its bright colors, distinctive features, and large size. The shell is bright orange or red in color and features broad ridges and a knobby surface that is said to resemble the paw of a lion. They lives on rocks and prefers shaded areas or caves between nine and 49 meters (30 and 160 feet) deep. These shells are rarely wash up on beaches. Collectors are mostly supplied with shells caught by commercial fishermen. In some places, including waters off some parts of Brazil, overfishing has resulted in the lion’s paw scallop becoming rare and in danger of local extinction. [Source: Daniel Stokes, Dutch Shark Society, April 6, 2022]

Scallop Characteristics

Scallop organs and body parts

Scallops are bivalves (having two shells), like clams and oysters. The shells are held together by the adductor muscle (the part of the scallop people typically eat). Sea scallops can live up to 20 years. They grow quickly for the first few years of their life.

Scallops are cold blooded (ectothermic, use heat from the environment and adapt their behavior to regulate body temperature), heterothermic (have a body temperature that fluctuates with the surrounding environment) and have bilateral symmetry (both sides of the animal are the same). Sexual Dimorphism (differences between males and females) is not so apparent: Both sexes are roughly equal in size and look similar. [Source: Alexandra Sarabia and Catherine Zymaris, Animal Diversity Web (ADW) /=]

Scallop shells vary in colors and patterns of pigmentation, which can be affected by both environmental and genetic factors. Their shells also primarily made of calcite, making them relatively insusceptible to dissolution and recrystallization. In general, scallops lack siphons and the anterior adductor muscle. A large and well-developed posterior adductor muscle is used for locomotion. Young individuals often attach to surfaces by byssal threads (silky filaments). Numerous light receptors (eyes) also line the edge of the mantle. /=\

Deep sea scallops respond to sight and touch. The scallops' eyes are very developed with corneas and lenses, According to Animal Diversity Web: Even though deep sea scallops have a high concentration of sensory organs near the edge of the mantle cavity, they only have a relatively simple nervous system. Visceral ganglia near the optic lobes fuse with other ganglia to form a simplistic "visceral brain", which constitutes most of the scallop's nervous system. The concentration of sensory organs allow the scallop to be aware of its surroundings at all times. Most prominent and useful are their row of eyes between the two vavles, which aid in watching for predators. The eyes are usually coblat blue in color and are located on the tip of pallial tentacles. Although their eyes are complete with cornea and lens, they are unable to discern shapes. They can only detect changes in light and movement and react to flashing lights or stripes that move at particular speeds, which resemble speeds of their predators, starfish and whelks. The chemical sensitive pallial tentacles are also able to react to excretions of starfish. When a predator is spotted or the scallop is touched, the scallop quickly propels itself from danger. They can do this by rapidly clapping their two valves together and moving in jerks or darts. Movement occurs through a type of jet propulsion. A jet of water is forced backwards and out through the wings and hinge. The locomotion is mainly powered by the large muscle (See Below). [Source: Kathryn Hodges, Animal Diversity Web (ADW) /=]

Scallop Behavior, Feeding and Predators

Scallops are filter feeders. It was was once thought that some species only consumed phytoplankton but recent research indicates zooplankton is also an important source of nutrients. Zooplankton species that Queen’s scallop consumes include halacarid mites, calanoid copepods, halacarid fragments, copepod fragments, crustacean nauplii, barnacle cyprids, and cladocerans. [Source: Alexandra Sarabia and Catherine Zymaris, Animal Diversity Web]]

According to Animal Diversity Web: The deep sea scallop's ctenidia and labial cilia serve as instruments for food collection. There is a ventral and dorsal siphon. Water enters the ventral siphon and a current is maintained to pass through the gill lamellae. Here, the scallop separates food particles from mud and sand according to size. The ctnedia then transport the food particles to the mantle cavity and circulate over many groups of cilia. The particles become covered with mucus and are pushed either toward the mouth or the rejection path, which leaves through the dorsal siphon. The mucus covered food is then carried to the stomach through the esophagus, but first passes through the crystalline style, a gelantinous rotating rod. Here, the food is digested in intracellular food vacoules and waste is removed through the intestines and out through the anus. [Source: Kathryn Hodges, Animal Diversity Web]

