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Swim bladder

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Title: Swim bladder  
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Swim bladder

The swim bladder of a rudd
Internal positioning of the swim bladder of a bleak
S: anterior, S': posterior portion of the air bladder
œ: œsophagus; l: air passage of the air bladder

The swim bladder, gas bladder, fish maw or air bladder is an internal gas-filled fish to control its buoyancy, and thus to stay at its current water depth without having to waste energy in swimming.[1] Also, the dorsal position of the swim bladder means the center of mass is below the center of volume, allowing it to act as a stabilizing agent. Additionally, the swim bladder functions as a resonating chamber, to produce or receive sound.

The swim bladder is evolutionarily homologous to the lungs. Charles Darwin remarked upon this in On the Origin of Species.[2]

Swim bladders are found in many bony fish, but are not found in cartilaginous fish.[3] In the embryonic stages some species, such as redlip blenny,[4] 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. The cartilaginous fish (e.g. sharks and rays) do not have swim bladders. Some of them can control their depth only by swimming (using dynamic lift); others store fats or oils with density less than that of seawater to produce a neutral or near neutral buoyancy, which does not change with depth.

The gas/tissue interface at the swim bladder produces a strong reflection of sound, which is used in sonar equipment to find fish.

Contents

  • Structure and function 1
  • Evolution 2
  • Deep scattering layer 3
  • Human uses 4
  • Swim bladder disease 5
  • Risk of injury 6
  • Similar structures in other organisms 7
  • Gallery 8
  • References 9
  • Further references 10

Structure and function

Swim bladder from a bony (teleost) fish
How gas is pumped into the swim bladder using counter-current exchange.

The swim bladder normally consists of two gas-filled sacs located in 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 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 [6]

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 the bladder would burst. Physostomes can "burp" out gas, though this complicates the process of re-submergence.

In some fish, mainly freshwater species (e.g. [6]

In red-bellied piranha, the swimbladder 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 swimbladder.[7]

Evolution

The West African lungfish possesses a lung homologous to swim bladders

"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 the swimbladder is homologous, or “ideally similar” in position and structure with the lungs of the

Charles Darwin, 1859[2]

Swim bladders are evolutionarily closely related (i.e., vertebrates and some fish (e.g., lungfish, gar, and bichir) and into the swim bladders of the ray-finned fish.[8] 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.

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.[8] Correspondingly, these fish also have a heterocercal and pectoral fins which provides the necessary lift needed due to the lack of swim bladders. On the other hand, teleost fish with swim bladders have neutral buoyancy and have no need for this lift.[9]


Deep scattering layer

Most mesopelagic fishes are small filter feeders which ascend at night using their swimbladders to feed in the nutrient rich waters of the epipelagic zone. During the day, they return to the dark, cold, oxygen deficient waters of the mesopelagic where they are relatively safe from predators. Lanternfish account for as much as 65 percent of all deep sea fish biomass and are largely responsible for the deep scattering layer of the world's oceans.

Sonar operators, using the newly developed sonar technology during World War II, were puzzled by what appeared to be 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 pass over the moon.[10]

Most mesopelagic fish make daily vertical migrations, moving at night into the epipelagic zone, often following similar migrations of zooplankton, and returning to the depths for safety during the day.[11][12] These vertical migrations often occur over a large vertical distances, and are undertaken with the assistance of a swimbladder. The swimbladder is inflated when the fish wants to move up, and, given the high pressures in the messoplegic zone, this requires significant energy. As 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.[13] Some mesopelagic fishes make daily migrations through the thermocline, where the temperature changes between 10 and 20 °C, thus displaying considerable tolerances for temperature change.

