Scallop

Distribution and habitat

Scallops inhabit all the oceans of the world, with the largest number of species living in the Indo-Pacific region. Most species live in relatively shallow waters from the low tide line to 100 m, while others prefer much deeper water. Although some species only live in very narrow environments, most are opportunistic and can live under a wide variety of conditions. Scallops can be found living within, upon, or under either rocks, coral, rubble, sea grass, kelp, sand, or mud. Most scallops begin their lives as byssally attached juveniles, an ability that some retain throughout their lives while others grow into free-living adults.^[3]

Anatomy and physiology

Very little variation occurs in the internal arrangement of organs and systems within the scallop family, and what follows can be taken to apply to the anatomy of any given scallop species.^[4]

Orientation

Anatomical diagram of an Atlantic bay scallop with the left (i.e., upper) valve removed; anterior is to the left, posterior to the right

The shell of a scallop consists of two sides or valves, a left valve and a right one, divided by a plane of symmetry.^[5] Most species of scallops rest on their right valve, and consequently, this valve is often deeper and more rounded than the left (i.e., upper) valve, which in many species is actually concave. With the hinge of the two valves oriented towards the top, one side corresponds to the animal's morphological anterior or front, the other is the posterior or rear, the hinge is the dorsal or back/top region, and the bottom corresponds to the ventral or (as it were) underside/belly.^[6] However, as many scallop shells are more or less bilaterally symmetrical ("equivalved"), as well as symmetrical front/back ("equilateral"), determining which way a given animal is "facing" requires detailed information about its valves.

Valves

Diagram of a scallop with two differently sized valves shown positioned in ocean floor sediment: the right valve (shown at the bottom) much deeper than the left, allowing the scallop to appear less visible to predators

The model scallop shell consists of two similarly shaped valves with a straight hinge line along the top, devoid of teeth, and producing a pair of flat wings or "ears" (sometimes called "auricles", though this is also the term for two chambers in its heart) on either side of its midpoint, a feature which is unique to and apparent in all adult scallops.^[7] These ears may be of similar size and shape, or the anterior ear may be somewhat larger (the posterior ear is never larger than the anterior one, an important feature for distinguishing which valve is which). As is the case in almost all bivalves, a series of lines and/or growth rings originates at the center of the hinge, at a spot called the "beak" surrounded by a generally raised area called the "umbo". These growth rings increase in size downwards until they reach the curved ventral edge of the shell. The shells of most scallops are streamlined to facilitate ease of movement during swimming at some point in their lifecycles, while also providing protection from predators. Scallops with ridged valves have the advantage of the architectural strength provided by these ridges called "ribs", although the ribs are somewhat costly in weight and mass. A unique feature of the scallop family is the presence, at some point during the animal's lifecycle, of a distinctive and taxonomically important shell feature, a comb-like structure called a ctenolium located on the anterior edge of the right valve next to the valve's byssal notch. Though many scallops lose this feature as they become free-swimming adults, all scallops have a ctenolium at some point during their lives, and no other bivalve has an analogous shell feature. The ctenolium is found in modern scallops only; both putative ancestors of modern scallops, the entoliids and the Aviculopectinidae, did not possess it.^[8]

Muscular system

A live opened scallop showing the internal anatomy: The pale orange circular part is the adductor muscle; the darker orange curved part is the "coral", a culinary term for the ovary or roe.

Like the true oysters (family Ostreidae), scallops have a single central adductor muscle, thus, the inside of their shells has a characteristic central scar, marking the point of attachment for this muscle. The adductor muscle of scallops is larger and more developed than those of oysters, because scallops are active swimmers; some species of scallops are known to move en masse from one area to another. In scallops, the shell shape tends to be highly regular, and is commonly used as an archetypal form of a seashell.^[6]

Digestive system

Scallops are filter feeders, and eat plankton. Unlike many other bivalves, they lack siphons. Water moves over a filtering structure, where food particles become trapped in mucus. Next, the cilia on the structure move the food toward the mouth. Then, the food is digested in the digestive gland, an organ sometimes misleadingly referred to as the "liver, " which envelops part of the oesophagus, intestine, and entire stomach. Waste is passed on through the intestine (the terminus of which, like that of many mollusks, enters and leaves the animal's heart) and exits via the anus.^[6]: p.20

Nervous system

Neural map of a giant scallop

Like all bivalves, scallops lack actual brains. Instead, their nervous system is controlled by three paired ganglia located at various points throughout their anatomy, the cerebral or cerebropleural ganglia, the pedal ganglia, and the visceral or parietovisceral ganglia. All are yellowish. The visceral ganglia are by far the largest and most extensive of the three, and occur as an almost-fused mass near the center of the animal – proportionally, these are the largest and most intricate sets of ganglia of any modern bivalve. From this, radiate all of the nerves which connect the visceral ganglia to the circumpallial nerve ring which loops around the mantle and connects to all of the scallop's tentacles and eyes. This nerve ring is so well developed that, in some species, it may be legitimately considered an additional ganglion.^[6]: p.46 The visceral ganglia are also the origin of the branchial nerves which control the scallop's gills. The cerebral ganglia are the next-largest set of ganglia and lie distinct from each other a significant distance dorsal to the visceral ganglia. They are attached to the visceral ganglia by long cerebral-visceral connectives, and to each other via a cerebral commissure that extends in an arch dorsally around the esophagus. The cerebral ganglia control the scallop's mouth via the palp nerves and connect to statocysts which help the animal sense its position in the surrounding environment. They are connected to the pedal ganglia by short cerebral-pedal connectives. The pedal ganglia, though not fused, are situated very close to each other near the midline. From the pedal ganglia, the scallop puts out pedal nerves which control the movement of, and sensation in, its small muscular foot.^{[6]: pp. 43–47}