Scallops are both sessile (fixed in one place) and motile (move around as opposed to being stationary). They sense and communicate using touch, vibrations and chemicals usually detected by smell. Queen’s scallops grow on maerl (purple-pink hard seaweed) and possibly communicates with it through active molecules gamma aminobutyric acid or other surface properties of the maerl. Responses to stress from potential predation or changes in environment are innate. Because Queen’s scallop senses danger through disturbance, it detects when fish trawls are approaching. /=\

Scallop are preyed on upon primarily by marine bottom-dwellers, such as common starfish. hermit crabs and brown crabs as well bottom-dwelling fish. Their main anti-predator adaptations are camouflage, hiding beneath sand and mud and jet propulsion escapes

Scallop Jet Propulsion and Movement

Scallops are the most mobile bivalves and one of the few groups of outwardly-shelled mollusks that can actually swim. They swim and move around using water-jet propulsion created by many rapid valve movements that expel water from the mantle cavity. When scallop senses danger or any other kind of disturbance, its swimming escape reflex is triggered. [Source: Alexandra Sarabia and Catherine Zymaris, Animal Diversity Web (ADW) /=]

By closing their the two halves of their shells together they expel a jet of water that propels them backward or skyward. By repeatedly opening and shutting their shells they sort of wobble and dance through the water. Scallops often employ their propulsion system to escape from slow-moving starfish that prey up on them. Movement also provides them with the opportunity to move to a new environment if conditions in the old one become unfavorable.

Adam Summers, a professor of bioengineering at the University of California at Irvine, wrote in Natural History magazine, “The jetting mechanism in a scallop works like a somewhat inefficient two-stroke cycle engines. When the adductor muscle closes the shell, water squirts out; when the adductor relaxes, the rubbery pad pops the she’ll back open, allowing water back inside and replenishing the jet. The cycles repeat until the scallop is out of predator range or closer to a better food supply. Unfortunately, the jet-power phase is delivered for only a short part of the cycle. Scallops, however, have adapted to make the most of what power and thrust they can produce.”

One of the scallops tricks to increase speed is to lighten their load by having tiny shells, whose weakness is offset by corrugations. “Another adaptation — the key, in fact, to their culinary charm — is the large, tasty adductor muscle, physiologically suited to the powerful cycles of contraction and relaxation in jetting. Finally, that little rubbery pad is made of a natural elastic which does an excellent job or returning the energy put into the shell closure.”

Scallop Mating and Reproduction

Scallops spawn externally, with released sperm fertilizing released eggs. They are polygynandrous (promiscuous), with both males and females having multiple partners and are also simultaneous hermaphrodites in which individuals have sex organs of both sexes and can produce both sperm and eggs even in the same breeding season.

Deep sea scallop males and females reach sexual maturity by two years of age. Their breeding season is late summer and early fall, but can also occur in spring within populations in the Mid-Atlantic region Queen’s scallop breeds in the spring and summer. On average males and females reach sexual maturity at age one year. There is no parental protection, however, there is pre-fertilization provisioning and eggs provide yolk to sustain the lecithotrophic larvae. [Source: Alexandra Sarabia and Catherine Zymaris, Animal Diversity Web (ADW) /=]

Instead of releasing eggs and sperm randomly, scallops stimulate one another to spawn at the same time. The sperm is released first and then enters the food current of other scallops, which causes them to release eggs into the mantle cavity. According to Animal Diversity Web: When spawning takes place, sperm are normally released into the environment initially. Fertilization occurs when the eggs are subsequently released and come into contact with the sperm. The release of gametes into the surrounding water usually occurs in the warmer months of spring and summer, but the actual time varies depending on the region and from year to year. /=\

The majority of deep sea scallops undergo multiple sex changes during their lifetime. They are known as functionally ambisexual and shelter the ova and sperm in the same gonad, but the two are produced in different areas of the gonad. About four percent are hermaphrodites and carry both an ovary and testis within the mantle cavity. The ovary is a very bright pink when carrying ripe eggs and the cream colored testis lie behind the ovary. The two are fused together and have short ducts with no glands. Eggs are not released in the water, but wait for the sperm in the mantle cavity. Fertilization occurs when the sperm usually meet the eggs near the opening of the mantle cavity. Then, the scallops immediately release the zygotes into the water. [Source: Kathryn Hodges, Animal Diversity Web (ADW) /=]

