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39-526: Barbourisiidae Cetomimidae Rondeletiidae The Cetomimiformes or whalefishes are an order of small, deep-sea ray-finned fish . Some authorities include the whalefishes as part of the order Stephanoberyciformes , within the superfamily Cetomimoidea . Their sister order, the Beryciformes , includes the flashlight fish and squirrelfish . Within this group are five families and approximately 18 genera and 32 species (but see below). Thought to have

78-584: A circumglobal distribution throughout the tropical and temperate latitudes , whalefishes have been recorded at depths in excess of 3,500 metres. Named after their whale-shaped body (from the Greek ketos meaning "whale" or "sea monster", mimos meaning "imitative" and the Latin forma meaning "form"), the Cetomimiformes have extremely large mouths and highly distensible stomachs. Their eyes are very small or vestigial;

117-468: A false sea floor 300–500 metres deep at day, and less deep at night. This turned out to be due to millions of marine organisms, most particularly small mesopelagic fish, with swimbladders that reflected the sonar. These organisms migrate up into shallower water at dusk to feed on plankton. The layer is deeper when the moon is out, and can become shallower when clouds obscure the moon. Most mesopelagic fish make daily vertical migrations , moving at night into

156-420: A gas bladder. Physoclisti can not expel air quickly enough from the gas bladder, the organ most susceptible to sonic damage, thus making it difficult for them to escape major injury. Physostomes, on the other hand, can release air from their gas bladder expeditiously enough to protect it; nevertheless, they can not relieve pressure in their other vital organs, and are therefore also vulnerable to injury. Some of

195-414: A generally whale -shaped body, small pectoral and pelvic fins, and dorsal and anal fins set far back. Body and fins are covered with tiny spicules , resulting in a velvety feel that inspires the name. Colour is an overall vivid geranium red or dark orange. The mouth is large, extending well behind the eyes, has a white interior, and the lower jaw projects beyond the upper jaw. The largest recorded specimen

234-414: A large range of depths. Due to the dorsal position it gives the fish lateral stability. In physostomous swim bladders, a connection is retained between the swim bladder and the gut , the pneumatic duct, allowing the fish to fill up the swim bladder by "gulping" air. Excess gas can be removed in a similar manner. In more derived varieties of fish (the physoclisti ), the connection to the digestive tract

273-436: A length of just 40 centimetres; most species are half this size. Sexual dimorphism is (apparently) exceptionally strong: males may only grow to 3.5 centimetres while females may be ten times as large. This is not uncommon among deep-sea fishes, with the males serving little use other than as suppliers of sperm: an even more extreme case are the parasitic males in deep-sea anglerfish . The gibberfishes ( Gibberichthyidae ) on

312-511: Is evolutionarily homologous to the lungs of tetrapods and lungfish , and some ray-finned fish such as bowfins have also evolved similar respiratory functions in their swim bladders. Charles Darwin remarked upon this in On the Origin of Species , and reasoned that the lung in air-breathing vertebrates had derived from a more primitive swim bladder as a specialized form of enteral respiration . In

351-430: Is lost. In early life stages, these fish must rise to the surface to fill up their swim bladders; in later stages, the pneumatic duct disappears, and the gas gland has to introduce gas (usually oxygen ) to the bladder to increase its volume and thus increase buoyancy . This process begins with the acidification of the blood in the rete mirabile when the gas gland excretes lactic acid and produces carbon dioxide ,

390-485: The Actinopteri (ray-finned fish minus the bichirs ) the lungs evolved into a swim bladder (secondary absent in some lineages), which unlike lungs that bud ventrally, buds dorsally from the anterior foregut. Coelacanths have a "fatty organ" that have sometimes been referred to as a swim bladder, but is structurally different and have a separate evolutionary history. In 1997, Farmer proposed that lungs evolved to supply

429-455: The dorsal portion of the fish, although in a few primitive species, there is only a single sac. It has flexible walls that contract or expand according to the ambient pressure . The walls of the bladder contain very few blood vessels and are lined with guanine crystals, which make them impermeable to gases. By adjusting the gas pressurising organ using the gas gland or oval window, the fish can obtain neutral buoyancy and ascend and descend to

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468-537: The lateral line (composed of huge, hollow tubes) is consequently very well developed to compensate for life in the pitch black depths. The dorsal and anal fins are set far back; all fins lack spines. The swim bladder is also absent, except in the larvae and juveniles which occur in the surface waters. Whalefish coloration is typically red to orange, sometimes with a black body. Some species possess light-producing organs called photophores ; these are widespread among deep-sea fishes. The largest known species reach

507-560: The macula of saccule in order for the inner ear to receive a sensation from the sound pressure. In red-bellied piranha , the swim bladder may play an important role in sound production as a resonator. The sounds created by piranhas are generated through rapid contractions of the sonic muscles and is associated with the swim bladder. Teleosts are thought to lack a sense of absolute hydrostatic pressure , which could be used to determine absolute depth. However, it has been suggested that teleosts may be able to determine their depth by sensing

