120-662: Lyme Bay is an area of the English Channel off the south coast of England. The south western counties of Devon and Dorset front onto the bay. The exact definitions of the bay vary. The eastern boundary is usually taken to be Portland Bill on the Isle of Portland , but there is no consensus over the western boundary. The broadest definition places the boundary at Start Point , and therefore includes Tor Bay and Start Bay as areas within Lyme Bay. A narrow definition gives
240-694: A calque , such as Canale della Manica in Italian or the Ärmelkanal in German, or a direct borrowing , such as Canal de la Mancha in Spanish. The International Hydrographic Organization defines the limits of the English Channel as: The Strait of Dover (French: Pas de Calais ), at the Channel's eastern end, is its narrowest point, while its widest point lies between Lyme Bay and
360-543: A 25 kilometres (16 mi) stretch of light steel netting called the Dover Barrage , which it was hoped would ensnare submerged submarines. After initial success, the Germans learned how to pass through the barrage, aided by the unreliability of British mines. On 31 January 1917, the Germans resumed unrestricted submarine warfare leading to dire Admiralty predictions that submarines would defeat Britain by November,
480-453: 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. 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
600-481: A given animal is "facing" requires detailed information about its valves. 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. These ears may be of similar size and shape, or
720-482: A handful of locations. The Lyme Bay supports one of the densest populations found around the UK and also the easternmost population known in UK waters. The reefs have been under threat from scallop dredging which, if unregulated, might destroy the coral's habitat. Devon Wildlife Trust has been campaigning to protect the reefs, calling for an end to the dredging and trawling within a 60-square-mile (160 km) zone to help
840-510: A less pronounced bloom in late summer. Thus underwater visibility rarely exceeds 10 metres (30 ft) and frequently may be less than 3 metres (10 ft). The reefs in the bay, numerous in the centre and east, are mostly discontinuous, forming a patchwork of low rocky outcrops surrounded by sediment. This means that they tend to be covered by thin veneers of sediment as tide and wave action lifts and sweeps saltating sand across them. The amount of sand will vary, depending on
960-526: A physical barrier around byssal openings to prevent sea stars from inserting their digestive membranes. 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. In fact, barnacle encrustation negatively influences swimming in C. hastata . Those swimming with barnacle encrustation require more energy and show
1080-529: A popular object to collect among beachcombers and vacationers. The shells also have a significant place in popular culture. 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
1200-513: A protected World Heritage Site coastline. The ship had been damaged and was en route to Portland Harbour . The English Channel, despite being a busy shipping lane, remains in part a haven for wildlife. Atlantic oceanic species are more common in the westernmost parts of the channel, particularly to the west of Start Point, Devon , but can sometimes be found further east towards Dorset and the Isle of Wight. Seal sightings are becoming more common along
1320-453: A riot of colour nor very clear water. The reefs in Lyme bay are mostly low lying and the waters tend to be fairly gloomy and turbid. As an essentially large, open, sandy bay exposed to the prevailing winds, much suspended sediment (at least near-shore, close to the seabed) exists. Whilst winds may ease in summer, it is also prone to strong plankton blooms during May and June, with
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#17327651526881440-401: 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
1560-586: A similar latitude. The reason for this is the warming action of the Gulf Stream . The area along the coast of Lyme Bay is thus a popular holiday destination. On 22 March 1993, four schoolchildren died in what is known as the Lyme Bay kayaking tragedy . Lyme Bay was the site of Exercise Tiger , a practice run for the D-Day invasion of France in 1944, using the beach called Slapton Sands near Slapton, Devon as
1680-557: 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. Physiological fitness and exercise of scallops decrease with age due to the decline of cellular and especially mitochondrial function, 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
1800-456: 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. 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