Reproduction

The scallop family is unusual in that some members of the family are dioecious (males and females are separate), while others are simultaneous hermaphrodites (both sexes in the same individual), and a few are protoandrous hermaphrodites (males when young then switching to female). Red roe is that of a female, and white, is that of a male. Spermatozoa and ova are released freely into the water during mating season and fertilized ova sink to the bottom. After several weeks, the immature scallops hatch and the larvae, miniature transparent versions of the adults called "spat", drift in the plankton until settling to the bottom again (an event called spatfall) to grow, usually attaching by means of byssal threads. Some scallops, such as the Atlantic bay scallop Argopecten irradians, are short-lived, while others can live 20 years or more. Age can often be inferred from annuli, the concentric rings of their shells.^[6]

Eyes

Closeups of the iridescent blue eyes of the bay scallop, Argopecten irradians ^[9]

Scallops have a large number (up to 200) of small (about 1 mm) eyes arranged along the edge of their mantles. These eyes represent a particular innovation among molluscs, relying on a concave, parabolic mirror of guanine crystals to focus and retro-reflect light instead of a lens as found in many other eye types.^[10] Additionally, their eyes possess a double-layered retina, the outer retina responding most strongly to light and the inner to abrupt darkness.^[11] While these eyes are unable to resolve shapes with high fidelity, the combined sensitivity of both retinas to light entering the eye and light retro-reflected from the mirror grants scallops exceptional contrast definition, as well as the ability to detect changing patterns of light and motion.^[12][13] Scallops primarily rely on their eyes as an 'early-warning' threat detection system, scanning around them for movement and shadows which could potentially indicate predators. Additionally, some scallops alter their swimming or feeding behaviour based on the turbidity or clarity of the water, by detecting the movement of particulate matter in the water column.^[14]

Adductor muscles

Adductor muscles of a scallop. a: photo in a live scallop. b: after removal of organs and tissues.

Scallops possess fast (striated) and slow (smooth) adductor muscles, which have different structures and contractile properties. These muscles lie closely apposed to one another but are divided by a connective tissue sheet. The striated adductor muscle contracts very quickly for swimming, whereas the smooth catch adductor muscle lacks striations, and contracts for long periods, keeping shells closed with little expenditure of energy.^[15]

Locomotion

Overhead view of a scallop engaged in a zig-zag swimming motion

Overhead view of a scallop engaged in a unidirectional jumping motion

Scallops are mostly free-living and active, unlike the vast majority of bivalves, which are mostly slow-moving and infaunal. All scallops are thought to start out with a byssus, which attaches them to some form of substrate such as eelgrass when they are very young. Most species lose the byssus as they grow larger. A very few species go on to cement themselves to a hard substrate (e.g. Chlamys distorta and Hinnites multirigosus).^[16]

However, the majority of scallops are free-living and can swim with brief bursts of speed to escape predators (mostly starfish) by rapidly opening and closing their valves. Indeed, everything about their characteristic shell shape – its symmetry, narrowness, smooth and/ or grooved surface, small flexible hinge, powerful adductor muscle, and continuous and uniformly curved edge – facilitates such activity. They often do this in spurts of several seconds before closing the shell entirely and sinking back to the bottom of their environment. Scallops are able to move through the water column either forward/ventrally (termed swimming) by sucking water in through the space between their valves, an area called the gape, and ejecting it through small holes near the hinge line called exhalant apertures, or backward/dorsally (termed jumping) by ejecting the water out the same way it came in (i.e. ventrally). A jumping scallop usually lands on the sea floor between each contraction of its valves, whereas a swimming scallop stays in the water column for most or all of its contractions and travels a much greater distance (though seldom at a height of more than 1 m off the sea bed and seldom for a distance of greater than 5 m).^[16] Both jumping and swimming movements are very energy-intensive, and most scallops cannot perform more than four or five in a row before becoming completely exhausted and requiring several hours of rest. Should a swimming scallop land on its left side, it is capable of flipping itself over to its right side via a similar shell-clapping movement called the righting reflex. So-called singing scallops are rumored to make an audible, soft popping sound as they flap their shells underwater (though whether or not this happens is open to some debate).^[17] Other scallops can extend their foot from between their valves, and by contracting the muscles in their foot, they can burrow into sand.^[18]

Mobility and behavior

Most species of the scallop family are free-living, active swimmers, propelling themselves through the water through the adductor muscles to open and close their shells. Swimming occurs through the clapping of valves for water intake. Closing the valves propels water with a strong force near the hinge via the velum, a curtain-like fold of the mantle that directs water expulsion around the hinge. Scallops swim in the direction of the valve opening unless the velum directs an abrupt change in course direction.^[19][20]

Other species of scallops can be found on the ocean floor attached to objects by byssal threads. Byssal threads are strong, silky fibers extending from the muscular foot, used to attach to a firm support, such as a rock. Some can also be found on the ocean floor, moving with an extendable foot between their valves or burrowing themselves in the sand by extending and retracting their feet.^[6] Scallops are highly sensitive to shadows, vibrations, water movement, and chemical stimuli.^[21] All possess a series of 100 blue eyes, embedded on the edge of the mantle of their upper and lower valves that can distinguish between light and darkness. They serve as a vital defense mechanism for avoiding predators. Though rather weak, their series of eyes can detect surrounding movement and alert precaution in the presence of predators, most commonly sea stars, crabs, and snails.^[6] Physiological fitness and exercise of scallops decrease with age due to the decline of cellular and especially mitochondrial function,^[22] thus increasing the risk of capture and lowering rates of survival. Older individuals show lower mitochondrial volume density and aerobic capacity, as well as decreased anaerobic capacity construed from the amount of glycogen stored in muscle tissue.^[22] Environmental factors, such as changes in oxidative stress parameters, can inhibit the growth and development of scallops.^[23]