546-458: The saccule and the lagena . They are suited for detecting sound and vibrations due to its low density in comparison to the density of the fish's body tissues. This increases the ability of sound detection. The swim bladder can radiate the pressure of sound which help increase its sensitivity and expand its hearing. In some deep sea fishes like the Antimora , the swim bladder maybe also connected to

585-478: The arteries supplying the gas gland via a countercurrent multiplication loop . Thus a very high gas pressure of oxygen can be obtained, which can even account for the presence of gas in the swim bladders of deep sea fish like the eel , requiring a pressure of hundreds of bars . Elsewhere, at a similar structure known as the 'oval window', the bladder is in contact with blood and the oxygen can diffuse back out again. Together with oxygen, other gases are salted out in

624-449: The bladder would burst. Physostomes can "burp" out gas, though this complicates the process of re-submergence. The swim bladder in some species, mainly fresh water fishes ( common carp , catfish , bowfin ) is interconnected with the inner ear of the fish. They are connected by four bones called the Weberian ossicles from the Weberian apparatus . These bones can carry the vibrations to

663-443: The clarification of beer . In earlier times, they were used to make condoms . Swim bladder disease is a common ailment in aquarium fish . A fish with swim bladder disorder can float nose down tail up, or can float to the top or sink to the bottom of the aquarium. Many anthropogenic activities, such as pile driving or even seismic waves , can create high-intensity sound waves that cause internal injury to fish that possess

702-516: The commonly seen injuries include ruptured gas bladder and renal Haemorrhage . These mostly affect the overall health of the fish but not their mortality rate. Investigators employed the High-Intensity-Controlled Impedance-Fluid-Filled (HICI-FT), a stainless-steel wave tube with an electromagnetic shaker. It simulates high-energy sound waves in aquatic far-field, plane-wave acoustic conditions. Siphonophores have

741-452: The embryonic stages, some species, such as redlip blenny , have lost the swim bladder again, mostly bottom dwellers like the weather fish . Other fish — like the opah and the pomfret — use their pectoral fins to swim and balance the weight of the head to keep a horizontal position. The normally bottom-dwelling sea robin can use their pectoral fins to produce lift while swimming like cartilaginous fish do. The gas/tissue interface at

780-407: The epipelagic zone, often following similar migrations of zooplankton, and returning to the depths for safety during the day. These vertical migrations often occur over large vertical distances, and are undertaken with the assistance of a swim bladder. The swim bladder is inflated when the fish wants to move up, and, given the high pressures in the mesoplegic zone, this requires significant energy. As

819-508: The fish ascends, the pressure in the swimbladder must adjust to prevent it from bursting. When the fish wants to return to the depths, the swimbladder is deflated. Some mesopelagic fishes make daily migrations through the thermocline , where the temperature changes between 10 and 20 °C, thus displaying considerable tolerance for temperature change. Sampling via deep trawling indicates that lanternfish account for as much as 65% of all deep sea fish biomass . Indeed, lanternfish are among

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858-439: The heart with oxygen. In fish, blood circulates from the gills to the skeletal muscle, and only then to the heart. During intense exercise, the oxygen in the blood gets used by the skeletal muscle before the blood reaches the heart. Primitive lungs gave an advantage by supplying the heart with oxygenated blood via the cardiac shunt. This theory is robustly supported by the fossil record, the ecology of extant air-breathing fishes, and

897-404: The latter of which acidifies the blood via the bicarbonate buffer system . The resulting acidity causes the hemoglobin of the blood to lose its oxygen ( Root effect ) which then diffuses partly into the swim bladder. Before returning to the body, the blood re-enters the rete mirabile , and as a result, virtually all the excess carbon dioxide and oxygen produced in the gas gland diffuses back to

936-571: The millions of lanternfish swim bladders, giving the appearance of a false bottom. In the East Asian culinary sphere, the swim bladders of certain large fishes are considered a food delicacy. In Chinese cuisine, they are known as fish maw , 花膠/鱼鳔, and are served in soups or stews. The vanity price of a vanishing kind of maw is behind the imminent extinction of the vaquita , the world's smallest porpoise species. Found only in Mexico's Gulf of California ,

975-399: The most widely distributed, populous, and diverse of all vertebrates , playing an important ecological role as prey for larger organisms. The estimated global biomass of lanternfish is 550–660 million tonnes , several times the annual world fisheries catch. Lanternfish also account for much of the biomass responsible for the deep scattering layer of the world's oceans. Sonar reflects off

1014-407: The necessary lift needed due to the lack of swim bladders. Teleost fish with swim bladders have neutral buoyancy, and have no need for this lift. The swim bladder of a fish can strongly reflect sound of an appropriate frequency. Strong reflection happens if the frequency is tuned to the volume resonance of the swim bladder. This can be calculated by knowing a number of properties of the fish, notably