1920-514: Is a characteristic that has evolved within the lineage. 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. There have been a number of efforts to address phylogenetic studies. Only three have assessed more than ten species and only one has included multiple outgroups. Nearly all previous molecular analyses of
2040-514: Is a nationally protected species that occurs in very high densities on some of the limestone reefs in Lyme Bay. Reefs in the Eastern part of Lyme Bay support a population of sunset corals ( Leptopsammia pruvoti ). Sunset corals are one of the very few species of true corals (i.e. stony, or scleractinian, corals found in British waters. Sunset corals are rare in British waters, known to occur at only
2160-527: Is also known as the Jurassic Coast , named for its Jurassic geology . Many of the earliest discoveries of dinosaur and other prehistoric reptile remains were in the area surrounding Lyme Regis and Charmouth . Notable among these were the discoveries made by self-educated palaeontologist and fossil collector Mary Anning , in the 1820s. The weather in the bay is temperate by English standards, and far more temperate than many other places at
2280-526: 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. Palliolinae (in part) [REDACTED] Palliolinae (in part) and Camptonectinae Chlamydinae [REDACTED] (70 mya) Pecten [REDACTED] Flexopecten [REDACTED] (247 mya) Aequipecten [REDACTED] Limidae (file shells) [REDACTED] other Pteriomorphia ( oysters , mussels ) [REDACTED] Scallops are
2400-479: 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
2520-639: Is found in modern scallops only; both putative ancestors of modern scallops, the entoliids and the Aviculopectinidae, did not possess it. 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,
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#17327651526882640-495: 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; in terms of diversity, it has been a thriving family to the present day. 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
2760-408: Is open to some debate). Other scallops can extend their foot from between their valves, and by contracting the muscles in their foot, they can burrow into sand. 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
2880-411: 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 . 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. Some level of taxonomic stability
3000-537: Is the busiest shipping area in the world. It is about 560 kilometres (300 nautical miles; 350 statute miles) long and varies in width from 240 km (130 nmi; 150 mi) at its widest to 34 km (18 nmi; 21 mi) at its narrowest in the Strait of Dover . It is the smallest of the shallow seas around the continental shelf of Europe, covering an area of some 75,000 square kilometres (22,000 square nautical miles; 29,000 square miles). The Channel aided
3120-460: The Battle of Britain featured German air attacks on Channel shipping and ports; despite these early successes against shipping the Germans did not win the air supremacy necessary for Operation Sealion , the projected cross-Channel invasion. The Channel subsequently became the stage for an intensive coastal war, featuring submarines, minesweepers , and Fast Attack Craft . The narrow waters of
3240-661: The Glorious Revolution of 1688, while the concentration of excellent harbours in the Western Channel on Britain's south coast made possible the largest amphibious invasion in history, the Normandy Landings in 1944. Channel naval battles include the Battle of the Downs (1639), Battle of Dover (1652), the Battle of Portland (1653) and the Battle of La Hougue (1692). In more peaceful times,
3360-586: The Neolithic front in southern Europe to the Mesolithic peoples of northern Europe." The Ferriby Boats , Hanson Log Boats and the later Dover Bronze Age Boat could carry a substantial cross-Channel cargo. Diodorus Siculus and Pliny both suggest trade between the rebel Celtic tribes of Armorica and Iron Age Britain flourished. In 55 BC Julius Caesar invaded, claiming that the Britons had aided
3480-558: The Norman Conquest beginning with the Battle of Hastings , while retaining the fiefdom of Normandy for himself and his descendants. In 1204, during the reign of King John , mainland Normandy was taken from England by France under Philip II , while insular Normandy (the Channel Islands ) remained under English control. In 1259, Henry III of England recognised the legality of French possession of mainland Normandy under
3600-788: The North Sea to the Western Atlantic via the Strait of Dover is of geologically recent origin, having formed late in the Pleistocene period. The English Channel first developed as an arm of the Atlantic Ocean during the Pliocene period (5.3-2.6 million years ago) as a result of differential tectonic uplift along pre-existing tectonic weaknesses during the Oligocene and Miocene periods. During this early period,