Seasonal changes in temperature and food availability have been shown to affect muscle metabolic capabilities. The properties of mitochondria from the phasic adductor muscle of Euvola ziczac varied significantly during their annual reproductive cycle. Summer scallops in May have lower maximal oxidative capacities and substrate oxidation than any other time in the year. This phenomenon is due to lower protein levels in adductor muscles.^[24]

Pearls

A scallop pearl

Scallops do occasionally produce pearls, though scallop pearls do not have the buildup of translucent layers or "nacre" which give desirability to the pearls of the feather oysters, and usually lack both lustre and iridescence. They can be dull, small, and of varying colour, but exceptions occur that are appreciated for their aesthetic qualities.^[25]

Mutualism

Some scallops, including Chlamys hastata, frequently carry epibionts such as sponges and barnacles on their shells. The relationship of the sponge to the scallop is characterized as a form of mutualism, because the sponge provides protection by interfering with adhesion of predatory sea-star tube feet,^[26][27][28] camouflages Chlamys hastata from predators,^[27] or forms a physical barrier around byssal openings to prevent sea stars from inserting their digestive membranes.^[28] Sponge encrustation protects C. hastata from barnacle larvae settlement, serving as a protection from epibionts that increase susceptibility to predators. Thus, barnacle larvae settlement occurs more frequently on sponge-free shells than on sponge-encrusted shells.^[26]

In fact, barnacle encrustation negatively influences swimming in C. hastata. Those swimming with barnacle encrustation require more energy and show a detectable difference in anaerobic energy expenditure than those without encrustation. In the absence of barnacle encrustation, individual scallops swim significantly longer, travel further, and attain greater elevation.^[29]

Lifecycle and growth

Many scallops are hermaphrodites (having female and male organs simultaneously), altering their sex throughout their lives, while others exist as dioecious species, having a definite sex. In this case, males are distinguished by roe-containing white testes and females with roe-containing orange ovaries. At the age of two, they usually become sexually active, but do not contribute significantly to egg production until four. The reproduction process occurs externally through spawning, in which eggs and sperm are released into the water. Spawning typically occurs in late summer and early autumn; spring spawning may also take place in the Mid-Atlantic Bight.^[30] The females of scallops are highly fecund, capable of producing hundreds of millions of eggs per year.^[30]

Once an egg is fertilized, it is then planktonic, a collection of microorganisms that drift abundantly in fresh or salt water. Larvae stay in the water column for four to seven weeks before dissipating to the ocean floor, where they attach themselves to objects through byssus threads. Byssus is eventually lost with adulthood, transitioning almost all scallop species into free swimmers. Rapid growth occurs within the first several years, with an increase of 50–80 % in shell height and quadrupled size in meat weight, and reaches a commercial size at about four to five years of age.^[30] The lifespans of some scallops have been known to extend over 20 years.^[31]

Taxonomy and phylogeny

Etymology

The family name Pectinidae, which is based on the name of the type genus, Pecten, comes from the Latin pecten meaning comb, in reference to a comb-like structure of the shell which is situated next to the byssal notch.^[32]

Phylogeny

Fossil scallop Chlamys with encrusters; Nicosia Formation (Pliocene) of Cyprus

The fossil history of scallops is rich in species and specimens. The earliest known records of true scallops (those with a ctenolium) can be found from the Triassic period, over 200 million years ago.^[8] The earliest species were divided into two groups, one with a nearly smooth exterior: Pleuronectis von Schlotheim, 1820, while the other had radial ribs or riblets and auricles: Praechlamys Allasinaz, 1972.^[33] Fossil records also indicate that the abundance of species within the Pectinidae has varied greatly over time; Pectinidae was the most diverse bivalve family in the Mesozoic era, but the group almost disappeared completely by the end of the Cretaceous period. The survivors speciated rapidly during the Tertiary period. Nearly 7,000 species and subspecies names have been introduced for both fossil and recent Pectinidae.^[34]

The cladogram is based on molecular phylogeny using mitochondrial (12S, 16S) and nuclear (18S, 28S, and H3) gene markers by Yaron Malkowsky and Annette Klussmann-Kolb in 2012.^[35]

Taxonomic structure

Scallops are the family Pectinidae, marine bivalve molluscs within the superfamily Pectinoidea. Other families within this same superfamily share a somewhat similar overall shell shape, and some species within some of the related families are also commonly referred to as "scallops" (for example, Propeamussiidae, the glass scallops).