1053-407: The once numerous vaquita are now critically endangered. Vaquita die in gillnets set to catch totoaba (the world's largest drum fish ). Totoaba are being hunted to extinction for its maw, which can sell for as much $ 10,000 per kilogram. Swim bladders are also used in the food industry as a source of collagen . They can be made into a strong, water-resistant glue, or used to make isinglass for

1092-526: The other hand, usually placed in the Stephanoberyciformes sensu stricto , appear to be close relatives of the Rondeletiidae and Barbourisiidae , as has been occasionally proposed. Barbourisiidae Barbourisidae A.E. Parr, 1945 ( lapsus ) The velvet whalefish ( Barbourisia rufa ) is a deep-sea whalefish , the sole known member of its family Barbourisiidae . It is found throughout

1131-431: The physiology of extant fishes. In embryonal development, both lung and swim bladder originate as an outpocketing from the gut; in the case of swim bladders, this connection to the gut continues to exist as the pneumatic duct in the more "primitive" ray-finned fish, and is lost in some of the more derived teleost orders. There are no animals which have both lungs and a swim bladder. As an adaptation to migrations between

1170-421: The rate of change of swim-bladder volume. The illustration of the swim bladder in fishes ... shows us clearly the highly important fact that an organ originally constructed for one purpose, namely, flotation, may be converted into one for a widely different purpose, namely, respiration. The swim bladder has, also, been worked in as an accessory to the auditory organs of certain fishes. All physiologists admit that

1209-479: The surface and deeper waters, some fish have evolved a swim bladder where the gas is replaced with low-density wax esters as a way to cope with Boyle's law . The cartilaginous fish (e.g., sharks and rays) split from the other fishes about 420 million years ago, and lack both lungs and swim bladders, suggesting that these structures evolved after that split. Correspondingly, these fish also have both heterocercal and stiff, wing-like pectoral fins which provide

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1248-415: The surface. As opposed to adults, they still have a small swim bladder . Young whalefish make nightly vertical migrations into the lower mesopelagic zone to feed on copepods . When males make the transition to adults, they develop a massive liver, and then their jaws fuse shut. They no longer eat, but continue to metabolise the energy stored in their liver. Swim bladder The swim bladder

1287-491: The swim bladder produces a strong reflection of sound, which is used by sonar equipment to find fish . Cartilaginous fish, such as sharks and rays , do not have swim bladders. Some of them can control their depth only by swimming (using dynamic lift ); others store up lipids with density less than that of seawater to produce a neutral or near-neutral buoyancy, which cannot be readily changed with depth. The swim bladder normally consists of two gas-filled sacs located in

1326-525: The swim bladder which accounts for the high pressures of other gases as well. The combination of gases in the bladder varies. In shallow water fish, the ratios closely approximate that of the atmosphere , while deep sea fish tend to have higher percentages of oxygen. For instance, the eel Synaphobranchus has been observed to have 75.1% oxygen, 20.5% nitrogen , 3.1% carbon dioxide , and 0.4% argon in its swim bladder. Physoclist swim bladders have one important disadvantage: they prohibit fast rising, as

1365-439: The swimbladder is homologous, or “ideally similar” in position and structure with the lungs of the higher vertebrate animals: hence there is no reason to doubt that the swim bladder has actually been converted into lungs, or an organ used exclusively for respiration. According to this view it may be inferred that all vertebrate animals with true lungs are descended by ordinary generation from an ancient and unknown prototype, which

1404-622: The tropical and temperate parts of the world's oceans, mainly in the Pacific near Japan and New Zealand , at depths of 300–2,000 m. This species seems very closely related to some flabby whalefish and it was initially believed to belong to that family by some. They have been found from 65°N–40°S in the Atlantic, 50°N–50°S in the Pacific, and 5–20°S in the Indian Ocean. Like other whalefish, it has

1443-452: The volume of the swim bladder, although the well-accepted method for doing so requires correction factors for gas-bearing zooplankton where the radius of the swim bladder is less than about 5 cm. This is important, since sonar scattering is used to estimate the biomass of commercially- and environmentally-important fish species. Sonar operators, using the newly developed sonar technology during World War II, were puzzled by what appeared to be

1482-408: Was 34.5 cm; another fairly large specimen weighed 456  g . Little is known of their habits, but they are believed to feed on crustaceans . The larvae metamorphose into the adult form at about 7 mm standard length . Larvae and immatures inhabit the upper water layers, down to some dozen metres; larvae before notochord flexion/metamorphosis in particular can sometimes be found right at

1521-460: Was furnished with a floating apparatus or swim bladder. Swim bladders are evolutionarily closely related (i.e., homologous ) to lungs . The first lungs originated in the last common ancestor of the Actinopterygii (ray-finned fish) and Sarcopterygii (lobe-finned fish and the tetrapods ) as expansions of the upper digestive tract which allowed them to gulp air under oxygen-poor conditions. In

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