Scallop Development

According to Animal Diversity Web:Queen’s scallop development is influenced by both environmental and inherited factors. Additionally, their life cycle includes the trochophore and veliger larval stages. Generally, development can be described by three phases based on the nature of the energy source and the nature of the locomotion used. The first phase is considered lecithotrophic, a phase in which nutritional requirements for larvae do not extend beyond what is provided within the egg. Lecithotrophic species also have a reduced larval period during which no specific food is consumed. The second and third phases are considered planktotrophic, a phase in which larvae ingest plankton suspended in the water column. [Source: Alexandra Sarabia and Catherine Zymaris, Animal Diversity Web (ADW) /=]

Evolution of the Shell Oil symbol

The first phase, or embryonic phase, is extremely vulnerable to environmental conditions and requires locomotion to ensure that the early larvae move into the water column. After fertilization occurs, the offspring remain on or near the seabed for a couple of days until developing into trochophore larvae. In the second phase, or dispersal phase, the trocohophore larvae rise to the surface of the water and is transported by water currents into the water column. Eventually, the trochophore larvae become veliger larvae. The third phase occurs when veliger larvae find a suitable substrate to settle on to undergo metamorphosis and juvenile life before becoming adults. /=\

Queen’s Scallop

Queen’s scallops (Scientific name: Chlamys opercularis) are commercially known as “queens” or “queenies”. Native to the North Atlantic Ocean and Mediterranean and Adriatic Sea, these mollusks range from northern Norway and the Faroe Islands in the north, to the Iberian Peninsula in the south and can be found off western Ireland and the Isle of Man. They have a lifespan of 8 to 10 years and grow the most in late autumn and early winter. [Source: Alexandra Sarabia and Catherine Zymaris, Animal Diversity Web (ADW) /=]

Queen’s scallop is distinctly left convex (the left valve is more rounded than the right valve). The shells vary in colors and patterns of pigmentation, They can grow up to nine centimeters (3.5 inches) millimeters in shell height. Queen’s scallop are primarily found on firm, sandy gravel or mud in the sea bottom at depths of more than 100 meters in places where the water temperature are relatively cool. They are often found attached to various kinds of algae, Bryozoa, hydroids, clean shells and general benthic (bottom-dwelling) epifauna. Studies have indicated that maerl grounds (areas formed from loose-lying coralline red algae and characterized by high tides and water movements) support large numbers of Queen’s scallop and are believed to act as nursery areas for larvae.

Queen’s scallop have not been evaluated for the International Union for Conservation of Nature (IUCN) Red List. They have no special status according to the Convention on the International Trade in Endangered Species (CITES). They are widely consumed as human food and have a high commercial fishing value. According to Animal Diversity Web (ADW) There is a large European market, especially in the United Kingdom and Spain, for fresh Queen’s scallop. The Queen’s scallop industry provides an important food source that can be exported for profit and creates many jobs. Fisheries and governments are trying to push the industry towards sustainable aquaculture, which could be less destructive to the natural ecosystem, less harmful in discarding undersized scallops, and more environmentally friendly. A more sustainable system could also be more economically viable and ensure a more consistent yield of product. [Source: Alexandra Sarabia and Catherine Zymaris, Animal Diversity Web (ADW) /=]

Deep Sea Scallops

Deep sea scallops (Scientific name:Placopecten magellanicus) are native to the northern Atlanic Ocean and range from Labrador in Canada to North Carolina. They are also found in other areas as a result of farmers introducing them to new aquaculture ventures in other locations. Deep sea scallops reach full adulthood at four years of age, Their lifespan in the wild is typically six to eight years. [Source: Kathryn Hodges, Animal Diversity Web (ADW) /=]

Deep sea scallops are typically found at depths of 20 to 200 meters (66 to 656 feet) at an average depth of 40 meters (131 feet). They can only survive temperate, saltwater and marine environments and are found in coastal areas and in the open ocean. They prefer the cool water of the Northern Atlantic, where water temperature s rarely rise above 20̊C (68̊F) and spend most of their time lying on the sand or mud of the ocean bottom. Populations north of Cape Cod live in shallow water approximately 20 meters. South of Cape Cod, populations live in deeper water ranging from 40 to 200 meters.

