Fishes do locomotion in many forms like Jumping, Flying, Climbing, swimming, walking, etc. Fins are known as the primary organ of locomotion. There are five types of fins commonly found in fishes – (1) Dorsal fin (2) Pectoral fin (3) Pelvic fin (4) Anal fin & (5) Caudal fin. Apart from fins muscles fibers and gills play important role in locomotion.
Types of locomotion in fishes
(1) Anguilliform locomotion
(2) Ostraciform locomotion
(3) Carangiform locomotion
(1) Anguilliform locomotion – this is also known as eel-like locomotion because This type of locomotion mostly ell like fishes. This type of locomotion is the result of alternative contraction and relaxation of myomeres. Propulsive force is generated by most of the body.
(2) Ostraciform locomotion – This kind of locomotion is found in trunk-like fishes and this kind of locomotion is also known as wig-wag motion. The alternative contraction and expansion of myomere muscles take place in the locomotion of fish. The propulsive force is generated by only caudal or tail region.
(3) Carangiform locomotion – this type of locomotion is found in Jaw-like fishes. The contraction and expansion of myomere muscle take place on this process and propulsive force is genereted by posterior half of the body.
Locomotion due to contraction and expansion of myomere muscles
Breeder was the first scientist who described the moment due to the contraction and expansion of myomere muscles. Alternative contraction and expansion creates a type of wave which helps the fish to go forward or in general term these alternative contraction and expansion helps the fish in locomotion. In the initial of this process, One side of myomere muscles contract and form a curve in the direction of the contraction and the opposite muscles expanses. In the next step the muscles which were expanded, contacts and contracted muscles expanses. This process is all about alternative contraction and expansion of myomere muscle on each side of body. In the result of contraction and expansion of myomere continuously waves are formed in backward direction and fish moves forward. This type of locomotion is known as Anguilliform locomotion and generally found in eels.
Gray was the scientist who further worked on this theory and he also explained the expansion and contraction of myomere muscles and formation of waves. He explained about this theory in dogfish.
Locomotion due to fins
Fins are known as one of the most important in locomotion. Fishes have different types of fins like – Dorsal fin, Pectoral fin, Pelvic fin, anal fin and caudal fin. These fins help in locomotion of fish. Every fin play different role in locomotion like balancing the body, forward thrust, going deeper or upper in the water. These movements are controlled by different fins.
Haris described the role of fins and two type of motions (1) rolling or yawing and (2) pitching movement. Here yawing movement mean left and right turn during swimming and pitching movement mean diving and rising movement.
The caudal fin gives forward thrust to fish and fish move forward but some time it produces negetive pitching effect cause diving head to caunter balance this paired fins are used. In the use of all fins fish can move and don’t face balancing problem. The role of pelvic fins are less because of backward positioning.
Locomotion due to Gills
Gills are also responsible for locomotion in fishes. Gills are not always used as locomotory organ that’s why people don’t notice it as locomotory organ. It gives initial boost or give forward thrust. We all know that gills are respiratory organ and fishes inheal water from and take oxigen from it by gills and through out through gills, these throwing water gives movement to fish. When fish lives water from gills in speed then fish moves forward this way gills are helpful in fish locomotion.
Acting forces on fishes
(1) Gravity – gravitation force work on all living and non organism on earth. Gravitation force attract the fish toward the earth.
(2) Upliftment – the fins are used to uplift the fish in opposite of gravitational force so fish can swim on water.
(3) Yawing/Rolling – some fishes body are flat or roll, if we put this kind of any object on water which doesn’t use etra force then object will roll on water. Same force also work on fish but fins counterbalance this force.
(4) Pitching – pitching mean diving deep and rising or going up in water. This force is mainly generated by caudal fin and muscle fibers.
(5)Forward thrust – caudal fin gives forward thrust force.
Form of locomotion in fishes
(1) Jumping – Some fishes jump to capture prey and run away from predators. This is common type of locomotion in fishes. They use their caudal fin to jump from water. Eg – Mullet Fish
(2) Flying – fishes don’t fly like birds but some fishes can glide on air for few seconds or minutes. For gliding their fins are specially adapted. Their pectoral fin works like a parachute. Eg – exocoetus and Dachylopterus.
(3) Climbing – some fishes can climb on trees or in surface. They use their opercular spines to climb on trees. Eg – Climbing Perch.
(4) Walking – in this type of locomotion pectoral fin is modified into 3-4 finger like rays which is used to walk as insects. Eg – Cephalocanthus.
(5) Crawling – Some fishes crawl at the surface of bottom sea. Their pectoral fins are modified for this type of locomotion. Eg – Lophius.
(6) Tetrapod like walking – some fishes move slowly like mud puppy or salamander. They look like walking like tetrapod. Eg – Neoceratodus.
(7) Burrowing – fishes burrow on the beach or edge of the river and pond. Eg – eel.
What do fishes use for locomotion
In locomotion of fish myomere muscle and fins play important role. Alternative contraction and expansion helps in movement of fish. Caudal fin gives forward thrust to the fish also other fins play key role in balanced locomotion and turning direction. Water burst from gills is also known as locomotion method in fishes.
How do fish moves up and down in water
This type of movement is called Pitching. Caudal fin is known for forward thrust but it process negative pitching effect mean when fish have to dive deep then they use caudal fin and for upliftment in water or going up in water Pectoral fins are used which caunter balance the negative pitching effect and also used in going up in water.
How do fish change direction
In a straight moving fish direction changing could be going up and down or going left and right. We already discussed about going up and down in above paragraph and going left and right is known vas yawing movement. For this movement dorsal and anal play majority role and also pectoral fin. Like when fish have turn left then they use weak force in left side pectoral fin and uses strong force in right side pectoral fin. Also gills can be used on left and right turn by releasing water burst on the opposite direction of turn. Like if fish is willing to turn right then he/she will hold right operculum tightly and leave water from left operculum in speed.
How do fishes reduce drag
To reduce to drag in water their body shape is streamline mean from and back back structure is sharp and also they have mucus gland to reduce the drag.
How do fishes walk
Some fishes are known as walking fish, they show walking movement. For this their fins are modified specially Pectoral fin. We all know that fins have fin rays. These fin rays of pectoral fins are modified into finger like structure which work like legs and this way fish show walking locomotion. Walking locomotion found in Cephalocanthus.