Tuesday, May 14, 2013

The most important sensory systems are usually the inner ear

The most important sensory systems are usually the inner ear, which responds to sound, and the lateral line, which responds to changes in water pressure. Sony VAIO VGN-SR140E Battery The olfactory system can also be important for males who find females by smell.[48]Bathypelagic fish are black, or sometimes red, with few photophores. When photophores are used, it is usually to entice prey or attract a mate. Because food is so scarce, bathypelagic predators are not selective in their feeding habits, Sony VAIO VGN-SR140E/B Battery but grab whatever come close enough. They accomplish this by having a large mouth with sharp teeth for grabbing large prey and overlapping gill rakers which prevent small prey that have been swallowed from escaping.[45] It is not easy finding a mate in this zone. Some species depend on bioluminescence. Sony VAIO VGN-SR140E/P Battery Others are hermaphrodites, which doubles their chances of producing both eggs and sperm when an encounter occurs.[38] The female anglerfish releases pheromones to attract tiny males. When a male finds her, he bites on to her and never lets go. When a male of the anglerfish speciesHaplophryne mollis bites into the skin of a female, Sony VAIO VGN-SR140E/S Battery he releases an enzyme that digests the skin of his mouth and her body, fusing the pair to the point where the two circulatory systems join up. The male then atrophies into nothing more than a pair of gonads. This extreme sexual dimorphism ensures that, when the female is ready to spawn, she has a mate immediately available.[49] Sony VAIO VGN-SR140N/S Battery Many forms other than fish live in the bathypelagic zone, such as squid, large whales, octopuses, sponges, brachiopods, sea stars, and echinoids, but this zone is difficult for fish to live in. Sampling via deep trawling indicates that lanternfish account for as much as 65% of all deep-sea fish biomass. Sony VAIO VGN-SR165E/B Battery Indeed, lanternfish are among the most widely distributed, populous, and diverse of all vertebrates, playing an important ecologicalrole as prey for larger organisms. With an estimated global biomass of 550 - 660 million metric tons, several times the entire world fisheries catch, Sony VAIO VGN-SR165E/P Battery lanternfish also account for much of the biomass responsible for the deep scattering layer of the world's oceans. In the Southern Ocean, Myctophids provide an alternative food resource to krill for predators such assquid and the King Penguin. Although these fish are plentiful and prolific, currently only a few commercial lanternfishfisheries exist: Sony VAIO VGN-SR165E/S Battery These include limited operations off South Africa, in the sub-Antarctic, and in the Gulf of Oman. A 2006 study by Canadian scientists has found five species of deep-sea fish – blue hake, spiny eel – to be on the verge of extinction due to the shift ofcommercial fishing from continental shelves to the slopes of the continental shelves, down to depths of 1600 meters. Sony VAIO VGN-SR190EBJ Battery The slow reproduction of these fish – they reach sexual maturity at about the same age as human beings – is one of the main reasons that they cannot recover from the excessive fishing. Deep Ocean Water (DOW) is the name for cold, salty water found deep below the surface of Earth's oceans. Sony VAIO VGN-SR190EBQ Battery Ocean water differs in temperature and salinity, with warm, relatively non-salty water found at the surface, and very cold salty water found deeper below the surface layer. Deep ocean water makes up about 90% of the volume of the oceans. Deep ocean water has a very low temperature, typically from 0 °C (32 °F) to 3 °C (37 °F), and a salinity of about 3.5% (35 psu).