3720-705: The Treaty of Paris . His successors, however, often fought to regain control of mainland Normandy. With the rise of William the Conqueror , the North Sea and Channel began to lose some of their importance. The new order oriented most of England and Scandinavia's trade south, toward the Mediterranean and the Orient. Although the British surrendered claims to mainland Normandy and other French possessions in 1801,
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3840-491: The Treaty of Paris of 1259 , the surrender of French possessions in 1801, and the belief that the rights of succession to that title are subject to Salic Law which excludes inheritance through female heirs. French Normandy was occupied by English forces during the Hundred Years' War in 1346–1360 and again in 1415–1450. From the reign of Elizabeth I , English foreign policy concentrated on preventing invasion across
3960-614: The United Kingdom in becoming a naval superpower, serving as a natural defence to halt attempted invasions, such as in the Napoleonic Wars and in the Second World War . The northern, English coast of the Channel is more populous than the southern, French coast. The major languages spoken in this region are English and French . Roman sources as Oceanus Britannicus (or Mare Britannicum , meaning
4080-652: The Veneti against him the previous year. He was more successful in 54 BC , but Britain was not fully established as part of the Roman Empire until Aulus Plautius 's 43 AD invasion . A brisk and regular trade began between ports in Roman Gaul and those in Britain. This traffic continued until the end of Roman rule in Britain in 410 AD, after which the early Anglo-Saxons left less clear historical records. In
4200-414: The adductor muscle , that is sold as seafood . The brightly coloured, symmetric, fan-shaped shells of scallops with their radiating and often fluted ornamentation are valued by shell collectors, and have been used since ancient times as motifs in art, architecture, and design. Owing to their widespread distribution, scallop shells are a common sight on beaches and are often brightly coloured, making them
4320-412: The heterokonts and dinoflagellates . 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, camouflages Chlamys hastata from predators, or forms
4440-537: The taxonomic family Pectinidae , the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related families within the superfamily Pectinoidea , which also includes the thorny oysters . Scallops are a cosmopolitan family of bivalves found in all of the world's oceans, although never in fresh water. They are one of the very few groups of bivalves to be primarily "free-living", with many species capable of rapidly swimming short distances and even migrating some distance across
4560-615: The 17th century. The name is usually said to refer to the sleeve (French: la manche ) shape of the Channel. Folk etymology has derived it from a Celtic word meaning 'channel' that is also the source of the name for the Minch in Scotland, but this name is not attested before the 17th century, and French and British sources of that time are clear about its etymology. The name in French has been directly adapted in other languages as either
4680-465: The Atlantic. The flooding destroyed the ridge that connected Britain to continental Europe , although a land connection across the southern North Sea would have existed intermittently at later times when periods of glaciation resulted in lowering of sea levels. During interglacial periods (when sea levels were high) between the initial flooding 450,000 years ago until around 180,000 years ago,
4800-590: The Channel by ensuring no major European power controlled the potential Dutch and Flemish invasion ports. Her climb to the pre-eminent sea power of the world began in 1588 as the attempted invasion of the Spanish Armada was defeated by the combination of outstanding naval tactics by the English and the Dutch under command of Charles Howard, 1st Earl of Nottingham with Sir Francis Drake second in command, and
4920-532: The Channel did not connect to the North Sea, with Britain and Ireland remaining part of continental Europe , linked by an unbroken Weald–Artois anticline , a ridge running between the Dover and Calais regions. During Pleistocene glacial periods this ridge acted as a natural dam holding back a large freshwater pro-glacial lake in the Doggerland region, now submerged under the North Sea . During this period,
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5040-455: The Channel for several weeks, but was thwarted following the British naval victory at the Battle of Quiberon Bay in 1759 and was unsuccessful (The last French landing on English soil being in 1690 with a raid on Teignmouth, although the last French raid on British soil was a raid on Fishguard, Wales in 1797). Another significant challenge to British domination of the seas came during the Napoleonic Wars . The Battle of Trafalgar took place off
