Demersal fish live and feed on or near the bottom of seas or lakes. They occupy the sea floors and lake beds, which consist of mud, gravel or rocks. In coastal waters they are found on or near the continental shelf, in deep waters they are found on or near the continental slope or along the continental rise, they are not found in the deepest waters, such as abyssal depths or on the abyssal plain, but they can be found around seamounts and islands. The word demersal comes from the Latin demergere. Demersal fish are bottom feeders, they can be contrasted with pelagic fish which live and feed away from the bottom in the open water column. Demersal fish fillets contain little fish oil. Demersal fish can be divided into two main types: benthic fish which can rest on the sea floor, benthopelagic fish which can float in the water column just above the sea floor. Benthopelagic fish have neutral buoyancy, so they can float at depth without much effort, while benthic fish are denser, with negative buoyancy so they can lie on the bottom without any effort.
Most demersal fish are benthopelagic. As with other bottom feeders, a mechanism to deal with substrate is necessary. With demersal fish the sand is pumped out of the mouth through the gill slit. Most demersal fish exhibit a flat ventral region so as to more rest their body on the substrate; the exception may be the flatfish, which lie on their sides. Many exhibit what is termed an "inferior" mouth, which means that the mouth is pointed downwards; those bottom feeders with upward-pointing mouths, such as stargazers, tend to seize swimming prey. Benthic fish, sometimes called groundfish, are denser than water, so they can rest on the sea floor, they either lie-and-wait as ambush predators, maybe covering themselves with sand or otherwise camouflaging themselves, or move over the bottom in search for food. Benthic fish which can bury themselves include dragonets and stingrays. Flatfish are an order of ray-finned benthic fishes. Examples are flounder, turbot and halibut; the adult fish of many species have both eyes on one side of the head.
When the fish hatches, one eye is located on each side of its head. But as the fish grows from the larval stage, one eye migrates to the other side of the body as a process of metamorphosis; the flatfish changes its habits, camouflages itself by lying on the bottom of the ocean floor with both eyes facing upwards. The side to which one eye migrates depends on the species. Flounder ambush their prey, feeding at soft muddy area of the sea bottom, near bridge piles, docks and coral reefs, their diet consists of fish spawn, crustaceans and small fish. The great hammerhead swings its head in broad angles over the sea floor to pick up the electrical signatures of stingrays buried in the sand, it uses its "hammer" to pin down the stingray. Some fishes don't fit into the above classification. For example, the family of nearly blind spiderfishes and distributed, feed on benthopelagic zooplankton, yet they are benthic fish, since they stay in contact with the bottom. Their fins have long rays they use to "stand" on the bottom while they face the current and grab zooplankton as it passes by.
The bodies of benthic fish are adapted for ongoing contact with the sea floor. Swimbladders are absent or reduced, the bodies are flattened in one way or another. Following Moyle and Cech they can be divided into five overlapping body shapes: Benthopelagic fish inhabit the water just above the bottom, feeding on benthos and zooplankton. Most demersal fish are benthopelagic. Deep sea benthopelagic teleosts all have swimbladders; the dominant species and cusk eels, have considerable biomass. Other species include deep sea cods, deep sea eels and notacanths. Benthopelagic sharks, like the deep sea squaloid sharks, achieve neutral buoyancy with the use of large oil-filled livers. Sharks adapt well to high pressures, they can be found on slopes down to about 2000 metres, scavenging on food falls such as dead whales. However, the energy demands of sharks are high, since they need to swim and maintain a large amount of oil for buoyancy; these energy needs can not be met in the extreme oligotrophic conditions.