The family Pectinidae is the most diversified of the pectinoideans in present-day oceans. It is one of the largest marine bivalve families and contains over 300 extant species in 60 genera. Its origin dates back to the Middle Triassic Period, approximately 240 million years ago;^[8] in terms of diversity, it has been a thriving family to the present day.^[36]

Evolution from its origin has resulted in a successful and diverse group: pectinids are present in the world's seas, found in environments ranging from the intertidal zone to the hadal depths. The Pectinidae play an extremely important role in many benthic communities and exhibit a wide range of shell shapes, sizes, sculptures, and cultures.^[37]

Raines and Poppe^[b] listed nearly 900 species names of scallops, but most of these are considered either questionable or invalid. Raines and Poppe mentioned over 50 genera, around 250 species, and subspecies. Although species are generally well-circumscribed, their attribution to subfamilies and genera is sometimes equivocal, and information about phylogeny and relationships of the species are minimal, not the least because most work has been based only on adult morphology.^[39]

This family's earliest and most comprehensive taxonomic treatments were based on macroscopic morphological characters of the adult shells and represent broadly divergent classification schemes.^[40][41] Some level of taxonomic stability was achieved when Waller's studies in 1986, 1991, and 1993 concluded evolutionary relationships between pectinid taxa based on hypothesized morphological synapomorphies, which previous classification systems of Pectinidae failed to do. He created three Pectinidae subfamilies: Camptonectinidae, Chlamydinae and Pectininae.^[42][43][44]

The framework of its phylogeny shows that repeated life habit states derive from evolutionary convergence and parallelism.^[45][46] Studies have determined the family Pectinidae is monophyletic, developing from a single common ancestor. The direct ancestors of Pectinidae were scallop-like bivalves of the family Entoliidae.^[47] Entoliids had auricles and a byssal notch only at youth, but they did not have a ctenolium, a comb-like arrangement along the margins of the byssal notch in Pectinidae. The ctenolium is the defining feature of the modern family Pectinidae and is a characteristic that has evolved within the lineage.^[48]

In a 2008 paper, Puslednik et al. identified considerable convergence of shell morphology in a subset species of gliding Pectinidae, which suggests iterative morphological evolution may be more prevalent in the family than previously believed.^[49]

There have been a number of efforts to address phylogenetic studies. Only three have assessed more than ten species^[50][51][52] and only one has included multiple outgroups.^[51] Nearly all previous molecular analyses of the Pectinidae have only utilized mitochondrial data. Phylogenies based only on mitochondrial sequence data do not always provide an accurate estimation on the species tree. Complicated factors can arise due to the presence of genetic polymorphisms in ancestral species and resultant lineage sorting.^[53][54]

In molecular phylogenies of the Bivalvia, both the Spondylidae and the Propeamussiidae have been resolved as sister to the Pectinidae.^[51][55]

List of subfamilies and genera

Bractechlamys vexillum

Pecten tigris Lamarck, 1819, museum specimens

The following are recognised in the family Pectinidae:

Pearl nets used to grow spat to juveniles in scallop aquaculture

Discover more about Biology related topics

Indo-Pacific

Indo-Pacific

The Indo-Pacific is a vast biogeographic region of Earth.

Kelp

Kelp

Kelps are large brown algae seaweeds that make up the order Laminariales. There are about 30 different genera. Despite its appearance, kelp is not a plant - it is a heterokont, a completely unrelated group of organisms.

Byssus

Byssus

A byssus is a bundle of filaments secreted by many species of bivalve mollusc that function to attach the mollusc to a solid surface. Species from several families of clams have a byssus, including pen shells (Pinnidae), true mussels (Mytilidae), and Dreissenidae.

Beak (bivalve)

Beak (bivalve)

The beak is part of the shell of a bivalve mollusk, i.e. part of the shell of a saltwater or freshwater clam. The beak is the basal projection of the oldest part of the valve of the adult animal. The beak usually, but not always, coincides with the umbo, the highest and most prominent point on the valve. Because by definition, all bivalves have two valves, the shell of a bivalve has two umbones, and two beaks.

Entoliidae

Entoliidae

The Entoliidae, also referred to as the entoliids, are a taxonomic family of saltwater clams, marine bivalve mollusks in the order Pectinida. They are related to and are considered the ancestors of modern scallops. In the geological record the family contains at least seven species in five different genera, though only one is extant and it is very rare and cryptic, inhabiting the Caribbean and central west Pacific Ocean in small, disjointed populations.

Roe

Roe

Roe or hard roe is the fully ripe internal egg masses in the ovaries, or the released external egg masses, of fish and certain marine animals such as shrimp, scallop, sea urchins and squid. As a seafood, roe is used both as a cooked ingredient in many dishes, and as a raw ingredient for delicacies such as caviar.

Ostreidae

Ostreidae

The Ostreidae, the true oysters, include most species of molluscs commonly consumed as oysters. Pearl oysters are not true oysters, and belong to the order Pteriida.

Oyster

Oyster

Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but not all oysters are in the superfamily Ostreoidea.

Archetype

Archetype

The concept of an archetype appears in areas relating to behavior, historical psychology, and literary analysis.

Seashell

Seashell

A seashell or sea shell, also known simply as a shell, is a hard, protective outer layer usually created by an animal or organism that lives in the sea. The shell is part of the body of the animal. Empty seashells are often found washed up on beaches by beachcombers. The shells are empty because the animal has died and the soft parts have decomposed or been eaten by another animal.

Filter feeder

Filter feeder

Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feeding are clams, krill, sponges, baleen whales, and many fish. Some birds, such as flamingos and certain species of duck, are also filter feeders. Filter feeders can play an important role in clarifying water, and are therefore considered ecosystem engineers. They are also important in bioaccumulation and, as a result, as indicator organisms.

Plankton

Plankton

Plankton are the diverse collection of organisms found in water that are unable to propel themselves against a current. The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucial source of food to many small and large aquatic organisms, such as bivalves, fish and whales.