[1] Sony VAIO VGN-SR190EEJ/C Battery In specialized locations such as the Natural Energy Laboratory of Hawaii NELHA ocean water is pumped to the surface from approximately 3000 feet deep for applications in research, commercial and pre-commercial activities. DOW is typically used to describe ocean water at sub-thermal depths sufficient to provide a measurable difference in water temperature. Sony VAIO VGN-SR190NAB Battery When deep ocean water is brought to the surface, it can be used for a variety of things. Its most useful property is its temperature. At the surface of the Earth, most water and air is well above 3 °C. The difference in temperature is indicative of a difference in energy. Where there is an energy gradient, Sony VAIO VGN-SR190NBB Battery skillful application of science and engineering can harness that energy for productive use by humans. Assuming the source of deep ocean water is environmentally friendly and replenished by natural mechanisms, it forms a more innovative basis for cleaner energy than current fossil-fuel-derived energy. Sony VAIO VGN-SR190NDB Battery The simplest use of cold water is simply for air conditioning: using the cold water itself to cool air saves the energy that would be used by the compressors for traditional refrigeration. Another use could be to replace expensive desalination plants. When cold water passes through a pipe surrounded by humid air, condensation results. Sony VAIO VGN-SR190NEB Battery The condensate is pure water, suitable for humans to drink or for crop irrigation. Finally, via a technology called Ocean thermal energy conversion, the temperature difference can be turned into electricity. Demersal fish live and feed on or near the bottom of the sea or lakes.[1] Sony VAIO VGN-SR190NGB Battery They occupy the sea floors and lake beds, which usually consist of mud, sand, gravel or rocks.[1] In coastal waters they are found on or near thecontinental shelf, and in deep waters they are found on or near the continental slope or along the continental rise. They are not generally found in the deepest waters, Sony VAIO VGN-SR190PAB Battery 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, which means to sink. 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. Sony VAIO VGN-SR190PCB Battery Demersal fish fillets contain little fish oil (one to four percent), whereas pelagic fish can contain up to 30 percent.Demersal fish can be divided into two main types: strictly benthic fish which can rest on the sea floor, and benthopelagicfish which can float in the water column just above the sea floor. Sony VAIO VGN-SR190PFB Battery Benthopelagic fish have neutral buoyancy, so they can float at depth without much effort, while strictly benthic fish are more dense, with negative buoyancy so they can lie on the bottom without any effort.[2] Most demersal fish are benthopelagic.[1] As with other bottom feeders, a mechanism to deal with substrate is often necessary. Sony VAIO VGN-SR19VN Battery With demersal fish the sand is usually pumped out of the mouth through the gill slit. Most demersal fish exhibit a flat ventral region so as to more easily rest their body on the substrate. The exception may be the flatfish, which are laterally depressed but lie on their sides. Sony VAIO VGN-SR19VN Battery Also, many exhibit what is termed an "inferior" mouth, which means that the mouth is pointed downwards; this is beneficial as their food is often going to be below them in the substrate. Those bottom feeders with upward-pointing mouths, such as stargazers, tend to seize swimming prey. Sony VAIO VGN-SR19VRN Battery 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 actively over the bottom in search for food.[3] Benthic fish which can bury themselves include flatfish and stingrays. Sony VAIO VGN-SR19XN Battery Flatfish are an order of ray-finned benthic fishes which lie flat on the ocean floor. Examples are flounder, sole, turbot, plaice, 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. Sony VAIO VGN-SR19XN Battery 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 then changes its habits, and camouflages itself by lying on the bottom of the ocean floor with both eyes facing upwards.[4] The side on which the eye migrates depends on the species, so some species end up with both eyes on their left side, and others on the right. Sony VAIO VGN-SR210J/S Battery Flounder ambush their prey, feeding at soft muddy area of the sea bottom, near bridge piles, docks, artificial and coral reefs. Their diet consists mainly of fish spawn, crustaceans, polychaetes 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. Sony VAIO VGN-SR21M/S Battery It then 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, common and widely distributed, feed on benthopelagic zooplankton. Yet they are strictly benthic fish, since they stay in contact with the bottom. Sony VAIO VGN-SR21RM/H Battery Their fins have long rays they use to "stand" on the bottom while they face the current and grab zooplankton as it passes by.