Shallow water stingrays are benthic, can lie on the bottom because of their negative buoyancy. Deep sea stingrays are benthopelagic, like the squaloids have large livers which give them neutral buoyancy. Benthopelagic fish can be divided into flabby or robust body types. Flabby benthopelagic fishes are like bathypelagic fishes. An example of a flabby fish is the cusk-eel Acanthonus armatus, a predator with a huge head and a body, 90 percent water; this fish has the largest ears and the smallest brain in relation to its body size of all known vertebrates. Deepwater benthopelagic fish are robust, muscular swimmers that cruise the bottom searching for prey, they live around features, such as seamounts, which have strong currents. Commercial examples are Patagonian toothfish; the edge of the continental shelf marks the boundary where the shelf gives way to, gradually drops into abyssal depths. This edge marks the bound
Paralichthys lethostigma, the southern flounder, is a species of large-tooth flounders native to the eastern and gulf coasts of the United States. It is a popular sports fish and is the largest and most commercially valuable flounder in the western North Atlantic Ocean and Gulf of Mexico, it is a "left-eyed flounder", meaning the left side is pigmented and is the "up side". The body color is brown with unocellated spots and blotches; this species grows to around 12-14 inches in length. Larval and postlarval southern flounder feed on zooplankton; as juveniles, the southern flounder’s diet consists of small invertebrates, shifts to larger invertebrates and fish as they reach adult size. Southern flounder feed on the bottom of the ocean and in the water column, are considered to be near top predators. Adult fish breed and spend the warmer season in coastal embayments and nearshore shelf waters, where the eggs develop until they are late stage larvae, which are pushed by currents into the estuaries where the fish settle into the sediment and grow into juveniles.
The juveniles stay in the estuaries until they leave to spawn. The southern flounder can survive in lower salinities and have been found to use freshwater habitats both as juveniles and as adults. Juvenile southern flounder stay in estuaries, most leave to spawn offshore during the fall and winter as adults. Young fish are pushed into the estuaries by ocean currents to mature. Southern flounder reach sexual maturity around two years of age. Older, larger fish tend to begin the spawning migration earlier. Female fish both grow faster and live longer than males; the annual growth cycle of the southern flounder starts in the spring and ends in the fall as the water temperature decreases. Males live for around 5 years, females live for around 7-8 years; the southern flounder is distributed across the Gulf of Mexico. This species is listed by the IUCN as near threatened due to both commercial and recreational overfishing, mortality from the shrimp trawl industry; this species is affected by habitat destruction from human causes.
Southern flounders are a major and valuable species in the important commercial and recreational flounder fishery in the Gulf of Mexico. Most of the commercial catch in the Gulf of Mexico is incidental to the catch by shrimp trawlers. Recreationally, they can be caught by anglers on a line with either a lure or live bait. Another popular form of collecting flounders is by night gigging. In this sport, anglers use a gig, or a multi-pronged spear, to impale the fish after using a flashlight to spot it in the waters at night. Southern flounder are considered valuable as an aquaculture species because of their ability to live in water of varying salinities. Research has been conducted on using soy based protein sources rather than fish meal to grow the fish to reduce environmental impact; the genus name, Paralichthys, is interpreted as "parallel fish" in reference to the compressed body shape. However, some interpret it as "close to the sea", from the Greek word, meaning beside or near; this can be in reference to the way it buries itself in the sand and lies flat as if it is a part of the sea floor itself.
The species name, comes from the Latin word, meaning death, the Greek word, meaning spots. The meaning "forgotten spots" or "death of spots" refers to the absences of conspicuous large occellaed spots, common in other species of flatfish. Southern flounder, a family of species known as "southern flounders" Flatfish Lefteye flounder, the former family of the southern flounder, Bothidae Paralichthyidae, the current family of the southern flounder FishBase entry for Southern Flounder
Pleuronectidae known as righteye flounders, are a family of flounders. They are called "righteye flounders" because most species lie on the sea bottom on their left sides, with both eyes on their right sides; the Paralichthyidae are the opposite, with their eyes on the left side. A small number of species in Pleuronectidae can have their eyes on the left side, notably the members of the genus Platichthys, their dorsal and anal fins are long and continuous, with the dorsal fin extending forward onto the head. Females lay eggs that float in mid-water until the larvae develop, they sink to the bottom, they are found on the bottoms of oceans around the world, with some species, such as the Atlantic halibut, Hippoglossus hippoglossus, being found down to 2,000 m. The smaller species eat sea-floor invertebrates such as polychaetes and crustaceans, but the larger righteye flounders, such as H. hippoglossus, which grows up to 4.7 m in length, feed on other fishes and cephalopods, as well. They include many important commercially fished species, including not only the various fish called flounders, but the European plaice, the halibuts, the lemon sole, the common dab, the Pacific Dover sole, the flukes.