Aquaculture

Wild fisheries

The largest wild scallop fishery is for the Atlantic sea scallop (Placopecten magellanicus) found off the northeastern United States and eastern Canada. Scallops are harvested using scallop dredges or bottom trawls. Most of the rest of the world's production of scallops is from Japan (wild, enhanced, and aquaculture) and China (mostly cultured Atlantic bay scallops).^{[57]: p.661}

In the D'Entrecasteaux Channel in the south of Tasmania dredging was banned in 1969, and since then divers have caught them in this area.^[58] Attempts to use lighted pots to attract lobster and crab led to the discovery that they were effective in attracting scallops.^[59]

Sustainability

The scallop fishery in New Zealand declined from a catch of 1246 tonnes in 1975 to 41 tonnes in 1980, at which point the government ordered the fishery closed. Spat seeding in the 1980s helped it recover, and catches in the 1990s were up to 684 tonnes.^[60] The Tasman Bay / Te Tai-o-Aorere area was closed to commercial scallop harvesting from 2009 to 2011 due to a decline in the numbers. The commercial catch was down to 22 tonnes in 2015, and the fishery was closed again. The main causes for the decline seem to be fishing, climate effects, disease, pollutants, and sediment runoff from farming and forestry.^[60] Forest and Bird list scallops as the "Worst Choice" in their Best Fish Guide for sustainable seafood species.^[61]

On the east coast of the United States, over the last 100 years, the populations of bay scallops have greatly diminished due to several factors but probably mostly due to a reduction in seagrasses (to which bay scallop spat attach) caused by increased coastal development and concomitant nutrient runoff. Another possible factor is the reduction of sharks from overfishing. A variety of sharks used to feed on rays, which are the main predator of bay scallops. With the shark population reduced – this apex predator in some places almost eliminated – the rays have been free to feed on scallops to greatly decrease their numbers.^[62] By contrast, the Atlantic sea scallop (Placopecten magellanicus) is at historically high levels of abundance after recovery from overfishing.^[63]

Discover more about Seafood industry related topics

Scallop aquaculture

Scallop aquaculture

Scallop aquaculture is the commercial activity of cultivating (farming) scallops until they reach a marketable size and can be sold as a consumer product. Wild juvenile scallops, or spat, were collected for growing in Japan as early as 1934. The first attempts to fully cultivate scallops in farm environments were not recorded until the 1950s and 1960s. Traditionally, fishing for wild scallops has been the preferred practice, since farming can be expensive. However worldwide declines in wild scallop populations have resulted in the growth of aquaculture. Globally the scallop aquaculture industry is now well established, with a reported annual production totalling over 1,200,000 metric tonnes from about 12 species. China and Japan account for about 90% of the reported production.

Placopecten magellanicus

Placopecten magellanicus

Placopecten magellanicus, previously listed as Pecten tenuicostatus and as Pecten grandis and once referred to as the "giant scallop", common names Atlantic deep-sea scallop, deep sea scallop, North Atlantic sea scallop, American sea scallop, Atlantic sea scallop, or sea scallop, is a commercially important pectinid bivalve mollusk native to the northwest Atlantic Ocean.

D'Entrecasteaux Channel

D'Entrecasteaux Channel

The D'Entrecasteaux Channel is a body of water located between Bruny Island and the south-east of the mainland of Tasmania, Australia. The channel is the mouth for the estuaries of the Derwent and the Huon Rivers and empties into the Tasman Sea of the South Pacific Ocean. It was sighted by Abel Tasman in 1642 and surveyed in 1792 by Bruni d'Entrecasteaux.

Scuba diving

Scuba diving

Scuba diving is a mode of underwater diving whereby divers use breathing equipment that is completely independent of a surface air supply. The name "scuba", an acronym for "Self-Contained Underwater Breathing Apparatus", was coined by Christian J. Lambertsen in a patent submitted in 1952. Scuba divers carry their own source of breathing gas, usually compressed air, affording them greater independence and movement than surface-supplied divers, and more time underwater than free divers. Although the use of compressed air is common, a gas blend with a higher oxygen content, known as enriched air or nitrox, has become popular due to the reduced nitrogen intake during long and/or repetitive dives. Also, breathing gas diluted with helium may be used to reduce the likelihood and effects of nitrogen narcosis during deeper dives.

Lobster

Lobster

Lobsters are a family of marine crustaceans. They have long bodies with muscular tails and live in crevices or burrows on the sea floor. Three of their five pairs of legs have claws, including the first pair, which are usually much larger than the others. Highly prized as seafood, lobsters are economically important and are often one of the most profitable commodities in the coastal areas they populate.

Crab

Crab

Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen), usually hidden entirely under the thorax. They live in all the world's oceans, in freshwater, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers. They first appeared during the Jurassic Period.

United States

United States

The United States of America, commonly known as the United States or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, nine Minor Outlying Islands, and 326 Indian reservations. The United States is also in free association with three Pacific Island sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Republic of Palau. It is the world's third-largest country by both land and total area. It shares land borders with Canada to its north and with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 million, it is the most populous country in the Americas and the third most populous in the world. The national capital of the United States is Washington, D.C. and its most populous city and principal financial center is New York City.

Batoidea

Batoidea

Batoidea is a superorder of cartilaginous fishes, commonly known as rays. They and their close relatives, the sharks, comprise the subclass Elasmobranchii. Rays are the largest group of cartilaginous fishes, with well over 600 species in 26 families. Rays are distinguished by their flattened bodies, enlarged pectoral fins that are fused to the head, and gill slits that are placed on their ventral surfaces.

Apex predator

Apex predator

An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own.

Scallops with wine sauce

Wikimedia Commons has media related to Scallop dishes.