5160-670: The Channel served as a link joining shared cultures and political structures, particularly the huge Angevin Empire from 1135 to 1217. For nearly a thousand years, the Channel also provided a link between the Modern Celtic regions and languages of Cornwall and Brittany . Brittany was founded by Britons who fled Cornwall and Devon after Anglo-Saxon encroachment. In Brittany, there is a region known as " Cornouaille " (Cornwall) in French and "Kernev" in Breton . In ancient times there
5280-791: The Channel were considered too dangerous for major warships until the Normandy Landings with the exception, for the German Kriegsmarine , of the Channel Dash (Operation Cerberus) in February 1942, and this required the support of the Luftwaffe in Operation Thunderbolt . Scallop See text Pectenidae Scallop ( / ˈ s k ɒ l ə p , ˈ s k æ l ə p / ) is a common name that encompasses various species of marine bivalve mollusks in
5400-598: The Channel would still have been separated from the North Sea by a landbridge to the north of the Strait of Dover (the Strait of Dover at this time formed part of a estuary fed by the Thames and Scheldt ), restricting interchange of marine fauna between the Channel and the North Sea (except perhaps by occasional overtopping). During the Last Interglacial/Eemian (115–130,000 years ago) the connection between
5520-608: The English Channel, with both Grey Seal and Harbour Seal recorded frequently. The Channel is thought to have prevented Neanderthals from colonising Britain during the Last Interglacial/Eemian, though they returned to Britain during the Last Glacial Period when sea levels were lower. The Channel has in historic times been both an easy entry for seafaring people and a key natural defence, halting invading armies while in conjunction with control of
5640-520: The English coast, and the Channel Islands , British Crown Dependencies off the coast of France. The coastline, particularly on the French shore, is deeply indented, with several small islands close to the coastline, including Chausey and Mont-Saint-Michel . The Cotentin Peninsula on the French coast juts out into the Channel, with the wide Bay of the Seine (French: Baie de Seine ) to its east. On
5760-601: The English side there is a small parallel strait , the Solent , between the Isle of Wight and the mainland. The Celtic Sea is to the west of the Channel. The Channel acts as a funnel that amplifies the tidal range from less than a metre at sea in eastern places to more than 6 metres in the Channel Islands , the west coast of the Cotentin Peninsula and the north coast of Brittany in monthly spring tides . The time difference of about six hours between high water at
5880-586: The Gulf of Saint Malo , near its midpoint. Well on the continental shelf, it has an average depth of about 120 m (390 ft) at its widest; yet averages about 45 m (148 ft) between Dover and Calais , its notable sandbank hazard being Goodwin Sands . Eastwards from there the adjoining North Sea reduces to about 26 m (85 ft) across the Broad Fourteens (14 fathoms) where it lies over
6000-451: The North Sea allowing Britain to blockade the continent. The most significant failed invasion threats came when the Dutch and Belgian ports were held by a major continental power, e.g. from the Spanish Armada in 1588, Napoleon during the Napoleonic Wars , and Nazi Germany during World War II . Successful invasions include the Roman conquest of Britain , the Norman Conquest in 1066 and
6120-579: The North Sea and almost all of the British Isles were covered by ice. The lake was fed by meltwater from the Baltic and from the Caledonian and Scandinavian ice sheets that joined to the north, blocking its exit. The sea level was about 120 m (390 ft) lower than it is today. Then, between 450,000 and 180,000 years ago, at least two catastrophic glacial lake outburst floods breached
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#17327651526886240-543: The North Sea and the English Channel was fully open as it is today, resulting in Britain being an island during this interval, before lowered sea levels reconnected it to the continent during the Last Glacial Period . From the end of the Last Glacial Period, to the beginning of the Holocene rising sea levels again resulted in the unimpeded connection between the North Sea and the English Channel resuming due to
6360-604: The Ocean, or the Sea, of the Britons or Britannī ). Variations of this term were used by influential writers such as Ptolemy , and remained popular with British and continental authors well into the modern era. Other Latin names for the sea include Oceanus Gallicus (the Gaulish Ocean) which was used by Isidore of Seville in the sixth century. The term British Sea is still used by speakers of Cornish and Breton , with
6480-663: 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. In molecular phylogenies of the Bivalvia, both the Spondylidae and the Propeamussiidae have been resolved as sister to
