QUADRUPED ANIMALS: CHARACTERISTICS AND EXAMPLES - BIOLOGY - 2024

The quadrupeds are those to mobilize used routinely four limbs, two previous and two subsequent. The body of this group of animals can be divided into three planes.

First, the sagittal, distinguishing two sides: right and left. Second, the transversal, which divides it into two parts; posterior and anterior. In the frontal plane two halves are differentiated; the ventral and the dorsal.

Elephant. Source: pixabay.com

Animals that have four limbs are called tetrapods. However, not all tetrapods are quadrupeds. For example, a bird has four limbs, since from an evolutionary perspective the wings are considered modified body members. However, when moving on the ground, this animal only uses two, therefore, it is bipedal.

characteristics

Limb position

Moving on all fours involves a cyclical exchange of kinetic energy and gravitational potential energy of the center of mass. The limbs of the quadrupeds work in coordination with the vertical movements of the posterior and anterior part of the body, in order to produce displacement.

In this group of animals, the head rests on the postvertebral ligaments and the muscles of the neck, causing compression of the cervical vertebrae.

As they march, the movement of the limbs causes a displacement of the body's center of mass up or down.

The function of the fore and hind legs in most quadruped animals is highly specialized. The hind limbs are used mainly as the motor of the movement, while the front limbs are the brake.

Way of walking

Quadruped animals walk in front first of the left hindquarters and then the anterior of the same side.

Next, this same sequence is repeated for the right fourths. All species in this group move in the same way and if there is any difference, it could be due to the rhythm of their strides.

Specialists say that this way of walking provides the animal with great stability while doing it. Regardless of how it moves, fast or slow, the body is supported on the ground on three legs at the same time, forming a kind of triangle.

The closer the center of gravity is to the center of gravity of the triangle formed, the greater the static stability of the animal.

Movement

In the trot alternate movements occur on the part of the limbs. If the animal moves through the gallop, the front and rear legs are raised and placed on the ground alternately and synchronously.

As you develop a higher speed, the limbs last extended less time, making stronger push-ups.

The movements carried out by each limb of quadruped animals is divided into two stages:

- Balancing. Here, the animal's leg does not make contact with the ground. This phase includes flexion of the limb, its extension and forward movement, and extension before touching the substrate.

- Support. In this stage, the limb is in continuous contact with the ground, where it slides in the opposite direction to that of the body, pushing it forward.

Examples

Dog

Peruvian dog

The legs of these animals are formed by the claws, the metacarpal pads, the inner finger or spur and the digital pad. These structures absorb shock and protect the joints and bones of the leg.

In addition, they have a carpal pad, located on each front leg. This fulfills the function of contributing to braking and maintaining balance.

The forelimbs are made up of bones: the ulna, radius, humerus, carpus, metacarpus, and phalanges. The posterior ones are made up of the femur, tibia, fibula, tarsus, metatarsal, and phalanges.

Elephant

Asian elephant

The leg is made of fibrous and fatty tissue, which acts by absorbing blows. It has elastic properties, which helps to maintain the balance of the animal. The front leg of this mammal is circular in shape, while the rear leg is slightly more oval.

Elephants use their limbs differently from other quadrupeds. These use both the front and rear to accelerate and brake, where each member acts independently.

Specialists believe that this particular use is due to its enormous size and the need for stability on the ground.

Rhino

Rhinos have small, short but powerful limbs. They have three immobile toes, with a larger circular pad spread evenly on the legs. These end in hooves, preventing the animal from sinking into the mud.

When they walk, they do so by putting more pressure on the inside of their legs. These animals can move very fast, compared to their body weight.

The white rhinoceros (Ceratotherium simum) can weigh up to 3,600 kg, yet its relatively slender limbs allow it to stand and move easily in its habitat.

This species, when it needs to flee or attack a predator, can run at approximately 40 km / h. Besides this, you could easily change the direction of your career.

Giraffe

This artiodactyl mammal has hind and forelegs about the same size. The ulna and radius of the forelimbs are articulated through the carpus, a structure similar to the carpus in humans. The leg measures 30 centimeters in diameter and the helmet measures between 10 and 15 centimeters.

The back of the hoof is low and the spur is located close to the ground, allowing the limb to support the weight of the animal.

It moves in two ways; galloping or walking. Walking makes it the same as the rest of the quadrupeds. The difference occurs when it gallops, since the giraffe moves its hind legs around the previous ones, before they move forward.