[7] The bodies of benthic fish are adapted for ongoing contact with the sea floor. Swimbladders are usually absent or reduced, and the bodies are usually flattened in one way or another. Sony VAIO VGN-SR21RM/S Battery Benthopelagic fish inhabit the water just above the bottom, feeding on benthos and zooplankton.[13] Most demersal fish are benthopelagic.[1] Deep sea benthopelagic teleosts all have swimbladders. The dominant species, rattails and cusk eels, have considerable biomass. Other species include deep sea cods (morids), deep sea eels, halosaurs and notacanths.[14] Sony VAIO VGN-SR220J/B Battery Benthopelagic sharks, like the deep sea squaloid sharks, achieve neutral buoyancy with the use of large oil-filled livers.[2]Sharks adapt well to fairly high pressures. They can often 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 constantly and maintain a large amount of oil for buoyancy. Sony VAIO VGN-SR220J/H Battery These energy needs cannot be met in the extreme oligotrophic conditions that occur at great depths.[2] Shallow water stingrays are benthic, and can lie on the bottom because of their negative buoyancy. Deep sea stingrays are benthopelagic, and like the squaloids have very large livers which give them neutral buoyancy.[2] Sony VAIO VGN-SR240J/B Battery Benthopelagic fish can be divided into flabby or robust body types. Flabby benthopelagic fishes are like bathypelagic fishes; they have a reduced body mass, and low metabolic rates, expending minimal energy as they lie and wait to ambush prey.[15] An example of a flabby fish is the cusk-eel Acanthonus armatus, Sony VAIO VGN-SR240N/B Battery a predator with a huge head and a body that is 90 percent water. This fish has the largest ears (otoliths) and the smallest brain in relation to its body size of all known vertebrates.[17] Deepwater benthopelagic fish are robust, muscular swimmers that actively cruise the bottom searching for prey. Sony VAIO VGN-SR290JTH Battery They often live around features, such as seamounts, which have strong currents.[17] Commercial examples are the orange roughy and Patagonian toothfish. The edge of the continental shelf marks the boundary where the shelf gives way to, and then gradually drops into abyssaldepths. Sony VAIO VGN-SR290JTJ Battery This edge marks the boundary between coastal, relatively shallow, benthic habitats, and the deep benthic habitats. Coastal demersal fishes live on the bottom of inshore waters, such as bays and estuaries, and further out, on the floor of the continental shelf. Deep water demersal fish live beyond this edge, mostly down the continental slopesand along the continental rises which drop to the abyssal plains. Sony VAIO VGN-SR290JTQ Battery This is the continental margin, constituting about 28% of the total oceanic area.[18] Other deep sea demersal fish can also be found around seamounts and islands. The term bathydemersal fish is sometimes used instead of "deep water demersal fish". Bathydemersal refers to demersal fish which live at depths greater than 200 metres. Sony VAIO VGN-SR290JVB/C Battery The term epibenthic is also used to refer to organism that live on top of the ocean floor, as opposed to those that burrow into the seafloor substrate. However the terms mesodemersalepidemersalmesobenthic and bathybenthic are not used. Coastal demersal fish are found on or near the seabed of coastal waters between the shoreline and the edge of the continental shelf, Sony VAIO VGN-SR290JVH/C Battery where the shelf drops into the deep ocean. Since the continental shelf is generally less than 200 metres deep, this means that coastal waters are generally epipelagic. The term includes demersal reef fish and demersal fish that inhabit estuaries, inlets and bays. Young mangrove jacks, a sought after eating and sport fish, dwell in estuaries around mangrove roots, Sony VAIO VGN-SR290NTB Battery fallen trees, rock walls, and any other snag areas where smaller prey reside for protection. When they mature, they migrate into open waters, sometimes hundreds of kilometres from the coast to spawn. Stargazers are found worldwide in shallow waters. Sony VAIO VGN-SR29VN/S Battery They have eyes on top of their heads and a large upward-facing mouth. They bury themselves in sand, and leap upwards to ambush benthopelagic fish and invertebrates that pass overhead. Some species have a worm-shaped lure growing out of the floor of the mouth, which they wiggle