Deep sea scallops range in length from 10 to 23 centimeters (4 to 9 inches), with their average length being 15 centimeters (6inches). According to Animal Diversity Web: Deep sea scallop shells consist of two valves, which are large, thick, and oval-shaped. This shell is often greater in height than width. The valves are unequal in size, with the lower being almost flat and the upper being convex. Grooves radiate from the hinge towards the shell edge. The upper valve is dark in color, usually red or pinkish brown and sometimes rayed with white, while the lower is lighter and is pinkish white. The shell's inside is a glossy white with a distinctive muscular scar where the soft body attaches. The muscle itself is white or tan in color and has two labial or feeding palps with a mouth in between. The scallop's body is wedge-shaped with a ventrally located foot. The gills or ctenidia are in the mantle cavity and are commonly enlarged and have a complex arrangement. A row of eyes peaks from in between the the valves and are attached to the mantle cavity.

Sea Scallops

Atlantic sea scallops (Scientific name: Placopecten magellanicus) are also known as scallops, sea scallops and giant scallops. They have saucer-shaped shells with scalloped or fluted edges. The upper shell is usually reddish-pink or brown in color. The lower shell is white or cream. A small percentage (5-10 percent) of sea scallops are albinos, with white upper and lower shells. Sea scallop shells are smooth and lack the prominent ribbing that is characteristic of most other scallop shells. It is thought that the sea scallop’s smooth shell is an adaptation to allow it to propel itself faster and farther. [Source: NOAA]

Atlantic sea scallops are found in the Northwest Atlantic Ocean, from Newfoundland to Cape Hatteras, North Carolina. Adult scallops live close together in groups called “beds,” on sandy or gravelly parts of the ocean floor. They are generally found at depths of about 30 to 100 meters (100 to 33)0 feet on Georges Bank and in the Mid-Atlantic. Sea scallops can be found in shallower waters in Maine and Canada..

The largest Atlantic scallop ever reported was about 23 centimeters (nine inches) in shell width, but they typically don’t grow larger than 15 centimeters (6 inches). Sea scallops feed by filtering phytoplankton or other small organisms out of the water column, which can actually help to improve water quality by removing suspended materials. Many kinds of pelagic fish and invertebrates eat scallop larvae. Cod, wolffish, eel pout, flounder, crabs, lobster, sea turtles, and sea stars feed on juvenile and adult scallops.

Sea scallops can reproduce by age two, but don’t produce many eggs or sperm until they are about four years old. They are very fertile — a female sea scallop can produce hundreds of millions of eggs per year. For this reason, scallops may respond more rapidly to management actions than species that reproduce slowly and in small numbers. Sea scallops usually spawn in late summer or early fall. They also may spawn in the spring, especially in the Mid-Atlantic Bight. After hatching, scallop larvae remain in the water column for 4 to 6 weeks before settling on the ocean floor.

Sea Scallop Fishing

The U.S. sea scallop fishery is extremely important to the U.S. economy and is the largest wild scallop fishery in the world. In 2021, the commercial landings in the U.S. of Atlantic sea scallop totaled 19.5 million (43 million pounds) of sea scallop meats and were valued at $670 million, according to the NOAA Fisheries commercial fishing landings database. The principal U.S. commercial fisheries for sea scallop are in the Mid-Atlantic (from Virginia to Long Island, New York) and on Georges Bank and neighboring areas, such as the Great South Channel and Nantucket Shoals. There is also a small, primarily inshore fishery for sea scallops in the Gulf of Maine. Scallop vessels from Massachusetts, Virginia, and New Jersey are responsible for the majority of the U.S. harvest. [Source: NOAA]

There are above target population levels. The fishing rate is at recommended level. Area closures and gear restrictions protect habitat that are affected by some kinds of trawl and dredge gear. Regulations are in place to minimize bycatch. Population Status: According to the 2020 stock assessment, Atlantic sea scallops are not overfished and are not subject to overfishing.

