Fish Motion and Underwater Pressure
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Fish swim all the time swim swim swim and even deal with underwater pressure, two feats that humans could NEVER manage. "What is it about fish's shapes and their internal respiration systems that allow them to do so?" I hear you ask. Well, this is a question that scientists and anglers have long contemplated and in recent years, researchers have started to tackle (mind the pun).
In 1984, Michigan zoologist Paul Webb published research papers noting certain "patterns of convergence in [fish's] body shapes". Tuna and sharks both have bodies suited to steam through the waters at high speeds; pike's bodies are thick, making them good at accelerating; and flounders have highly flexible builds that are ideal for high-speed manoeuvres and rapid acceleration but the roundedness of their form prevents them from sustaining quick motion for long... so, they flounder a lot really... Poor Paul Webb did not, however, have a great deal of empirical data. Other research done by E.G. Drucker and G.V. Lauder revealed that "black surfperch (Embiotoca jacksoni) and bluegill sunfish (Lepomis macrochirus) swim at low speeds using their pectoral fins exclusively, and at higher speeds switch to combined pectoral and caudal fin locomotion."
Kara Feilich, a Harvard graduate in comparative bio-mechanics, decided to examine and test the notion that a fish's functioning is directly related to its form and presented some of her results at the annual Society for Integrative and Comparative Biology (San Francisco) in 2013. To carry out her investigations, she attached plastic strips shaped of four different shapes and thickness to robotic fish to imitate fish tails. She also tried using fresh fish tails... Though a tail of medium stiffness and size seemed to enable the swim to fish fastest, the picture is a bit more complex. The mechanics of fish motion in water is an area of research that progresses along with advances in the hugely complex study of hydrodynamics. Feilich, nonetheless, still hopes that "uncovering the secrets of fish motion [will] help engineers build better biomimetic robots underwater". Biomimetics imitate elements of nature for the purpose of solving complex human issues and have in the past helped solve engineering problems such as the harnessing of solar energy. In this area, specialists in biology and in physics (particularly engineering) must work together and draw from each other in order to attempt to answer evolutionary questions.
Part of the trouble with making assumptions regarding the relationship between motion and body form is that there are other factors that influence fish body evolution. For example, lantern-fish, which live beneath the photic zone of the oceans, have evolved to have an esca at the tip of a modified dorsal ray in order to lure prey. In Paul Webb's words, fish "have different histories, niches and trade-offs".
The question of drag whilst fish and sea-mammals swim is an interesting one that could potentially be applied to human swimming too. The speeds at which dolphins can swim, for example, seem impossible when drag, water density and dolphin's volume of muscle are taken into consideration. The quest for discovery began in 1936 with Sir James Gray, whose colleague had spotted a dolphin racing through the water at 23 mph: the average speed of a car driving in a city. Gray calculated how much energy a dolphin would need to be able to do this and the result was that it would need 7 times as much muscle as it has. They must, then have some facility to reduce the impact of drag upon their motion. Biologist Frank Fish reckons that this property could be used for submarines or human swimsuits. It turns out that the truth is possibly simpler than previously thought: it's a dolphin's shape, skin and blubber that allow it to swim so quickly.
For many fish, swimming through turbulent water is actually easier and more efficient than through calm water. Their body structure is such that they can use the water energy to propel themselves forwards, whilst their bodies perform certain contortions from side to side allowing for capitalization on turbulence. This finding was central to a the research of James Liao, who became interested in fish motion fishing with his parents in Brooklyn Park as a child. "In consultation with his adviser, professor of biology George Lauder, and Michael Triantafyllou and David Beal of MIT’s department of ocean engineering, Liao inserted fine wire electrodes into the muscles of rainbow trout to measure their activity and, indirectly, the fishes’ energy expenditure. Fish in choppy water, he determined, are not so much swimming as 'going with the flow.' " Fish's swimming method varies as they travel from calm to turbulent water - from active to passive motion. In calm water, they swim actively by streamlining their bodies and rapidly fluttering their tails; in turbulent water, they allow themselves to flap from side to side. This is fantastic for energy conservation... Trout are a notable example of fish that do this. "Liao's work even has metaphorical implications. His findings debunk the image of heroic salmon fighting their way upstream to spawn. That swim against the current is probably easier than we thought."
Fish, particularly those that swim in the deep, withstand HUGE pressure. It's mind blowing - positively mind blowing! Many deep sea-animals are able to survive this pressure because their bodies are mostly composed of liquid and so not easily compressed. Equally, some fish have gas-filled swim bladders that are easily compressed. To deal with pressure changes, air can be added or removed so that the size of the bladder doesn't increase in shallow water or decrease in deep water. Some fish bodies are also adapted to be buoyant; they have light flesh and bones. This lets them swim up and down without too much expenditure of energy. Some, heavier, species sink if they stop swimming and so spend much of their time of the sea bed.