6600-459: The Pectinidae. The following are recognised in the family Pectinidae: 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). In
6720-539: The Weald–Artois anticline. These contributed to creating some of the deepest parts of the channel such as Hurd's Deep . The first flood of 450,000 years ago would have lasted for several months, releasing as much as one million cubic metres of water per second. The flood started with large but localised waterfalls over the ridge, which excavated depressions now known as the Fosses Dangeard . The flow eroded
6840-581: 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. The cladogram
6960-538: The amount of glycogen stored in muscle tissue. Environmental factors, such as changes in oxidative stress parameters, can inhibit the growth and development of scallops. 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
7080-409: The anatomy of any given scallop species. The shell of a scallop consists of two sides or valves , a left valve and a right one, divided by a plane of symmetry . 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
7200-455: 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. Scallops have a large number (up to 200) of small (about 1 mm) eyes arranged along
7320-428: 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
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#17327651526887440-434: The beginning of the Viking Age . For the next 250 years the Scandinavian raiders of Norway, Sweden, and Denmark dominated the North Sea, raiding monasteries, homes, and towns along the coast and along the rivers that ran inland. According to the Anglo-Saxon Chronicle they began to settle in Britain in 851. They continued to settle in the British Isles and the continent until around 1050, with some raids recorded along
7560-633: 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 ). 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
7680-401: The centre of the Straits of Dover and into the English Channel. It left streamlined islands, longitudinal erosional grooves, and other features characteristic of catastrophic megaflood events, still present on the sea floor and now revealed by high-resolution sonar. Through the scoured channel passed a river, the Channel River , which drained the combined Rhine and Thames westwards to
7800-439: The channel coast of England, including at Wareham, Portland, near Weymouth and along the river Teign in Devon. The fiefdom of Normandy was created for the Viking leader Rollo (also known as Robert of Normandy). Rollo had besieged Paris but in 911 entered vassalage to the king of the West Franks Charles the Simple through the Treaty of St.-Claire-sur-Epte . In exchange for his homage and fealty , Rollo legally gained
7920-408: The coast of Spain against a combined French and Spanish fleet and was won by Admiral Horatio Nelson , ending Napoleon 's plans for a cross-Channel invasion and securing British dominance of the seas for over a century. The exceptional strategic importance of the Channel as a tool for blockading was recognised by the First Sea Lord Admiral Fisher in the years before World War I . "Five keys lock up
8040-485: 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. 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
8160-570: The concentric rings of their shells. 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
8280-406: 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
8400-434: The eastern and western limits of the Channel is indicative of the tidal range being amplified further by resonance . Amphidromic points are the Bay of Biscay and varying more in precise location in the far south of the North Sea, meaning both those associated eastern coasts repel the tides effectively, leaving the Strait of Dover as every six hours the natural bottleneck short of its consequent gravity-induced repulsion of
8520-423: The eastern boundary as Hope's Nose headland, excluding Tor Bay and Start Bay, used for example by the Water Framework Directive definitions of waterbodies. Other definitions place the boundary somewhere between these two points, including at Dartmouth (used by the Lyme Bay West Marine Character Area ) and Berry Head . The east of the bay is part of a World Heritage Site , the Dorset and East Devon Coast, which
8640-444: 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. Additionally, their eyes possess a double-layered retina, the outer retina responding most strongly to light and the inner to abrupt darkness. While these eyes are unable to resolve shapes with high fidelity,
8760-570: The end of the war and the project was abandoned. The naval blockade in the Channel and North Sea was one of the decisive factors in the German defeat in 1918. During the Second World War , naval activity in the European theatre was primarily limited to the Atlantic . During the Battle of France in May 1940, the German forces succeeded in capturing both Boulogne and Calais , thereby threatening