Scallops are characterized by offering two flavors and textures in one shell: the meat, called "scallop", which is firm and white, and the roe, called "coral", which is soft and often brightly coloured reddish-orange. Sometimes, markets sell scallops already prepared in the shell, with only the meat remaining. Outside the U.S., the scallop is often sold whole. They are available both with and without coral in the UK and Australia.^[64]

Scallops without any additives are called "dry-packed", while scallops that are treated with sodium tripolyphosphate (STPP) are called "wet-packed". STPP causes the scallops to absorb moisture prior to the freezing process, thereby increasing their weight. The freezing process takes about two days.^[65]

In Galician cuisine, scallops are baked with breadcrumbs, ham, and onions. In Japanese cuisine, scallops may be served in soup or prepared as sashimi or sushi. In a sushi bar, hotategai (帆立貝, 海扇) is the traditional scallop on rice and, while kaibashira (貝柱) may be calscallop is more loosely used to include other shellfish species with round-shaped flesh (the adductor muscle), such as Atrina (帶子). Dried scallop is known in Cantonese Chinese cuisine as conpoy (乾瑤柱, 乾貝, 干貝). Smoked scallops are sometimes served as appetizers or used as an ingredient in the preparation of various dishes and appetizers.^[66]

Scallops have lent their name to the culinary term "scalloped", which originally referred to seafood creamed and served hot in the shell.^[67] Today, it means a creamed casserole dish such as scalloped potatoes, which contains no seafood at all.

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  Adductor muscle meat of the giant scallop (seven white circular items) with a large shrimp

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  Dried scallops, also known as conpoy

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  Taiwanese steamed scallops

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  A scallop being grilled next to sausages in Japan

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  Fried scallops on a stick served with rice

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  Pan seared scallops

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Wine sauce

Wine sauce

Wine sauce is a culinary sauce prepared with wine as a primary ingredient, heated and mixed with stock, butter, herbs, spices, onions, garlic and other ingredients. Several types of wines may be used, including red wine, white wine and port wine. Some versions are prepared using a reduction. Several types of wine sauces exist, and it is used in many dishes, including those prepared with seafood, poultry and beef. Wine sauces are associated with French cuisine.

Galician cuisine

Galician cuisine

Galician cuisine refers to the typical dishes and ingredients found in the cuisine of the autonomous community of Galicia, Spain. These include shellfish, empanadas, polbo á feira, cheese queixo de tetilla, ribeiro and albariño wines, and orujo liquor. Similarly, to Asturian cuisine, Galician dishes have maintained several Celtic links, namely with different stews.

Japanese cuisine

Japanese cuisine

Japanese cuisine encompasses the regional and traditional foods of Japan, which have developed through centuries of political, economic, and social changes. The traditional cuisine of Japan is based on rice with miso soup and other dishes; there is an emphasis on seasonal ingredients. Side dishes often consist of fish, pickled vegetables, and vegetables cooked in broth. Seafood is common, often grilled, but also served raw as sashimi or in sushi. Seafood and vegetables are also deep-fried in a light batter, as tempura. Apart from rice, a staple includes noodles, such as soba and udon. Japan also has many simmered dishes, such as fish products in broth called oden, or beef in sukiyaki and nikujaga.

Sashimi

Sashimi

Sashimi is a Japanese delicacy consisting of fresh raw fish or meat sliced into thin pieces and often eaten with soy sauce.

Sushi

Sushi

Sushi is a Japanese dish of prepared vinegared rice , usually with some sugar and salt, accompanied by a variety of ingredients , such as seafood, often raw, and vegetables. Styles of sushi and its presentation vary widely, but the one key ingredient is "sushi rice", also referred to as shari (しゃり), or sumeshi (酢飯).

Atrina

Atrina

Atrina is a cosmopolitan genus of bivalve molluscs belonging to the family Pinnidae.

Cantonese cuisine

Cantonese cuisine

Cantonese or Guangdong cuisine, also known as Yue cuisine is the cuisine of Guangdong province of China, particularly the provincial capital Guangzhou, and the surrounding regions in the Pearl River Delta including Hong Kong and Macau. Strictly speaking, Cantonese cuisine is the cuisine of Guangzhou or of Cantonese speakers, but it often includes the cooking styles of all the speakers of Yue Chinese languages in Guangdong. Scholars categorize Guangdong cuisine into three major groups based on the region's dialect: Cantonese, Hakka and Chaozhou cuisines.

Chinese cuisine

Chinese cuisine

Chinese cuisine encompasses the numerous cuisines originating from China, as well as overseas cuisines created by the Chinese diaspora. Because of the Chinese diaspora and historical power of the country, Chinese cuisine has influenced many other cuisines in Asia and beyond, with modifications made to cater to local palates. Chinese food staples such as rice, soy sauce, noodles, tea, chili oil, and tofu, and utensils such as chopsticks and the wok, can now be found worldwide.

Conpoy

Conpoy

Conpoy or dried scallop is a type of Cantonese dried seafood product that is made from the adductor muscle of scallops. The smell of conpoy is marine, pungent, and reminiscent of certain salt-cured meats. Its taste is rich in umami due to its high content of various free amino acids, such as glycine, alanine, and glutamic acid. It is also rich in nucleic acids such as inosinic acid, amino acid byproducts such as taurine, and minerals, such as calcium and zinc.

Smoked scallop

Smoked scallop

Smoked scallops are scallops that have been smoked. A scallop is a common name applied to many species of marine bivalve mollusks in the family Pectinidae, the scallops. Scallops are a cosmopolitan family, found in all of the world's oceans.