See more
http://jeb.biologists.org/content/203/16/2379.abstract
http://physicsbuzz.physicscentral.com/2013/01/uncovering-function-of-fish-shapes.html
http://arxiv.org/abs/1006.1927
http://discovermagazine.com/2006/feb/physics-swimming
http://harvardmagazine.com/2004/03/the-way-of-trout.html
http://www.nhm.ac.uk/nature-online/earth/oceans/deep-ocean-life/challenges/ocean-pressure/index.html
In 1984, Michigan zoologist Paul Webb published research papers noting certain "patterns of convergence in [fish's] body shapes". Tuna and sharks both have bodies suited to steam through the waters at high speeds; pike's bodies are thick, making them good at accelerating; and flounders have highly flexible builds that are ideal for high-speed manoeuvres and rapid acceleration but the roundedness of their form prevents them from sustaining quick motion for long... so, they flounder a lot really... Poor Paul Webb did not, however, have a great deal of empirical data. Other research done by E.G. Drucker and G.V. Lauder revealed that "black surfperch (Embiotoca jacksoni) and bluegill sunfish (Lepomis macrochirus) swim at low speeds using their pectoral fins exclusively, and at higher speeds switch to combined pectoral and caudal fin locomotion."
Kara Feilich, a Harvard graduate in comparative bio-mechanics, decided to examine and test the notion that a fish's functioning is directly related to its form and presented some of her results at the annual Society for Integrative and Comparative Biology (San Francisco) in 2013. To carry out her investigations, she attached plastic strips shaped of four different shapes and thickness to robotic fish to imitate fish tails. She also tried using fresh fish tails... Though a tail of medium stiffness and size seemed to enable the swim to fish fastest, the picture is a bit more complex. The mechanics of fish motion in water is an area of research that progresses along with advances in the hugely complex study of hydrodynamics. Feilich, nonetheless, still hopes that "uncovering the secrets of fish motion [will] help engineers build better biomimetic robots underwater". Biomimetics imitate elements of nature for the purpose of solving complex human issues and have in the past helped solve engineering problems such as the harnessing of solar energy. In this area, specialists in biology and in physics (particularly engineering) must work together and draw from each other in order to attempt to answer evolutionary questions.
Part of the trouble with making assumptions regarding the relationship between motion and body form is that there are other factors that influence fish body evolution. For example, lantern-fish, which live beneath the photic zone of the oceans, have evolved to have an esca at the tip of a modified dorsal ray in order to lure prey. In Paul Webb's words, fish "have different histories, niches and trade-offs".
The question of drag whilst fish and sea-mammals swim is an interesting one that could potentially be applied to human swimming too. The speeds at which dolphins can swim, for example, seem impossible when drag, water density and dolphin's volume of muscle are taken into consideration. The quest for discovery began in 1936 with Sir James Gray, whose colleague had spotted a dolphin racing through the water at 23 mph: the average speed of a car driving in a city. Gray calculated how much energy a dolphin would need to be able to do this and the result was that it would need 7 times as much muscle as it has. They must, then have some facility to reduce the impact of drag upon their motion. Biologist Frank Fish reckons that this property could be used for submarines or human swimsuits. It turns out that the truth is possibly simpler than previously thought: it's a dolphin's shape, skin and blubber that allow it to swim so quickly.
For many fish, swimming through turbulent water is actually easier and more efficient than through calm water. Their body structure is such that they can use the water energy to propel themselves forwards, whilst their bodies perform certain contortions from side to side allowing for capitalization on turbulence. This finding was central to a the research of James Liao, who became interested in fish motion fishing with his parents in Brooklyn Park as a child. "In consultation with his adviser, professor of biology George Lauder, and Michael Triantafyllou and David Beal of MIT’s department of ocean engineering, Liao inserted fine wire electrodes into the muscles of rainbow trout to measure their activity and, indirectly, the fishes’ energy expenditure. Fish in choppy water, he determined, are not so much swimming as 'going with the flow.' " Fish's swimming method varies as they travel from calm to turbulent water - from active to passive motion. In calm water, they swim actively by streamlining their bodies and rapidly fluttering their tails; in turbulent water, they allow themselves to flap from side to side. This is fantastic for energy conservation... Trout are a notable example of fish that do this. "Liao's work even has metaphorical implications. His findings debunk the image of heroic salmon fighting their way upstream to spawn. That swim against the current is probably easier than we thought."
Fish, particularly those that swim in the deep, withstand HUGE pressure. It's mind blowing - positively mind blowing! Many deep sea-animals are able to survive this pressure because their bodies are mostly composed of liquid and so not easily compressed. Equally, some fish have gas-filled swim bladders that are easily compressed. To deal with pressure changes, air can be added or removed so that the size of the bladder doesn't increase in shallow water or decrease in deep water. Some fish bodies are also adapted to be buoyant; they have light flesh and bones. This lets them swim up and down without too much expenditure of energy. Some, heavier, species sink if they stop swimming and so spend much of their time of the sea bed.
See more
http://jeb.biologists.org/content/203/16/2379.abstract
http://physicsbuzz.physicscentral.com/2013/01/uncovering-function-of-fish-shapes.html
http://arxiv.org/abs/1006.1927
http://discovermagazine.com/2006/feb/physics-swimming
http://harvardmagazine.com/2004/03/the-way-of-trout.html
http://www.nhm.ac.uk/nature-online/earth/oceans/deep-ocean-life/challenges/ocean-pressure/index.html