Sampling via deep metric tonnes, several times the entire 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 the millions of lanternfish swim bladders, giving the appearance of a false bottom.[15]

Human uses

In some Asian cultures, the swim bladders of certain large fishes are considered a food delicacy. In China they are known as fish maw, 花膠/鱼鳔,[16] and are served in soups or stews. 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 the clarification of beer. In earlier times they were used to make condoms.[17]

Swim bladder disease

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.[18]

Risk of injury

Fish with a swim bladder are at greater risk of injury after exposure to loud impulsive sounds than those without.[19]

Similar structures in other organisms

  • Bond, Carl E. (1996) Biology of Fishes, 2nd ed., Saunders, pp. 283–290.
  • Pelster, Bernd (1997) "Buoyancy at depth" In: WS Hoar, DJ Randall and AP Farrell (Eds) Deep-Sea Fishes, pages 195–237, Academic Press. ISBN 9780080585406.

Further references

  1. ^ "Fish". Microsoft Encarta Encyclopedia Deluxe 1999. Microsoft. 1999. 
  2. ^ a b Darwin, Charles (1859) Origin of Species Page 190, reprinted 1872 by D. Appleton.
  3. ^ http://www.ucmp.berkeley.edu/vertebrates/actinopterygii/actinomm.html
  4. ^ Nursall, J. R. (1989). "Buoyancy is provided by lipids of larval redlip blennies, Ophioblennius atlanticus". Copeia 3: 614–621.  
  5. ^ Pelster B (December 2001). "The generation of hyperbaric oxygen tensions in fish". News Physiol. Sci. 16 (6): 287–91.  
  6. ^ a b "Secretion Of Nitrogen Into The Swimbladder Of Fish. Ii. Molecular Mechanism. Secretion Of Noble Gases". Biolbull.org. 1981-12-01. Retrieved 2013-06-24. 
  7. ^ Onuki, A; Ohmori Y.; Somiya H. (January 2006). "Spinal Nerve Innervation to the Sonic Muscle and Sonic Motor Nucleus in Red Piranha, Pygocentrus nattereri (Characiformes, Ostariophysi)". Brain, Behavior, and Evolution 67: 11–122.  
  8. ^ a b Farmer, Colleen (1997). "Did lungs and the intracardiac shunt evolve to oxygenate the heart in vertebrates" (PDF). Paleobiology. 
  9. ^ Kardong, KV (1998) Vertebrates: Comparative Anatomy, Function, Evolution2nd edition, illustrated, revised. Published by WCB/McGraw-Hill, p. 12 ISBN 0-697-28654-1
  10. ^ Ryan P "Deep-sea creatures: The mesopelagic zone" Te Ara - the Encyclopedia of New Zealand. Updated 21 September 2007.
  11. ^ Moyle and Cech, 2004, p. 585
  12. ^ Bone & Moore 2008, p. 38.
  13. ^ Douglas EL, Friedl WA and Pickwell GV (1976) "Fishes in oxygen-minimum zones: blood oxygenation characteristics" Science, 191 (4230) 957–959.
  14. ^ Hulley, P. Alexander (1998). Paxton, J.R. & Eschmeyer, W.N., ed. Encyclopedia of Fishes. San Diego: Academic Press. pp. 127–128.  
  15. ^ R. Cornejo, R. Koppelmann & T. Sutton. "Deep-sea fish diversity and ecology in the benthic boundary layer". 
  16. ^ Teresa M. (2009) A Tradition of Soup: Flavors from China's Pearl River Delta Page 70, North Atlantic Books. ISBN 9781556437656.
  17. ^ Animal Gut Condoms Retrieved 6 January 2014.
  18. ^ Johnson, Erik L. and Richard E. Hess (2006) Fancy Goldfish: A Complete Guide to Care and Collecting, Weatherhill, Shambhala Publications, Inc. ISBN 0-8348-0448-4
  19. ^ Halvorsen, M. B., Casper, B. M., Matthews, F., Carlson, T. J., & Popper, A. N. (2012). Effects of exposure to pile-driving sounds on the lake sturgeon, Nile tilapia and hogchoker. Proceedings of the Royal Society of London B: Biological Sciences, 279(1748), 4705-4714.
  20. ^ Clark, F. E.; C. E. Lane (1961). "Composition of float gases of Physalia physalis". Fed. Proc. 107: 673–674.  

References


Gallery

[20]

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