Pecten maximus

Pecten maximus

Pecten maximus, common names the great scallop, king scallop, St James shell or escallop, is a northeast Atlantic species of scallop, an edible saltwater clam, a marine bivalve mollusc in the family Pectinidae. This is the type species of the genus. This species may be conspecific with Pecten jacobaeus, the pilgrim's scallop, which has a much more restricted distribution.

Saint James by Carlo Crivelli, c. 1480

Shell of Saint James

Shield with symbol of St. James the Great, Church of the Good Shepherd (Rosemont, Pennsylvania)

The scallop shell is the traditional emblem of St James the Great and is popular with pilgrims returning from the Way of St James (Camino de Santiago) and the apostle's shrine at Santiago de Compostela in Galicia, Spain.^[68] Medieval Christians would collect a scallop shell while at Compostela as evidence of having made the journey. The association of Saint James with the scallop can most likely be traced to the legend that the apostle once rescued a knight covered in scallops.^[69] An alternative version of the legend holds that while St. James' remains were being transported to Galicia (Spain) from Jerusalem, the disciples witnessed a bridegroom on horseback fall into the water and emerge covered in the shells.^[70]

Indeed in French, the mollusc itself – as well as a popular preparation of it in cream sauce – is called coquille St. Jacques. In German they are Jakobsmuscheln – literally "James's shellfish". Curiously the Linnaean name Pecten jacobeus is given to the Mediterranean scallop, while the scallop endemic to Galicia is called Pecten maximus due to its bigger size.^[71] The scallop shell is represented in the decoration of churches named after St. James, such as in St James' Church, Sydney, where it appears in a number of places, including in the mosaics on the floor of the chancel.^[72]

When referring to St James, a scallop shell valve is displayed with its convex outer surface showing. In contrast, when the shell refers to the goddess Venus (see below), it is displayed with its concave interior surface showing.^[71]

Shell of Saint Augustine

Saint Augustine is said to have been walking along the seashore, meditating on the unfathomable mystery of the Holy Trinity. A boy was using a shell to pour seawater into a little hole. When Augustine asked what he was doing, he replied, "I am emptying the sea into this hole." Thus did Augustine understand that man would never penetrate to the depths of the mystery of God.^[73]

This symbolic meaning was taken up by Joseph Ratzinger in his coat of arms as Archbishop of Munich, and also retained by him when elected Pope Benedict XVI. While a doctoral candidate in 1953, Ratzinger wrote his dissertation on The People of God and the House of God in Augustine's Teaching, and the shell, therefore, has a personal connection with the thought of Saint Augustine.^[73]

Badge

A scallop shell in a German coat of arms

The scallop shell symbol found its way into heraldry as a badge of those who had been on the pilgrimage to Compostela, although later, it became a symbol of pilgrimage in general. Winston Churchill and Diana, Princess of Wales' family, the Spencer family coat of arms includes a scallop, as well as both of Diana's sons Prince William, Duke of Cambridge and Prince Harry's personal coats of arms; also Pope Benedict XVI's personal coat of arms includes a scallop; another example is the surname Wilmot and also John Wesley's (which as a result the scallop shell is used as an emblem of Methodism). However, charges in heraldry do not always have an unvarying symbolic meaning, and there are cases of arms in which no family member went on a pilgrimage, and the occurrence of the scallop is simply a pun on the name of the armiger (as in the case of Jacques Coeur), or for other reasons.^[74] In 1988, the State of New York in the US chose the bay scallop (Argopecten irradians) as its state shell.^[75]

Fertility symbol

Aphrodite Anadyomene, from Amisos, 1st century BC – 1st century AD

Throughout antiquity, scallops and other hinged shells have symbolized the feminine principle.^[76] Outwardly, the shell can symbolize the protective and nurturing principle, and inwardly, the "life-force slumbering within the Earth",^[77] an emblem of the vulva.^[78][79]

Many paintings of Venus, the Roman goddess of love and fertility, included a scallop shell in the painting to identify her. This is evident in Botticelli's classically inspired 15th century painting The Birth of Venus.^[80]

One legend of the Way of St. James holds that the route was seen as a fertility pilgrimage, undertaken when a young couple desired to bear offspring. The scallop shell is believed to have originally been carried by pagans as a symbol of fertility.^[81][82]

Other interpretations

Alternatively, the scallop resembles the setting sun, which was the focus of the pre-Christian Celtic rituals of the area. To wit, the pre-Christian roots of the Way of St. James was a Celtic death journey westwards towards the setting sun, terminating at the End of the World (Finisterra) on the "Coast of Death" (Costa da Morte) and the "Sea of Darkness" (i.e., the Abyss of Death, the Mare Tenebrosum, Latin for the Atlantic Ocean, itself named after the Dying Civilization of Atlantis).^[83]

Contemporary art

Large sculpture by Maggi Hambling titled The Scallop erected in 2003 on the beach at Aldeburgh, England

The beach at Aldeburgh, Suffolk, England, features Maggi Hambling's steel sculpture, The Scallop, erected in 2003 as a memorial to the composer Benjamin Britten, who had a long association with the town.^[84]

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Carlo Crivelli

Carlo Crivelli

Carlo Crivelli was an Italian Renaissance painter of conservative Late Gothic decorative sensibility, who spent his early years in the Veneto, where he absorbed influences from the Vivarini, Squarcione, and Mantegna. He left the Veneto by 1458 and spent most of the remainder of his career in the March of Ancona, where he developed a distinctive personal style that contrasts with that of his Venetian contemporary Giovanni Bellini.

