FISH LOCOMOTION is the variety of types of animal locomotion used by fish , principally by swimming . This however is achieved in different groups of fish by a variety of mechanisms of propulsion in water , most often by wavelike movements of the fish's body and tail, and in various specialised fish by movements of the fins . The major forms of locomotion in fish are anguilliform, in which a wave passes evenly along a long slender body; sub-carangiform, in which the wave increases quickly in amplitude towards the tail; carangiform, in which the wave is concentrated near the tail, which oscillates rapidly; thunniform, rapid swimming with a large powerful crescent-shaped tail; and ostraciiform, with almost no oscillation except of the tail fin. More specialised fish include movement by pectoral fins with a mainly stiff body, as in the sunfish; and movement by propagating a wave along the long fins with a motionless body in fish with electric organs such as the knifefish .
In addition, some fish can variously "walk", i.e., move over land, burrow in mud, and glide through the air .
* 1 Swimming
* 1.1 Body/caudal fin propulsion
* 1.1.1 Anguilliform * 1.1.2 Sub-carangiform * 1.1.3 Carangiform * 1.1.4 Thunniform * 1.1.5 Ostraciiform
* 1.2 Median/paired fin propulsion
* 1.2.1 Rajiform * 1.2.2 Diodontiform * 1.2.3 Amiiform * 1.2.4 Gymnotiform * 1.2.5 Balistiform
* 1.2.6 Oscillatory
* 188.8.131.52 Tetraodontiform * 184.108.40.206 Labriform
* 1.3 Dynamic lift
* 1.4 Hydrodynamics
* 1.4.1 Body-caudal fin
* 1.5 Adaptation
* 3 Walking * 4 Burrowing * 5 See also * 6 References * 7 Further reading * 8 External links
BODY/CAUDAL FIN PROPULSION
There are five groups that differ in the fraction of their body that is displaced laterally:
Eels propagate a more or less constant-sized flexion wave along their slender bodies.
In the anguilliform group, containing some long, slender fish such as eels , there is little increase in the amplitude of the flexion wave as it passes along the body.
The sub-carangiform group has a more marked increase in wave
amplitude along the body with the vast majority of the work being done
by the rear half of the fish. In general, the fish body is stiffer,
making for higher speed but reduced maneuverability.
The carangiform group, named for the
Tunas such as the bluefin swim fast with their large crescent-shaped tails.
The thunniform group contains high-speed long-distance swimmers, and is a unique trait (an autapomorphy) of the tunas . Here, virtually all the sideways movement is in the tail and the region connecting the main body to the tail (the peduncle). The tail itself tends to be large and crescent shaped.
The ostraciiform group have no appreciable body wave when they employ caudal locomotion. Only the tail fin itself oscillates (often very rapidly) to create thrust . This group includes Ostraciidae .
MEDIAN/PAIRED FIN PROPULSION
Boxfish use median-paired fin swimming, as they are not well streamlined, and use primarily their pectoral fins to produce thrust.
Not all fish fit comfortably in the above groups.
Many fish swim using combined behavior of their two pectoral fins or both their anal and dorsal fins. Different types of Median paired fin propulsion can be achieved by preferentially using one fin pair over the other, and include rajiform, diodontiform, amiiform, gymnotiform and balistiform modes.
Rajiform locomotion is characteristic of rays , skates , and mantas when thrust is produced by vertical undulations along large, well developed pectoral fins.
Porcupine fish (here,
Diodontiform locomotion propels the fish propagating undulations along large pectoral fins, as seen in the porcupinefish (Diodontidae ).
Amiiform locomotion consists of undulations of a long dorsal fin while the body axis is held straight and stable, as seen in the bowfin .
Gymnotiform locomotion consists of undulations of a long anal fin, essentially upside down amiiform, seen in the knifefish (Gymnotiformes ).
In balistiform locomotion, both anal and dorsal fins undulate. It is characteristic of the family Balistidae(triggerfishes). It may also be seen in the Zeidae .
In tetraodontiform locomotion, the dorsal and anal fins are flapped as a unit, either in phase or exactly opposing one another, as seen in the Tetraodontiformes (boxfishes and pufferfishes ). The ocean sunfish displays an extreme example of this mode.
In labriform locomotion, seen in the wrasses ( Labriformes ), oscillatory movements of pectoral fins are either drag based or lift based. Propulsion is generated either as a reaction to drag produced by dragging the fins through the water in a rowing motion, or via lift mechanisms.
Sharks are denser than water, and must swim continually, using dynamic lift from their pectoral fins.
Bone and muscle tissues of fish are denser than water. To maintain
depth fish such as sharks , but also some bony fish, increase buoyancy
by means of a gas bladder or by storing oils or lipids .
Similarly to the aerodynamics of flight, powered swimming requires
animals to overcome drag by producing thrust. Unlike flying, however,
swimming animals often do not need to supply much vertical force
because the effect of buoyancy can counter the downward pull of
gravity, allowing these animals to float without much effort. While
there is great diversity in fish locomotion, swimming behavior can be
classified into two distinct "modes" based on the body structures
involved in thrust production, Median-Paired
Play media Sardines use body-caudal fin propulsion to swim, holding their pectoral, dorsal, and anal fins flat against the body, creating a more streamlined body to reduce drag.