The name of the family is derived from the Greek πλευρά, meaning "rib" or "side", νηκτόν, meaning "swimming". The family has four subfamilies: Pleuronectinae – 27 genera and about 60 species in the Northern Hemisphere Paralichthodinae – one species off southern Africa Poecilopsettinae – three genera and about 20 species in tropical and subtropical oceans Rhombosoleinae – nine genera and about 20 species in the Southern HemisphereIn some classifications, the last three subfamilies are raised to the level of families. Bothidae, the lefteye family of flounders
Witch (righteye flounder)
Glyptocephalus cynoglossus, known in English by a variety of common names including the witch, witch flounder, pole flounder, craig fluke, Torbay sole and grey sole, is a species of flatfish from the family Pleuronectidae. It occurs on both sides of the North Atlantic Ocean on muddy sea beds in quite deep water. In northern Europe it has some importance in fisheries as a food fish. Glyptocephalus cynoglossus is a right-eyed flatfish with a small mouth which reaches the forward edge of the lower eye; the mouth contains a single series of incisor like teeth. It has a small head which takes up a fifth of the total length with large, open blister-like mucous pits on its blind side Its body is dorsally compressed and oval in shape; the body is elongated and has a standard length, 2.5-3.5 times longer than it is broad. The lateral line is straight and runs the length of its body with 110-140 scales; the dorsal fin has 95-120 rays and the anal fin has 85-102 rays, there is a short, sharp spine pointing forward in front of the anal fin, created by an elongation first interhaemal spine of the post-abdominal bone, although this is sometimes so small that it is hidden.
The pectoral fin on the eyed side is shorter than the head and the pectoral fins are blackish towards their tips. All of the head and body, apart from the tip of the snout and the lower jaw is covered in smooth scales which make the fish slippery when held, they are brownish grey to greyish brown in colour on their eyed side, with less variation in colour than other flatfish, with the body and fins densely spotted with minute black spots. The blind side is white,marked with tiny black dots, although fish are recorded with the blind side a similar colour to the eyed side, they grow to a maximum size of 60cm standard length but are no more than 40cm. Glyptocephalus cynoglossus occurs on both sides of the North Atlantic Ocean. In the northeastern Atlantic Ocean it is found from the northernmost part of the Bay of Biscay to the Kattegat and into the westernmost part of the Baltic Sea, northwards along the entire coast of Norway and east in to the Murmansk region of Russia and west to the southern and western coasts of Iceland.
In the western North Atlantic their range runs from Newfoundland and Labrador south as far as North Carolina, including the Grand Banks, Gulf of Maine, Gulf of St Lawrence and the Scotian Shelf. Glyptocephalus cynoglossus adults are found on the continental shelf and upper continental slope with a preference for fine sediments such as clay, muddy sand, pure mud, they occur where there are deep holes and channels on the continental shelf. They are benthic and occur in deep water, ranging between 45m and 1460m, but at depths between 184m and 366m; this species prefers temperatures of 2-6°C. The juvenile fish cease to be nektonic when they grow to lengths of 5-6 cm and adopt a benthic habit at shallower depths than the adults. Glyptocephalus cynoglossus feeds on invertebrates and in European waters the main prey items are small crustaceans, small molluscs, worms. Fish are taken, if at all, it does not take baits. Spawning occurs between May and September.and can take place in temperatures ranging from near freezing to 8.8-10°C, experiments have demonstrated that the eggs continue to incubate in water, as cold as 7.2C. and as warm as 12.77°C.