8880-412: The family Pectinidae is monophyletic, developing from a single common ancestor. The direct ancestors of Pectinidae were scallop-like bivalves of the family Entoliidae. 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
9000-420: 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
9120-634: The following stormy weather. Over the centuries the Royal Navy slowly grew to be the most powerful in the world. The building of the British Empire was possible only because the Royal Navy eventually managed to exercise unquestioned control over the seas around Europe, especially the Channel and the North Sea. During the Seven Years' War , France attempted to launch an invasion of Britain . To achieve this France needed to gain control of
9240-412: 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. Like all bivalves, scallops lack actual brains. Instead, their nervous system
9360-518: The frontier of Switzerland to the English Channel", they reached the coast at the North Sea. Much of the British war effort in Flanders was a bloody but successful strategy to prevent the Germans reaching the Channel coast. At the outset of the war, an attempt was made to block the path of U-boats through the Dover Strait with naval minefields . By February 1915, this had been augmented by
9480-500: 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. Raines and Poppe 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
9600-686: The line of retreat for the British Expeditionary Force . By a combination of hard fighting and German indecision, the port of Dunkirk was kept open allowing 338,000 Allied troops to be evacuated in Operation Dynamo . More than 11,000 were evacuated from Le Havre during Operation Cycle and a further 192,000 were evacuated from ports further down the coast in Operation Aerial in June 1940. The early stages of
9720-723: The monarch of the United Kingdom retains the title Duke of Normandy in respect to the Channel Islands. The Channel Islands (except for Chausey ) are Crown Dependencies of the British Crown . Thus the Loyal toast in the Channel Islands is Le roi, notre Duc ("The King, our Duke"). The British monarch is understood to not be the Duke of Normandy in regards of the French region of Normandy described herein, by virtue of
9840-703: The most dangerous situation Britain faced in either world war. The Battle of Passchendaele in 1917 was fought to reduce the threat by capturing the submarine bases on the Belgian coast, though it was the introduction of convoys and not capture of the bases that averted defeat. In April 1918 the Dover Patrol carried out the Zeebrugge Raid against the U-boat bases. During 1917, the Dover Barrage
9960-502: 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. Scallops are highly sensitive to shadows, vibrations, water movement, and chemical stimuli. 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
10080-577: The name was popularly understood by English people. By the eighteenth century, the name English Channel was in common usage in England . Following the Acts of Union 1707 , this was replaced in official maps and documents with British Channel or British Sea for much of the next century. However, the term English Channel remained popular and was finally in official usage by the nineteenth century. The French name la Manche has been used since at least
10200-409: 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. The visceral ganglia are also the origin of the branchial nerves which control the scallop's gills. The cerebral ganglia are
10320-407: 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
10440-494: The northwest of Portland in the UK's shipping forecast . 50°42′N 2°54′W / 50.700°N 2.900°W / 50.700; -2.900 English Channel The English Channel , also known as the Channel , is an arm of the Atlantic Ocean that separates Southern England from northern France . It links to the southern part of the North Sea by the Strait of Dover at its northeastern end. It
10560-533: 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. The lifespans of some scallops have been known to extend over 20 years. Scallops are known to be infected by viruses , bacteria , microalgae of
10680-480: The ocean floor. A small minority of scallop species live cemented to rocky substrates as adults, while others attach themselves to stationary or rooted objects such as seagrass at some point in their lives by means of a filament they secrete called a byssal thread . The majority of species, however, live recumbent on sandy substrates, and when they sense the presence of a predator such as a starfish , they may attempt to escape by swimming swiftly but erratically through
10800-593: The power vacuum left by the retreating Romans, the Germanic Angles , Saxons , and Jutes began the next great migration across the North Sea. Having already been used as mercenaries in Britain by the Romans, many people from these tribes crossed during the Migration Period , conquering and perhaps displacing the native Celtic populations. The attack on Lindisfarne in 793 is generally considered