Church of the Good Shepherd (Rosemont, Pennsylvania)

Church of the Good Shepherd (Rosemont, Pennsylvania)

The Church of the Good Shepherd in Rosemont, Pennsylvania, is a progressive Episcopal parish church in the liberal Anglo-Catholic tradition. It is part of the Episcopal Diocese of Pennsylvania and is located in the Philadelphia Main Line.

Camino de Santiago

Camino de Santiago

The Camino de Santiago, known in English as the Way of St James, is a network of pilgrims' ways or pilgrimages leading to the shrine of the apostle Saint James the Great in the cathedral of Santiago de Compostela in Galicia in northwestern Spain, where tradition holds that the remains of the apostle are buried.

Santiago de Compostela

Santiago de Compostela

Santiago de Compostela or Compostela is the capital of the autonomous community of Galicia, in northwestern Spain. The city has its origin in the shrine of Saint James the Great, now the Cathedral of Santiago de Compostela, as the destination of the Way of St. James, a leading Catholic pilgrimage route since the 9th century. In 1985, the city's Old Town was designated a UNESCO World Heritage Site.

Galicia (Spain)

Galicia (Spain)

Galicia is an autonomous community of Spain and historic nationality under Spanish law. Located in the northwest Iberian Peninsula, it includes the provinces of A Coruña, Lugo, Ourense, and Pontevedra.

Spain

Spain

Spain, or the Kingdom of Spain, is a country primarily located in southwestern Europe with parts of territory in the Atlantic Ocean and across the Mediterranean Sea. The largest part of Spain is situated on the Iberian Peninsula; its territory also includes the Canary Islands in the Atlantic Ocean, the Balearic Islands in the Mediterranean Sea, and the autonomous cities of Ceuta and Melilla in Africa. The country's mainland is bordered to the south by Gibraltar; to the south and east by the Mediterranean Sea; to the north by France, Andorra and the Bay of Biscay; and to the west by Portugal and the Atlantic Ocean. With an area of 505,990 km2 (195,360 sq mi), Spain is the second-largest country in the European Union (EU) and, with a population exceeding 47.4 million, the fourth-most populous EU member state. Spain's capital and largest city is Madrid; other major urban areas include Barcelona, Valencia, Seville, Zaragoza, Málaga, Murcia, Palma de Mallorca, Las Palmas de Gran Canaria, and Bilbao.

Jerusalem

Jerusalem

Jerusalem is a city in Western Asia. Situated on a plateau in the Judaean Mountains between the Mediterranean and the Dead Sea, it is one of the oldest cities in the world and is considered to be a holy city for the three major Abrahamic religions: Judaism, Christianity, and Islam. Both Israelis and Palestinians claim Jerusalem as their capital, as Israel maintains its primary governmental institutions there and the State of Palestine ultimately foresees it as its seat of power. Because of this dispute, neither claim is widely recognized internationally.

Linnaean taxonomy

Linnaean taxonomy

Linnaean taxonomy can mean either of two related concepts:The particular form of biological classification (taxonomy) set up by Carl Linnaeus, as set forth in his Systema Naturae (1735) and subsequent works. In the taxonomy of Linnaeus there are three kingdoms, divided into classes, and they, in turn, into lower ranks in a hierarchical order. A term for rank-based classification of organisms, in general. That is, taxonomy in the traditional sense of the word: rank-based scientific classification. This term is especially used as opposed to cladistic systematics, which groups organisms into clades. It is attributed to Linnaeus, although he neither invented the concept of ranked classification nor gave it its present form. In fact, it does not have an exact present form, as "Linnaean taxonomy" as such does not really exist: it is a collective (abstracting) term for what actually are several separate fields, which use similar approaches.

St James' Church, Sydney

St James' Church, Sydney

St James' Church, commonly known as St James', King Street, is an Australian heritage-listed Anglican parish church located at 173 King Street, in the Sydney central business district in New South Wales. Consecrated in February 1824 and named in honour of St James the Great, it became a parish church in 1835. Designed in the style of a Georgian town church by the transported convict architect Francis Greenway during the governorship of Lachlan Macquarie, St James' is part of the historical precinct of Macquarie Street which includes other early colonial era buildings such as the World Heritage listed Hyde Park Barracks.

Chancel

Chancel

In church architecture, the chancel is the space around the altar, including the choir and the sanctuary, at the liturgical east end of a traditional Christian church building. It may terminate in an apse.

Augustine of Hippo

Augustine of Hippo

Augustine of Hippo, also known as Saint Augustine, was a theologian and philosopher of Berber origin and the bishop of Hippo Regius in Numidia, Roman North Africa. His writings influenced the development of Western philosophy and Western Christianity, and he is viewed as one of the most important Church Fathers of the Latin Church in the Patristic Period. His many important works include The City of God, On Christian Doctrine, and Confessions.

Trinity

Trinity

The Christian doctrine of the Trinity is the central doctrine concerning the nature of God in most Christian churches, which defines one God existing in three coequal, coeternal, consubstantial divine persons: God the Father, God the Son and God the Holy Spirit, three distinct persons sharing one homoousion (essence) As the Fourth Lateran Council declared, it is the Father who begets, the Son who is begotten, and the Holy Spirit who proceeds. In this context, the three persons define who God is, while the one essence defines what God is. This expresses at once their distinction and their indissoluble unity. Thus, the entire process of creation and grace is viewed as a single shared action of the three divine persons, in which each person manifests the attributes unique to them in the Trinity, thereby proving that everything comes "from the Father," "through the Son," and "in the Holy Spirit."