The eggs take around a week to hatch, the newly hatched larvae being about 4.9mm in length with a large yolk sac. As the larvae grow they develop five transverse bands on their body, the reduced yolk and the fin folds; the entire yolk is absorbed. At around 40mm the left eye has migrated to the dorsal surface of the head, the migration of the eye is completed at lengths of between 40 to 50 mm. and it is at this point that the young fish adopts a benthic habit. It is a slow growing species, sexual maturity is reached at 3-4 years and they have a lifespan of up to 14 years, although the maximum reported age is 25 years. Off Norway a sex ratio of 1:1 was found for fish up to the age of 9 years but in older fish this was skewed towards females; the fecundity of females varies with size with 48,800 eggs borne by a fish of 31cm in length to 508,300 eggs in one of 60cm. Glyptocephalus cynoglossus is commercially important as a bycatch and there are fisheries directed at this species, except that it is targeted in the Skagerrak.
It is an important bycatch species in some fisheries. There was a notable increase in the landings of this species in the 1980s as a result of increased fishing effort by Iceland and Norway; the North Sea is where most of the commercial landings in the northeast Atlantic are made and this species is landed in Norway. The FAO reported a total catch for G. cynoglossus in 1999 of 18,969 tonnes, while more recent statistics are that 13,600 tonnes are taken by European fisheries annually with United Kingdom vessels taking around 3,600 tonnes of this total catch. In North America commercial fisheries take around 2,700 tonnes annually, they are caught with bottom trawls using techniques known as "demersal bottom trawling" and "small flatfish bottom trawling". The IUCN classifies this species as Least Concern, but the damaging bottom trawling methods used to catch it may cause issues, the large number discarded as bycatch by commercial vessels which are targeting other species is unknown; the flesh is marketed fresh or frozen and is eaten steamed, fried and baked.
The name Torbay sole appears to be a culinary term, following the habit of renaming certain fish to broaden their appeal
The Gulf flounder is a species of saltwater flounder. The Gulf flounder is a flatfish, their two eyes look upward. They have sharp teeth, two eyes on one side, have a white side. Paralichthys albigutta is distributed in the western North Atlantic. Adults are found in a variety of habitats, but prefer hard, sandy bottoms. Longevity is 7 -- 10 females reach maturity between 1 -- 2 years, it is recreationally exploited. The center of abundance of Paralichthys albigutta in the Gulf of Mexico is along the northeastern coast of Florida. West of the Mississippi River delta, it occurs in low numbers, it appears to occur in low abundance in seagrass beds. It is common in museum collections. Many species of fishes, including P. albigutta, have experienced declines in abundance in the Northern Gulf of Mexico from 1970-2000. Gill netting has been implicated in the decline of flounder stocks in North Carolina due to targeting of non-reproductive juveniles, it is found in a variety of habitats, including seagrass beds, coastal lagoons, flat hard-bottom and limestone ledges.
It prefers sandy bottoms. Juveniles utilize are found adjacent to vegetation in estuaries. Juveniles inhabit older adults occur offshore in deeper depths, it undergoes ontogenetic shifts in dietary preference, feeding on amphipods and small crustaceans at small sizes, feeding on fishes as adults. Adults spend most of the year in bays and estuaries, migrating into deeper offshore waters to spawn during fall and winter. Specimens with ripe gonads have been collected at depths of 20–40 m in the eastern Gulf of Mexico. Larvae migrate inshore during January–February; the age at maturity for females is 1 year with all mature by 2 years and size at 50% maturity is 35–38 cm TL. Males reach maturity between 30–35 cm TL. Females grow larger than males. Longevity for males is 8–11 years and females is 7 years, they are a common sport fish that can be caught with dead fish, live bait, or artificial or frozen baits such as shrimp or clams. A common way of catching this flounder is by jigging; the recreational daily bag limit for this species is 10 and the minimum size is 12 inches.
