Fish locomotion
Encyclopedia
The prevailing type of fish locomotion is swimming
in water
. In addition, some fish can "walk", i.e., move over land, burrow
in mud, and glide through the air
.
swim by exerting force against the surrounding water. There are exceptions, but this is normally achieved by the fish contracting muscle
s on either side of its body in order to generate waves of flexion that travel the length of the body from nose to tail, generally getting larger as they go along. The vector force
s exerted on the water by such motion cancel out laterally, but generate a net force backwards which in turn pushes the fish forward through the water.
Most fishes generate thrust using lateral movements of their body & caudal fin. But there are also a huge number of species that move mainly using their median and paired fins. The latter group profits from the gained manoeuvrability that is needed when living in coral reefs for example. But they can't swim as fast as fish using their bodies & caudal fins.
s, for example – there is little increase in the amplitude of the flexion wave as it passes along the body.
use sub-carangiform locomotion.
(new research shows that the thunniform locomotion is an autapomorphy
of the tunas [2]). Here, virtually all the lateral 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.
, for example, have a completely different system, and many small fish use their pectoral fins for swimming as well as for steering and dynamic lift. Fish with electric organs, such as those in Gymnotiformes
, swim by undulating their fins while keeping the body still, presumably so as not to disturb the electric field that they generate.
Bone and muscle tissues of fish are denser than water. To maintain depth some fish increase buoyancy
by means of a gas bladder
or by storing oils or lipids. Fish without these features use dynamic lift instead. It is done using their pectoral fins in a manner similar to the use of wings by aeroplane
s and bird
s. As these fish swim, their pectoral fins are positioned to create lift
which allows the fish to maintain a certain depth.
Shark
s are a notable example of fish that depend on dynamic lift; notice their well-developed pectoral fins.
The two major drawbacks of this method are that these fish must stay moving to stay afloat and that they are incapable of swimming backwards or hovering.
, moray eels, and spiny eel
s, are capable of burrowing
through sand or mud. Ophichthids
are capable of digging backwards using a sharpened tail.
Aquatic locomotion
Swimming is biologically propelled motion through a liquid medium. Swimming has evolved a number of times in a range of organisms ranging from arthropods to fish to molluscs.-Evolution of swimming:...
in water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
. In addition, some fish can "walk", i.e., move over land, burrow
Burrow
A burrow is a hole or tunnel dug into the ground by an animal to create a space suitable for habitation, temporary refuge, or as a byproduct of locomotion. Burrows provide a form of shelter against predation and exposure to the elements, so the burrowing way of life is quite popular among the...
in mud, and glide through the air
Flight
Flight is the process by which an object moves either through an atmosphere or beyond it by generating lift or propulsive thrust, or aerostatically using buoyancy, or by simple ballistic movement....
.
Swimming
FishFish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
swim by exerting force against the surrounding water. There are exceptions, but this is normally achieved by the fish contracting muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
s on either side of its body in order to generate waves of flexion that travel the length of the body from nose to tail, generally getting larger as they go along. The vector force
Force
In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...
s exerted on the water by such motion cancel out laterally, but generate a net force backwards which in turn pushes the fish forward through the water.
Most fishes generate thrust using lateral movements of their body & caudal fin. But there are also a huge number of species that move mainly using their median and paired fins. The latter group profits from the gained manoeuvrability that is needed when living in coral reefs for example. But they can't swim as fast as fish using their bodies & caudal fins.
Body/caudal fin propulsion
There are four groups that differ in the fraction of their body that is displaced laterally [1]:Anguilliform locomotion
In some long, slender fish – eelEel
Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...
s, for example – there is little increase in the amplitude of the flexion wave as it passes along the body.
Sub-carangiform locomotion
Here, there is 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. TroutTrout
Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...
use sub-carangiform locomotion.
Carangiform locomotion
Fish in this group are stiffer and faster-moving than the previous groups. The vast majority of movement is concentrated in the very rear of the body and tail. Carangiform swimmers generally have rapidly oscillating tails.Thunniform locomotion
The final group is reserved for the high-speed long-distance swimmers, like tunaTuna
Tuna is a salt water fish from the family Scombridae, mostly in the genus Thunnus. Tuna are fast swimmers, and some species are capable of speeds of . Unlike most fish, which have white flesh, the muscle tissue of tuna ranges from pink to dark red. The red coloration derives from myoglobin, an...