At that time, the animal counteracts the impulse of movement and remains balanced, thanks to the movements it makes with its neck and head, which go back and forth.

In short distances, the giraffe could reach a speed of 60 km / h and sustain the march at 50 km / h on longer distances.

Lion

Source: pixabay.com

The lion walks in the digitigrade position, lifting the instep and heel off the ground. This makes your ride versatile and quiet. Their legs are large and strong, with very sharp retractable claws. You can retract them when you walk, so they don't interfere with the speed of your movements.

The legs have large pads, providing protection to the toes and bones of the leg, as well as aiding in their silent walking. Despite being an animal of great strength, this feline does not have the resistance to travel long distances.

The heart of the lion represents 0.45% of its body weight, so it only allows it to reach fast and short accelerations. The walking speed is between 3 and 4 km / h and the maximum in a race could be approximately 48 to 59 km / h.

Cheetah

This feline, in its fastest race, can move at more than 104 km / h. This makes it the fastest mammal on earth. These high speeds can be achieved thanks to the fact that its limbs are thin, long and light.

In addition, it has a very flexible spine, which improves the length of each stride. Its tail also contributes to its swift movement, acting as a stabilizer. However, cheetahs can only run fast over short distances and on flat ground, without major irregularities.

During its run, the animal manages to keep its head stable. This is done through the pendulum movements of its front and rear legs, which act by balancing the general movement of the body.

Wolf

Pack of wolves.

An adult gray wolf could run faster than 60 km / h. Likewise, I could maintain a constant pace in that race at 30Km / h for 7 hours.

The incomparable resistance of this animal is part of a hunting strategy, where the herd chases a large prey until it is exhausted.

When running, the wolf fully extends its limbs. Head movements cause the center of gravity to shift back and forth with each stride. In this way, the forward thrust force is maximized, which allows the animal to move.

Camel

Camels have morphological adaptations that allow them to live in environments where food and water are often in short supply, such as mountain plateaus or deserts.

These animals have a long slender neck, their limbs are thin and long, ending in two toes that lack hooves. The camelid has a palmar pad of fat, which helps cushion the blows it may receive in that area.

Due to the characteristics of his locomotor system, his walk is characteristic, known as rhythm. In this, both legs on one side move forward at the same time and then the limbs on the other side do the same.

Antelope

Antelopes that are medium to small in size, such as the Impala and Thomson's Gazelle, are excellent jumpers and fast sprinters. The cervicabra, native to India, could run at more than 80 km / h. During that race she can jump over obstacles up to two meters high.

The jumping technique of this particular species is different from that used by the snow leopard or the cat. A cat jumps due to the rapid extension of all the joints of its hind legs.

In contrast, the antelope uses elastic energy, contained in the spinal column and the tendons of the leg. The vertebral column of the cervicabra flexes as the front and rear extremities extend. That elastic force is stored and released in the momentum of the jump.

Zebra

The zebra, like horses, supports its body weight in the third digit of its leg. Concentrating strength in the single digits allows you to achieve fast and powerful locomotion.

The downside is in balance, as this arrangement greatly limits the ability to control stability while running.

However, in its natural desert or open grassland habitat, having a fast and efficient run is more profitable for the zebra than one that is characterized by its agility and balance.

References

1. Natalie Wolchover (2012). Scientists Uncover How Dainty Rhino Feet Support Huge Bodies. Livescience. Recovered from livescience.com.
2. Timothy M. Griffin, Russell P. Main, Claire T. Farley (2004). Biomechanics of quadrupedal walking: how do four-legged animals achieve inverted pendulum-like movements ?. Journal of Experimental Biology. Recovered from jeb.biologists.org
3. Alexander, R. McN., Pond, CM, (1992). Locomotion and bone strength of the white rhinoceros Ceratotherium simum. Journal of Zoology. Rhino Resource Center. Recovered from.rhinoresourcecenter.com.
4. Wikipedia (2019). Quadruped. Recovered from en.wikipedia.org.
5. Rick Gillis, Glenn Brice and Kerrie Hoar (2011). Anatomical terms for quadrupeds. Department of Biology University of Wisconsin. Recovered from bioweb.uwlax.ed.
6. Naomi Wada (2019). Mammals' locomotion. Mammals' locomotion. Recovered from mammals-locomotion.com