Commercial fishermen are permitted to take up to 50 lbs of flounder species as by-catch per trip. The Gulf States Marine Fisheries Commission is conducting stock assessments for gulf and southern flounder populations in the Gulf of Mexico, which will inform the development of a fishery management plan; this species is recreationally exploited as a foodfish. It is caught using trawl, gill net, hook-and-line, trammel net; as with P. lethostigma, this species is harvested using gill nets in estuaries. Gulf flounder appear to prefer the ocean floor and camouflage against areas to stealthily strike their prey; this demersal species occurs in shallow depths within coastal environments. This is a commercially and recreationally important species in Florida, it is taken as by-catch in commercial trawl fisheries the penaeid shrimp fishery. Seagrass beds have experienced historical declines off Florida in Florida Bay; the large seagrass die-off in Florida Bay between 1987-1995 was caused by salinity stress and algal blooms.
Over that decade, the standing crop of Thalassia testudinum declined by 28%, Halodule wrightii by 92%, Syringodium filiforme by 88%. Since the decline has slowed, but die-off continues to occur. Between 1995-2003, turtle and shoal grass abundance increased with improved water clarity and has remained stable. Tampa Bay and Sarasota Bay experienced significant seagrass declines in the 1980s, but has since recovered following the improvement of waste water management, it has been recorded in the diet of the invasive Lionfish, which occurs throughout the entire depth range of P. albigutta
The peacock flounder known as the flowery flounder, is a species of fish in the family Bothidae. The species is found in shallow waters in the Indo-Pacific ranging into warmer parts of the east Pacific; the peacock flounder is called flowery flounder because it is covered in superficially flower-like bluish spots. As suggested by the family name, lefteye flounders have both eyes on top of the left hand side of their heads; the eyes are raised up on short stumps like radar dishes, can move in any direction independent of each other. That feature provides flounders with a wide range of view. One eye can look forward; the baby flounders have one eye on each side of their bodies like ordinary fish, swim like other fishes do, but on, as they are becoming adult, the right eye moves to the left side, flounders start to swim sideways, which gives them the ability to settle down flat on the bottom. The maximum length of this flounder is about 45 centimetres. Peacock flounders are found in shallow water on sandy bottoms.
Sometimes they rest over piles of bare rock. They may be found as deep as 150 meters; as most flounders, the peacock flounder is nocturnal, but is sometimes active during the day. It hunts for small fishes and shrimp. Peacock flounders breed in early spring. After the female releases two to three million eggs, males fertilize them; the fertilized eggs float close to the surface carried by the currents, hatch in 15 days. Before hatching the eggs sink to the bottom. For the next four to six months baby flounders float in the open ocean, sometimes hundreds of miles from the place the eggs were released and hatched. During those months the right eye of the juvenile moves to the left side. Like all flounders, peacock flounders are masters of camouflage, they use cryptic coloration to avoid being detected by predators. Whenever possible rather than swim they crawl on their fins along the bottom while changing colors and patterns. In a study, peacock flounders demonstrated the ability to change colors in just eight seconds.
They were able to match the pattern of a checkerboard they were placed on. The changing of the colors is an complex and not well understood process, it involves the flounder's vision and hormones. The flounders match the colors of the surface by releasing different pigments to the surface of the skin cells while leaving some of the cells white by suppressing those pigments. If one of the flounder's eyes is damaged or covered by sand, the flounders have difficulties in matching their colors to their surroundings. Whenever hunting or hiding from predators, the flounders bury themselves into the sand leaving only the eyes protruding
Hawaii is the 50th and most recent state to have joined the United States, having received statehood on August 21, 1959. Hawaii is the only U. S. state located in Oceania, the only U. S. state located outside North America, the only one composed of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean; the state encompasses nearly the entire volcanic Hawaiian archipelago, which comprises hundreds of islands spread over 1,500 miles. At the southeastern end of the archipelago, the eight main islands are—in order from northwest to southeast: Niʻihau, Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, Kahoʻolawe and the Island of Hawaiʻi; the last is the largest island in the group. The archipelago is ethnologically part of the Polynesian subregion of Oceania. Hawaii's diverse natural scenery, warm tropical climate, abundance of public beaches, oceanic surroundings, active volcanoes make it a popular destination for tourists, surfers and volcanologists.