U.S. commercial fishermen harvest sea scallops year-round, primarily using turtle deflector–style scallop dredges that catch scallops much like rakes collect leaves. A small number of fishermen use otter trawls, mostly in the Mid-Atlantic. Divers and Digby dredges are sometimes used in near-shore areas in the Gulf of Maine. The bottom fishing gears used to harvest scallops, such as dredges and trawls, can remove some bottom habitat–forming organisms, including tubeworms and sponges.

Managers have implemented a variety of measures to protect habitat from potential impacts of fishing gear: 1) Several areas are closed year-round to harvesting scallops to protect sensitive habitat. 2) Managers have implemented a rotational access area program, which restricts where and when scallop vessels can fish, benefitting both habitat and scallop populations. 3) Fishermen use 4-inch rings in their scallop dredges that increase the dredges’ efficiency, catching larger scallops and allowing smaller scallops and other small marine life to return to the sea floor by passing through the dredge rings. The 4-inch rings reduce the amount of time dredges contact the bottom. 4) Sea turtles, finfish (such as yellowtail flounder, skates, and monkfish), and undersized scallops can be incidentally caught in the scallop fishery. 5) Managers seasonally prohibit fishing in areas where finfish species congregate, reducing catch of these untargeted species.

Scallop vessels in the Mid-Atlantic must use a turtle deflector dredge and chain mat when and where sea turtles occur on scallop grounds. The turtle deflector dredge excludes sea turtles from being caught in the dredge and prevents serious injuries to the turtles. Scallop dredges using “twine-tops” must adhere to gear modifications designed to allow fish to escape.

"Birth of Venus" (1485–1486) by Sandro Botticelli

Scallop Shells Recycled as Chalk

In July 2010, the Yomiuri Shimbun reported: “A Kawasaki-based company has been chalking up success--literally--by turning scallop shells destined for the garbage heap into high-quality chalk that has brightened classroom blackboards in Japan and South Korea. [Source: Yomiuri Shimbun, July 7, 2010]

Nihon Rikagaku Industry Co. developed the chalk by mixing fine powder from crushed scallop shells with calcium carbonate, a conventional chalk material. The chalk has won over schoolteachers and other users for its brilliant colors and ease of use, and has helped recycle scallop shells, disposal of which was once a major problem for scallop farmers.

About 30 workers at the company's factory in Bibai, a major scallop production center, churn out about 150,000 sticks of chalk a day, using about 2.7 million scallop shells annually. Nihon Rikagaku, like most chalk manufacturers, previously made chalk solely from calcium carbonate, which comes from limestone. Nishikawa hit on the idea of using scallop shell powder after receiving an overture in 2004 from the Hokkaido Research Organization, a Hokkaido government-run body for regional industrial promotion, for a joint research program on recycling fishery shells.

Scallop shells are rich in calcium carbonate. But sea alga and gunk that builds up on the shell surface must be removed before the shells can begin their chalky transformation. "Removing the gunk by hand was very costly, so we decided to do it using a burner instead," he said. Nishikawa, 56, subsequently invented a method of pounding the shells into minute particles just a few micrometers across. A micrometer is one-thousandth of a millimeter. Finding the optimum ratio of shell powder and calcium carbonate also gave Nishikawa a few sleepless nights.

An early 6-to-4 mix of shell powder and calcium carbonate was too fragile and crumbled when used for writing. So Nishikawa reduced the shell powder to just 10 percent of the mix, a blend that ultimately produced chalk that was easy to write with."At that ratio, crystals in the shell powder act as a cement holding the chalk together," Nishikawa said. Schoolteachers and others have praised the new chalk for how smoothly it writes, he said.

Scallop shells are an abundant resource. About 3.13 million tons of fishery products, including fish innards and shells, were discarded in 2008, according to the Agriculture, Forestry and Fisheries Ministry. About 380,000 tons--half of that amount being scallop shells--were thrown away in Hokkaido in fiscal 2008, a Hokkaido government official said. Most scallop shells were discarded until about a decade ago. These days, more than 99 percent are recycled for soil improvement and other uses.

Image Sources: Wikimedia Commons, NOAA

Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.

Last Updated April 2023