10920-511: The practice landing zone. The operation was intercepted by German E-boats that attacked the landing craft, killing 749 American Army and Navy personnel in the middle of Babbacombe Bay , the most unbounded western sub-bay of the bay. A ship commissioned in 2007 for the Royal Fleet Auxiliary carries the name: RFA Lyme Bay . Much of the subsurface realm is locally unspectacular, without underwater rock cliffs painted with
11040-779: The reefs recover. About 20% of this area is now protected by a voluntary agreement made between the DEFRA and the fishermen of the South West Inshore Fishermen's Association. Towns and villages marked * fall outside some of the narrower definitions of Lyme Bay. Rivers that flow into Lyme Bay include the Exe , Otter , Teign , Dart , Sid and Axe in Devon, and the Lim , Char , Brit and Bride in Dorset. The whole bay forms
11160-541: The retaining ridge, causing the rock dam to fail and releasing lake water into the Atlantic. After multiple episodes of changing sea level, during which the Fosses Dangeard were largely infilled by various layers of sediment, another catastrophic flood some 180,000 years ago carved a large bedrock-floored valley, the Lobourg Channel , some 500 m wide and 25 m deep, from the southern North Sea basin through
11280-474: 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
11400-555: The sea as Sūð-sǣ (South Sea), but this term fell out of favour, as later English authors followed the same conventions as their Latin and Norman contemporaries. One English name that did persist was the Narrow Seas , a collective term for the channel and North Sea . As England (followed by Great Britain and the United Kingdom) claimed sovereignty over the sea, a Royal Navy Admiral was appointed with maintaining duties in
11520-535: The sea as Britanicus Oceanus nunc Canalites Anglie (Ocean of the Britons but now English Channel). The map is possibly the first recorded use of the term English Channel and the description suggests the name had recently been adopted. In the sixteenth century, Dutch maps referred to the sea as the Engelse Kanaal (English Channel) and by the 1590s, William Shakespeare used the word Channel in his history plays of Henry VI , suggesting that by that time,
11640-409: 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). Both jumping and swimming movements are very energy-intensive, and most scallops cannot perform more than four or five in
11760-525: The sea known to them as Mor Bretannek and Mor Breizh respectively. While it is likely that these names derive from the Latin term, it is possible that they predate the arrival of the Romans in the area. The modern Welsh is often given as Môr Udd (the Lord's or Prince's Sea); however, this name originally described both the Channel and the North Sea combined. Anglo-Saxon texts make reference to
11880-474: 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
12000-412: The shell shape tends to be highly regular, and is commonly used as an archetypal form of a seashell . 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
12120-565: The shell which is situated next to the byssal notch. 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. 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. Fossil records also indicate that
12240-502: The sinking of Doggerland , with Britain again becoming an island. As a busy shipping lane, the Channel experiences environmental problems following accidents involving ships with toxic cargo and oil spills. Indeed, over 40% of the UK incidents threatening pollution occur in or very near the Channel. One occurrence was the MSC Napoli , which on 18 January 2007 was beached with nearly 1700 tonnes of dangerous cargo in Lyme Bay,
12360-537: The size of the reef, how high it rises above the surrounding sediment plain, the strength of tidal streams in that part of the bay and how strong the wind has been recently (and thus how big the waves). Conversely the reef ecosystems are different from clearer water reefs further west. Tank wrecks from the D-Day practice provide a venue for diving . Marine life includes the Devon cup coral ( Caryophyllia smithii ) and pink sea fan ( Eunicella verrucosa ) . The pink seafan
12480-401: The smooth catch adductor muscle lacks striations, and contracts for long periods, keeping shells closed with little expenditure of energy. 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,
12600-475: The southern cusp of the former land bridge between East Anglia and the Low Countries . The North Sea reaches much greater depths east of northern Britain. The Channel descends briefly to 180 m (590 ft) in the submerged valley of Hurd's Deep , 48 km (30 mi) west-northwest of Guernsey . There are several major islands in the Channel, the most notable being the Isle of Wight off