Because of its central location in the Pacific and 19th-century labor migration, Hawaii's culture is influenced by North American and East Asian cultures, in addition to its indigenous Hawaiian culture. Hawaii has over a million permanent residents, along with many visitors and U. S. military personnel. Its capital is Honolulu on the island of Oʻahu. Hawaii is the 8th-smallest and the 11th-least populous, but the 13th-most densely populated of the 50 U. S. states. It is the only state with an Asian plurality; the state's oceanic coastline is about 750 miles long, the fourth longest in the U. S. after the coastlines of Alaska and California. The state of Hawaii derives its name from the name of Hawaiʻi. A common Hawaiian explanation of the name of Hawaiʻi is that it was named for Hawaiʻiloa, a legendary figure from Hawaiian myth, he is said to have discovered the islands. The Hawaiian language word Hawaiʻi is similar to Proto-Polynesian *Sawaiki, with the reconstructed meaning "homeland". Cognates of Hawaiʻi are found in other Polynesian languages, including Māori and Samoan.
According to linguists Pukui and Elbert, "lsewhere in Polynesia, Hawaiʻi or a cognate is the name of the underworld or of the ancestral home, but in Hawaii, the name has no meaning". A somewhat divisive political issue arose in 1978 when the Constitution of the State of Hawaii added Hawaiian as a second official state language; the title of the state constitution is The Constitution of the State of Hawaii. Article XV, Section 1 of the Constitution uses The State of Hawaii. Diacritics were not used because the document, drafted in 1949, predates the use of the ʻokina and the kahakō in modern Hawaiian orthography; the exact spelling of the state's name in the Hawaiian language is Hawaiʻi. In the Hawaii Admission Act that granted Hawaiian statehood, the federal government recognized Hawaii as the official state name. Official government publications and office titles, the Seal of Hawaii use the traditional spelling with no symbols for glottal stops or vowel length. In contrast, the National and State Parks Services, the University of Hawaiʻi and some private enterprises implement these symbols.
No precedent for changes to U. S. state names exists since the adoption of the United States Constitution in 1789. However, the Constitution of Massachusetts formally changed the Province of Massachusetts Bay to the Commonwealth of Massachusetts in 1780, in 1819, the Territory of Arkansaw was created but was admitted to statehood as the State of Arkansas. There are eight main Hawaiian islands; the island of Niʻihau is managed by brothers Bruce and Keith Robinson. Access to uninhabited Kahoʻolawe island is restricted; the Hawaiian archipelago is located 2,000 mi southwest of the contiguous United States. Hawaii is the southernmost U. S. the second westernmost after Alaska. Hawaii, like Alaska, does not border any other U. S. state. It is the only U. S. state, not geographically located in North America, the only state surrounded by water and, an archipelago, the only state in which coffee is commercially cultivable. In addition to the eight main islands, the state has many smaller islets. Kaʻula is a small island near Niʻihau.
The Northwest Hawaiian Islands is a group of nine small, older islands to the northwest of Kauaʻi that extend from Nihoa to Kure Atoll. Across the archipelago are around 130 small rocks and islets, such as Molokini, which are either volcanic, marine sedimentary or erosional in origin. Hawaii's tallest mountain Mauna Kea is 13,796 ft above mean sea level; the Hawaiian islands were formed by volcanic activity initiated at an undersea magma source called the Hawaii hotspot. The process is continuing to build islands; because of the hotspot's location, all active land volcanoes are located on the southern half of Hawaii Island. The newest volcano, Lōʻihi Seamount, is located south of the coast of Hawaii Island; the last volcanic eruption outside Hawaii Island occurred