Locomotion:

            Locomotion is a basic skill for animals whether they are invertebrates or vertebrates. The phenomenon helps to go through various environmental conditions and help the animals to move away from their predators. The movement maintains equilibrium condition against gravity.


Vertebrates:

          An animal with a spinal cord, that is surrounded by cartilage or bone is called a vertebrate animal. The word comes from vertebrae, which means the bones that make up the spine of the animal. Vertebrates animals include birds, fish, amphibians, reptiles, birds, and mammals.

Vertebrate Groups:

 There are five groups of  Vertebrate animals. These major groups include;

1.     1.  Fishes

2.     2. Amphibians

3.     3.  Reptiles

4.     4. Birds, and

5.     5.  Mammals. 

The mode of locomotion varies from group to group. The detailed note on each group is given below;

1.    Locomotion in Fishes:

·         Many fish swim through water by creating undulations with their bodies or oscillating their fins. The undulations create components of forwarding thrust complemented by a rearward force, side forces which are wasted portions of energy, and a normal force that is between the forward thrust and side force.

·         Different fishes swim by undulating different parts of their bodies. Gait changes have even been observed in juvenile reef fish of various sizes. Depending on their needs, fish can rapidly alternate between synchronized fin beats and alternating fin beats.

1.1.                    Body-caudal Fin propulsion (BCF):

●        Subcarangiform, Carangiform, and Thunniform swimmers: These swimmers undulate the posterior half of their body and are much faster than anguilliform swimmers. At any point, while they are swimming, a wavelength <1 can be seen in the undulation pattern of the body.

●        Anguilliform swimmers:  Anguilliform swimmers are slow swimmers. They undulate the majority of their body and use their head as the fulcrum for the load they are moving. At any point during their undulation, their body has an amplitude between 0.5-1.0 wavelengths.

 

●        Ostraciiform swimmers: Ostraciiform swimmers oscillate their caudal region, making them relatively slow swimmers. Boxfish, torpedo rays and momyrs employ Ostraciiform locomotion.

1.2.                    Median paired fin propulsion (MPF):

●        Rajiform, Amiiform, Gymnotiform: This mode of locomotion is accomplished by the undulation of the pectoral and median fins. During their undulation pattern, a wavelength >1 can be seen in the fins. They are typically slow to moderate swimmers. Their examples include rays, bowfin, and knife fishes.

●        Tetraodoniform, Balistiform, Diodontiform: These swimmers oscillate their median fins. They are typically slow swimmers, and some notable examples include the oceanic sunfish, pufferfish, and triggers.

 

1.3.                    Buoyancy: Water’s buoyant properties also contribute to the efficiency of a fish’s movement through the water. A fish expends little energy in support against the pull of gravity.

 

1.4.                    Fins: Fishes move through the water using their fins and body wall to push against the incompressible surrounding water. Very efficient, fast-swimming fishes, such as tuna and mackerel, supplement body movements with a vertical caudal (tail) fin that is tall and forked. The forked shape of the caudal fin reduces the surface area that could cause turbulence and interfere with the forward movement.

 

1.5.                    Arrangement of muscle bundles: The muscle bundles of most fishes are arranged in a >>, pattern. Because these muscles extend posteriorly and anteriorly in a zigzag fashion, contraction of each muscle bundle can affect a relatively large portion of the body wall.

2.    LOCOMOTION IN AMPHIBIANS:

Amphibians are tetrapods. The name is derived from the presence of four muscular limbs and feet with toes and fingers (digits). Tetrapods depend more on appendages than on the body wall for locomotion. Amphibians have a wide variety of locomotion modes.

2.1.   Locomotion in Frog: The frog's powerful hind legs are adapted for both swimming and leaping. The strong extensor muscles of the thigh contract, extending the limb and thrusting the foot against the ground or against the water. On moving from water to land or over rough ground the frog will crawl rather than leap.

 

2.2.  Locomotion in salamander: Salamanders employ a relatively unspecialized form of locomotion that is reminiscent of the undulatory waves that pass along the body of a fish. Terrestrial salamanders also move by a pattern of limb and body movements in which the alternate movement of appendages results from muscle contractions that throw the body into a curve to advance the stride of a limb.

 

3.    LOCOMOTION IN REPTILES:

 

·         Reptiles move better than amphibians because of the evolution of the skeleton. They use the method of walking and running. The general form of the reptilian skeleton is based on one inherited from ancient amphibians. They show striking adaptations for locomotion.

·         Reptiles run, crawl, climb, jump, glide, and swim.

 

4.    Locomotion in Birds:

 

·         Bird flight is the primary mode of locomotion used by most bird species in which birds take off and fly. Bird flight is one of the most complex forms of locomotion in the animal kingdom.

·         Each facet of this type of motion, including hovering, taking off, and landing, involves many complex movements. This type of locomotion demands more energy.

 

4.1. Flight: The wings of birds are adapted for different kinds of flight. However, regardless of whether a bird soars, glides, or has a rapid flapping flight, the mechanics of staying aloft are similar. Bird wings form an airfoil.

 

4.2.   Adaptation of wings for flight: The anterior margin of the wing is thicker than the posterior margin. The upper surface of the wing is slightly convex, and the lower surface is flat or slightly concave. Air passing over the wing travels farther and faster than air passing under the wing, decreasing air pressure on the upper surface of the wing and creating lift.

 

4.3.  Role of Tail of Birds: 

    The  tail of a bird serves a variety of balancing, steering, and braking functions during flight.

   

 It also enhances lift that the wings produce during low-speed flight.

   

 During horizontal flight, spreading the tail feathers increases lift at the rear of the bird and causes the head to dip for the descent.

·                     Closing the tail feathers have the opposite effect.

·                    Tilting the tail sideways turns the bird.

·                     When a bird lands, its tail deflects downward, serving as an air brake.

5.    Locomotion in  Mammals:

Mammals may have limbs that are specialized for a way of moving. They may be specialized for running, jumping, climbing, flying, or swimming. Mammals have many different modes of locomotion:

  • Mammals are noted for their diversity of modes of locomotion, or ways of moving about.
  • Some mammals that are specialized for running, such as horses and deer, have hooves on their feet.
  • Arboreal mammals typically have five fingers or toes on their hands and feet, which help them grasp the branches of trees.
  • Some mammals have evolved fins and other adaptations for aquatic environments.

5.1.   Plantigrade: In this mode of locomotion, the mammals used to walk on their soles with palm, wrist, and digits all lending to rest more or less on the ground, such as monkeys, apes, man and bear etc.

5.2.    Digitigrade: Some mammals tend to walk on their ‘digits only. They run faster than plantigrade animals. In these mammals, the first digit usually reduces or completely lost such as rabbit, rodents etc.

5.3.   Unguligrade: These mammals walk on the tips of toes modified into hoof such as deer, goat. It is the swiftest type of locomotion.