to attract prey. Stargazers arevenomous and can deliver electric shocks. Sony VAIO VGN-SR29XN/S Battery They have been called "the meanest things in creation."Other examples of coastal demersal fish are cod, plaice, monkfish and sole. Deep water demersal fish occupy the benthic regions beyond the continental margins. On the continental slope, demersal fishes are common. Sony VAIO VGN-SR2RVN/S Battery They are more diverse than coastal demersal fish, since there is more habitat diversity. Further out are the abyssal plains. These flat, featureless regions occupy about 40 percent of the ocean floor. They are covered with sediment but largely devoid of benthic life (benthos). Sony VAIO VGN-SR390NAB Battery Deep sea benthic fishes are more likely to associate with canyons or rock outcroppings among the plains, where invertebrate communities are established. Undersea mountains (seamounts) can intercept deep sea currents, and cause productive upwellings which support benthic fish. Undersea mountain ranges can separate underwater regions into different ecosystems. Sony VAIO VGN-SR390NAH Battery Rattails and brotulas are common, and other well established families are eels, eelpouts, hagfishes, greeneyes, batfishes andlumpfishes.[26] The bodies of deep water demersal fishes are muscular with well developed organs. In this way they are closer to mesopelagic fishes than bathypelagic fishes. Sony VAIO VGN-SR41M/P Battery In other ways, they are more variable. Photophores are usually absent, eyes and swimbladdersrange from absent to well developed. They vary in size, and larger species, greater than one metre, are not uncommon. Deep sea demersal fish are usually long and narrow. Many are eels or shaped like eels. Sony VAIO VGN-SR41M/S Battery This may be because long bodies have long lateral lines. Lateral lines detect low-frequency sounds, and some demersal fishes have muscles that drum such sounds to attract mates.[27] Smell is also important, as indicated by the rapidity with which demersal fish find traps baited with bait fish. Sony VAIO VGN-SR49VN/H Battery The main diet of deep sea demersal fish is invertebrates of the deep sea benthos and carrion. Smell, touch and lateral line sensitivities seem to be the main sensory devices for locating these.[3] Like coastal demersal fish, deep sea demersal fish can be divided into benthic fish and benthopelagic fish, Sony VAIO VGN-SR51B/P Battery where the benthic fish are negatively buoyant and benthopelagic fish are neutrally buoyant.[3] The availability of plankton for food diminishes rapidly with depth. At 1000 metres, the biomass of plankton is typically about 1 percent of that at the surface, and at 5000 metres about 0.01 percent.[14] Sony VAIO VGN-SR51B/S Battery Given there is no sunlight, energy enters deep water zones as organic matter. There are three main ways this happens. Firstly, organic matter can move into the zone from the continental landmass, for example, through currents that carry the matter down rivers, then plume along the continental shelf and finally spill down the continental slope. Sony VAIO VGN-SR51MF Battery Other matter enters as particulate matter raining down from the overhead water column in the form of marine snow, or as sinking overhead plant material such as eelgrass, or as "large particles" such as dead fish and whales sinking to the bottom. A third way energy can arrive is through fish, Sony VAIO VGN-SR51MF/P Battery such as vertically migrating mesopelagic fishes that can enter into the demersal zone as they ascend or descend. The demersal fish and invertebrates consume organic matter that does arrive, break it down and recycle it. A consequence of these energy delivery mechanisms is that the abundance of demersal fish and invertebrates gradually decrease as the distance from continental shorelines increases.