Most fish swim by generating undulatory waves that propagate down the
body through the caudal fin . This form of undulatory locomotion is
Similar to adaptation in avian flight, swimming behaviors in fish can be thought of as a balance of stability and maneuverability. Because BCF swimming relies on more caudal body structures that can direct powerful thrust only rearwards, this form of locomotion is particularly effective for accelerating quickly and cruising continuously. BCF swimming is, therefore, inherently stable and is often seen in fish with large migration patterns that must maximize efficiency over long periods. Propulsive forces in MPF swimming, on the other hand, are generated by multiple fins located on either side of the body that can be coordinated to execute elaborate turns. As a result, MPF swimming is well adapted for high maneuverability and is often seen in smaller fish that require elaborate escape patterns.
The habitats occupied by fishes are often related to their swimming capabilities. On coral reefs, the faster-swimming fish species typically live in wave-swept habitats subject to fast water flow speeds, while the slower fishes live in sheltered habitats with low levels of water movement.
In addition to adapting locomotor behavior, controlling buoyancy
effects is critical for aquatic survival since aquatic ecosystems vary
greatly by depth.
See also: flying fish and flying and gliding animals
The transition of predominantly swimming locomotion directly to flight has evolved in a single family of marine fish, the Exocoetidae . Flying fish are not true fliers in the sense that they do not execute powered flight. Instead, these species glide directly over the surface of the ocean water without ever flapping their "wings." Flying fish have evolved abnormally large pectoral fins that act as airfoils and provide lift when the fish launches itself out of the water. Additional forward thrust and steering forces are created by dipping the hypocaudal (i.e. bottom) lobe of their caudal fin into the water and vibrating it very quickly, in contrast to diving birds in which these forces are produced by the same locomotor module used for propulsion. Of the 64 extant species of flying fish, only two distinct body plans exist, each of which optimizes two different behaviors. Flying fish gain sufficient lift to glide above the water thanks to their enlarged pectoral fins.
While most fish have caudal fins with evenly sized lobes (i.e. homocaudal), flying fish have an enlarged ventral lobe (i.e. hypocaudal) which facilitates dipping only a portion of the tail back onto the water for additional thrust production and steering.
Because flying fish are primarily aquatic animals, their body density must be close to that of water for buoyancy stability. This primary requirement for swimming, however, means that flying fish are heavier (have a larger mass) than other habitual fliers, resulting in higher wing loading and lift to drag ratios for flying fish compared to a comparably sized bird. Differences in wing area, wing span, wing loading, and aspect ratio have been used to classify flying fish into two distinct classifications based on these different aerodynamic designs.
BIPLANE BODY PLAN
In the biplane or Cypselurus body plan, both the pectoral and pelvic fins are enlarged to provide lift during flight. These fish also tend to have "flatter" bodies which increase the total lift producing area thus allowing them to "hang" in the air better than more streamlined shapes. As a result of this high lift production, these fish are excellent gliders and are well adapted for maximizing flight distance and duration.
Comparatively, Cypselurus flying fish have lower wing loading and smaller aspect ratios (i.e. broader wings) than their Exocoetus monoplane counterparts, which contributes to their ability to fly for longer distances than fish with this alternative body plan. Flying fish with the biplane design take advantage of their high lift production abilities when launching from the water by utilizing a "taxiing glide" in which the hypocaudal lobe remains in the water to generate thrust even after the trunk clears the water's surface and the wings are opened with a small angle of attack for lift generation. In the monoplane body plan of Exocoetus , only the pectoral fins are abnormally large, while the pelvic fins are small.
MONOPLANE BODY PLAN
In the Exocoetus or monoplane body plan, only the pectoral fins are
enlarged to provide lift.
Main article: Walking fish Play media Alticus arnoldorum hopping Play media Alticus arnoldorum climbing up a vertical piece of Plexiglas
A "walking fish" is a fish that is able to travel over land for extended periods of time. Some other cases of nonstandard fish locomotion include fish "walking" along the sea floor , such as the handfish or frogfish .
Most commonly, walking fish are amphibious fish . Able to spend
longer times out of water, these fish may use a number of means of
locomotion, including springing, snake-like lateral undulation, and
tripod-like walking. The mudskippers are probably the best
land-adapted of contemporary fish and are able to spend days moving
about out of water and can even climb mangroves , although to only
modest heights. The
There are a number of fish that are less adept at actual walking,
such as the walking catfish . Despite being known for "walking on
land", this fish usually wriggles and may use its pectoral fins to aid
in its movement. Walking Catfish have a respiratory system that allows
them to live out of water for several days. Some are invasive species
. A notorious case in the
There are some species of fish that can "walk" along the sea floor
but not on land; one such animal is the flying gurnard (it does not
actually fly, and should not be confused with flying fish ). The
batfishes of the
Many fishes, particularly eel-shaped fishes such as true eels , moray eels , and spiny eels , are capable of burrowing through sand or mud. Ophichthids , the snake eels, are capable of burrowing either forwards or backwards.
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* ^ A B C D E F G H I J K L M N Sfakiotakis, M.; Lane, D. M.;
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* Alexander, R. McNeill (2003) Principles of Animal Locomotion.
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* Eloy, Christophe (2013) "On the best design for undulatory
swimming" Journal of Fluid Mechanics, 717: 48–89. doi
* Lauder GV , Nauen JC and Drucker EG (2002) "Experimental
Hydrodynamics and Evolution: Function of Median Fins in Ray-finned
Fishes" Integr. Comp. Biol. 42 (5): 1009–1017. doi
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