- Bipeds. They are those animals that walk on the two lower extremities. They are mainly birds and primates. For example: hen, gorilla.
- Quadrupeds. They are those animals that walk on four limbs, which in that case are called anterior and posterior. For example: lion, dog.
There is a family of amphibians called Bipes or bipedidae that have only two legs. However, as the forelimbs are, it cannot be considered a bipedal, as it does not walk upright.
Examples of bipedal animals
- Gorilla. Herbivorous primates that live in African forests. They are the largest primates, and their genes are 97% the same as human genes. Although they use the front legs as a point of support when walking, they support their weight mainly on the back legs, and in a state of rest they sit on their back legs.
- Ostrich. Strutioniform bird (without sternum). It is characterized by its large size and for being a runner, rather than a flier. Lives on the African continent. It can have a height of up to three meters and a weight of up to 180 kg. It lives in open spaces such as deserts or savannas, where it can see potential predators and flee thanks to its great speed.
- Penguins. A flightless seabird, which is nevertheless extremely skilled as a swimmer. When on land, it walks on two legs. They live mainly in the southern hemisphere, with the exception of the Galapagos Islands. They are found in the subantarctic islands as well as in the coasts of Peru, Chile and Argentina.
- Meerkat. Mammal that lives in the African Kalahari and Namib deserts. They are small animals that weigh less than a kilogram and a maximum height of 35 cm. It usually stands on its hind legs, but it also moves on all fours, so it can also be considered a quadruped.
- Human being. In human evolution, walking on two legs gave our ancestors (hominids) certain advantages, increasing their ability to:
- Move through plains.
- Carry utensils, food, water or babies in the hands
- Scrolling between trees
- Observe the horizon above the grasses
- Chimpanzee. A primate that is genetically very close to man, so it is considered that both species have a common ancestor. The chimpanzee can walk on all fours but can also walk on two legs, which is why it is considered a biped. In fact, its upper extremities are used mainly to move between the branches of the trees.
- Hen. It is the most numerous bird on the planet because it is raised by man. They are flightless due to the artificial selection of man, that is to say that man has favored the reproduction of the specimens that could not fly. This can be evidenced by the fact that a species of wild hen (the red rooster) is capable of flight.
Examples of quadruped animals
- Lion. A feline mammal that lives in sub-Saharan Africa and northwestern India. Since it is an endangered species, many specimens live in reserves. They live in savannas and grasslands, that is, areas where their height is sufficient to be able to observe from a considerable distance and distinguish their prey.
- Elephant. They are the largest land animals. They can weigh more than 7 thousand kilograms and measure almost four meters in height, although on average they usually measure three meters. They can live up to 90 years. The legs, in addition to being servile to move, are capable of perceiving vibrations on the ground, which other elephants use to communicate.
- Dog. It is a subspecies of the wolf. There are more than 800 breeds of dog, that is, more than any other species, with significant differences in all their characteristics, from coat and size to behavior and longevity.
- Cat. Feline that has lived with humans for more than 9 thousand years. The contraction of their hind legs makes a spring effect that allows them to perform a variety of feats, such as jumps of more than three meters in height. Cats have a “righting reflex” that allows them to turn their body in the air when they fall and thus always fall on their legs, which due to their extraordinary flexibility resist falls from significant heights.
- Common hippo. Artiodactyl mammal, that is, its extremities end in even-numbered fingers. It is semi-aquatic, that is, it spends the day in the water or in the mud and only at night does it go to the land to look for herbs to eat. There is a common ancestor between hippos and cetaceans (which are whales and porpoises, among others). Their legs are stubby as they must support a great weight: the common hippo can weigh up to three tons. They also help him to run quickly for his large volume, since he can run as fast as an average human being.
- Giraffe. It is also an artiodactyl mammal. It lives in Africa and is the tallest land animal species, reaching heights of almost 6 meters. It inhabits relatively open ecosystems, such as savannas, grasslands, and open forests. Its height allows it to access acacia leaves that are out of reach of other animals. Its front and back legs are roughly the same length. It can walk and gallop.
- Horse. Perosidactyl mammal (odd toes ending in hooves). Their legs and hooves are structures that cannot be seen in any other organism. The central joint is made up of the carpal bones. Also, you have no muscles below this joint, only skin, tendons, ligaments, cartilage, bones, and a shock-absorbing horn (hoofs).
- Rhinoceros. Mammals that live in Africa and Asia. They are characterized by the horns that they have on the snout. Their legs have a more developed central finger than the others, which serves as their main support.