[28] Sony VAIO VGN-SR51MF/S Battery Although deep water demersal fish species are not generally picky about what they eat, there is still some degree of specialisation. For example, different fish have different mouth sizes, which determines the size of the prey they can handle. Some feed mostly on benthopelagic organisms. Sony VAIO VGN-SR51MF/W Battery Others fed mostly on epifauna(invertebrates on top of the seafloor surface, also called epibenthos), or alternatively on infauna (invertebrates that burrow into the seafloor substrate). Infauna feeders can have considerable sediment in their stomachs. Scavengers, such as snubnosed eels and hagfish, also eat infauna as a secondary food source. Sony VAIO VGN-SR51MR Battery Some feed on carrion. Cameras show that when a dead fish is placed on the bottom, vertebrate and invertebrate scavengers appear very quickly. If the fish is large, some scavengers burrow in and eat it from the inside out. Some fish, such as grenadiers, also appear and start feeding on the scavenging inverebrates andamphipods. Sony VAIO VGN-SR59VG Battery Other specialization is based on depth distribution. Some of the more abundant upper continental slope fish species, such as cutthroat eel andlongfinned hake,[31] mainly feed on on epipelagic fish. But generally, the most abundant deep water demersal fish species feed on invertebrates. Sony VAIO VGN-SR59VG/H Battery At great depths, food scarcity and extreme pressure limits the ability of fish to survive. The deepest point of the ocean is about 11,000 metres. Bathypelagic fishes are not normally found below 3,000 metres.[33] It may be that extreme pressures interfere with essential enzyme functions.[34] Sony VAIO VGN-SR70B/S Battery The deepest-living fish known, the strictly benthic Abyssobrotula galatheae, eel-like and blind, feeds on benthic invertebrates. A living example was trawled from the bottom of the Puerto Rico Trench in 1970 from a depth of 8,370 metres (27,453 ft).Sony VAIO VGN-SR72B/P Battery In 2008, a shoal of 17 hadal snailfish, a species of deep water snailfish, was filmed by a UK-Japan team using remote operated landers at depths of 7.7 km (4.8 mi) in the Japan Trench in the Pacific. The fish were 30 centimetres long (12 in), and were darting about, using vibration sensors on their nose to catch shrimps. Sony VAIO VGN-SR72B/S Battery The team also reported that the appearance of the fish, unlike that of most deep sea fish, was surprisingly "cute", and that they were surprised by how active the fish were at these depths. Black sea bass inhabit US coasts from Maine to NE Florida and the eastern Gulf of Mexico, and are most abundant off the waters of New York. Sony VAIO VGN-SR73JB/S Battery They are found in inshore waters (bays and sounds) and offshore in waters up to a depth of 130 m (425'). They spend most of their time close to the sea floor and are often congregated around bottom formations such as rocks, man-made reefs, wrecks, jetties, piers, and bridge pilings. Sony VAIO VGN-SR74FB/S Battery Black sea bass are sought after recreational and commercial fish, and have been overfished.[43] Grouper are often found around reefs. They have stout bodies and large mouths. They are not built for long-distance or fast swimming. They can be quite large, and lengths over a meter and weights up to 100 kg are not uncommon. Sony VAIO VGN-SR90FS Battery They swallow prey rather than biting pieces off it. They do not have many teeth on the edges of their jaws, but they have heavy crushing tooth plates inside the pharynx. They lie in wait, rather than chasing in open water. They are found in areas of hard or consolidated substrate, and use structural features such as ledges, Sony VAIO VGN-SR90NS Battery rocks, and coral reefs ( as well as artificial reefs like wrecks and sunken barges) as their habitat. Their mouth and gills form a powerful sucking system that sucks their prey in from a distance. They also use their mouth to dig into sand to form their shelters under big rocks, jetting it out through their gills. Sony VAIO VGN-SR90S Battery Their gill muscles are so powerful that it is nearly impossible to pull them out of their cave if they feel attacked and extend those muscles to lock themselves in. There is some research indicating that roving coral groupers (Plectropomus pessuliferus) sometimes cooperate with giant morays in hunting.[44] Sony VAIO VGN-SR90US Battery Deepwater benthopelagic fish are robust, muscular swimmers that actively cruise the bottom searching for prey. They often live around features, such asseamounts, which have strong currents.[17] Commercial examples are the orange roughy and Patagonian toothfish. Sony VAIO VGN-SR91NS Battery Because these fish were once abundant, and because their robust bodies are good to eat, these fish have been commercially harvested. Sony VAIO VGN-SR91PS Battery,Sony VAIO VGN-SR91S Battery,Sony VAIO VGN-SR91US Battery

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