(new research shows that the thunniform locomotion is an autapomorphy
Autapomorphy
In cladistics, an autapomorphy is a distinctive anatomical feature, known as a derived trait, that is unique to a given terminal group. That is, it is found only in one member of a clade, but not found in any others or outgroup taxa, not even those most closely related to the group...
of the tunas [2]). Here, virtually all the lateral 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.
Median/paired fin propulsion
Not all fish fit comfortably in the above groups. Ocean sunfishOcean sunfish
The ocean sunfish, Mola mola, or common mola, is the heaviest known bony fish in the world. It has an average adult weight of . The species is native to tropical and temperate waters around the globe. It resembles a fish head with a tail, and its main body is flattened laterally...
, for example, have a completely different system, and many small fish use their pectoral fins for swimming as well as for steering and dynamic lift. Fish with electric organs, such as those in Gymnotiformes
Gymnotiformes
The Gymnotiformes are a group of teleost bony fishes commonly known as the Neotropical or South American knifefishes. They have long bodies and swim using undulations of their elongated anal fin...
, swim by undulating their fins while keeping the body still, presumably so as not to disturb the electric field that they generate.
Dynamic lift
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...
by means of a gas bladder
Gas bladder
The swim bladder, gas bladder, fish maw or air bladder is an internal gas-filled organ that contributes to the ability of a fish to control its buoyancy, and thus to stay at the current water depth without having to waste energy in swimming...
or by storing oils or lipids. Fish without these features use dynamic lift instead. It is done using their pectoral fins in a manner similar to the use of wings by aeroplane
Fixed-wing aircraft
A fixed-wing aircraft is an aircraft capable of flight using wings that generate lift due to the vehicle's forward airspeed. Fixed-wing aircraft are distinct from rotary-wing aircraft in which wings rotate about a fixed mast and ornithopters in which lift is generated by flapping wings.A powered...
s and bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s. As these fish swim, their pectoral fins are positioned to create lift
Lift (force)
A fluid flowing past the surface of a body exerts a surface force on it. Lift is the component of this force that is perpendicular to the oncoming flow direction. It contrasts with the drag force, which is the component of the surface force parallel to the flow direction...
which allows the fish to maintain a certain depth.
Shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
s are a notable example of fish that depend on dynamic lift; notice their well-developed pectoral fins.
The two major drawbacks of this method are that these fish must stay moving to stay afloat and that they are incapable of swimming backwards or hovering.
Burrowing
Many fishes, particularly eel-shaped fishes such as true eelsAnguillidae
Anguillidae is a family of fishes that contains the freshwater eels. There are 19 species/subspecies in this family, all in genus Anguilla. They are catadromous, meaning they spend their lives in freshwater rivers, lakes, or estuaries and return to the ocean to spawn...
, moray eels, and spiny eel
Mastacembelidae
The Mastacembelidae are a family of fishes, known as the spiny eels. The Mastacembelids are part of the Order Synbranchiformes, the swamp eels, which are part of the Actinopterygii ....
s, are capable of burrowing
Burrow
A burrow is a hole or tunnel dug into the ground by an animal to create a space suitable for habitation, temporary refuge, or as a byproduct of locomotion. Burrows provide a form of shelter against predation and exposure to the elements, so the burrowing way of life is quite popular among the...
through sand or mud. Ophichthids
Ophichthidae
Ophichthidae is a family of eels, comprising species commonly called worm eels and snake eels. The term "Ophichthidae" comes from Greek ophis and ichthys ....
are capable of digging backwards using a sharpened tail.
See also
- Aquatic locomotionAquatic locomotionSwimming is biologically propelled motion through a liquid medium. Swimming has evolved a number of times in a range of organisms ranging from arthropods to fish to molluscs.-Evolution of swimming:...
- Undulatory locomotionUndulatory locomotionUndulatory locomotion is the type of motion characterized by wave-like movement patterns that act to propel an animal forward. Examples of this type of gait include crawling in snakes, or swimming in the lamprey...
- Tradeoffs for Locomotion in Air and WaterTradeoffs for locomotion in air and waterCertain species of fish and birds are able to locomote in both air and water, two types of fluid media with very different properties. A fluid is a particular phase of matter that deforms under shear stresses and includes any type of liquid or gas...