12720-620: The southward tide (surge) of the North Sea (equally from the Atlantic). The Channel does not experience, but its existence is necessary to explain the extent of North Sea storm surges , such as necessitate the Thames Barrier , Delta Works , Zuiderzee works ( Afsluitdijk and other dams). In the UK Shipping Forecast the Channel is divided into the following areas, from the east: The full English Channel connecting
12840-570: The territory he and his Viking allies had previously conquered. The name "Normandy" reflects Rollo's Viking (i.e. "Northman") origins. The descendants of Rollo and his followers adopted the local Gallo-Romance language and intermarried with the area's inhabitants and became the Normans – a Norman French -speaking mixture of Scandinavians , Hiberno-Norse , Orcadians , Anglo-Danish , and indigenous Franks and Gauls . Rollo's descendant William, Duke of Normandy became king of England in 1066 in
12960-404: 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. However, as many scallop shells are more or less bilaterally symmetrical ("equivalved"), as well as symmetrical front/back ("equilateral"), determining which way
13080-399: The turbidity or clarity of the water, by detecting the movement of particulate matter in the water column. 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
13200-569: The two seas. The office was maintained until 1822, when several European nations (including the United Kingdom) adopted a three-mile (4.8 km) limit to territorial waters. The word channel was first recorded in Middle English in the 13th century and was borrowed from the Old French word chanel (a variant form of chenel 'canal'). By the middle of the fifteenth century, an Italian map based on Ptolemy 's description named
13320-426: 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. 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
13440-503: 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 ,
13560-425: The water using jet propulsion created by repeatedly clapping their shells together. Scallops have a well-developed nervous system, and unlike most other bivalves all scallops have a ring of numerous simple eyes situated around the edge of their mantles . Many species of scallops are highly prized as a food source, and some are farmed as aquaculture . The word "scallop" is also applied to the meat of these bivalves,
13680-514: The water. Spawning typically occurs in late summer and early autumn; spring spawning may also take place in the Mid-Atlantic Bight . The females of scallops are highly fecund, capable of producing hundreds of millions of eggs per year. 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
13800-635: The world! Singapore, the Cape, Alexandria , Gibraltar, Dover." However, on 25 July 1909 Louis Blériot made the first Channel crossing from Calais to Dover in an aeroplane. Blériot's crossing signalled a change in the function of the Channel as a barrier-moat for England against foreign enemies. Because the Kaiserliche Marine surface fleet could not match the British Grand Fleet, the Germans developed submarine warfare , which
13920-477: The year. This phenomenon is due to lower protein levels in adductor muscles. 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). Female scallops have red roe and male scallops have white roe. Spermatozoa and ova are released freely into
14040-476: 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. The framework of its phylogeny shows that repeated life habit states derive from evolutionary convergence and parallelism. Studies have determined
14160-459: Was also a " Domnonia " (Devon) in Brittany as well. In February 1684 , ice formed on the sea in a belt 4.8 km (3.0 mi) wide off the coast of Kent and 3.2 km (2.0 mi) wide on the French side. Remnants of a mesolithic boatyard have been found on the Isle of Wight . Wheat was traded across the Channel about 8,000 years ago. "... Sophisticated social networks linked
14280-495: Was re-sited with improved mines and more effective nets, aided by regular patrols by small warships equipped with powerful searchlights. A German attack on these vessels resulted in the Battle of Dover Strait in 1917 . A much more ambitious attempt to improve the barrage, by installing eight massive concrete towers across the strait was called the Admiralty M-N Scheme but only two towers were nearing completion at
14400-486: Was to become a far greater threat to Britain. The Dover Patrol , set up just before the war started, escorted cross-Channel troopships and prevented submarines from sailing in the Channel, obliging them to travel to the Atlantic via the much longer route around Scotland. On land, the German army attempted to capture French Channel ports in the Race to the Sea but although the trenches are often said to have stretched "from
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