Terrestrial locomotion

Animals move on land in many ways.

Some use legs to walk, run, or jump. Others roll their bodies. Some animals even slide on ice.

Some creatures have many legs. A millipede can have over 1,300 legs! They move them in waves.

This helps them move forward. It is fun to see how they move. How do you move on land?

Animals move on land in many ways. This is called terrestrial locomotion.

Some animals use legs to move. This is the most common way. Some animals use a sprawling posture. This means their legs are out to the side. Salamanders and many lizards do this.

Other animals have an erect posture. Their legs are directly under their bodies. Birds and mammals use this way.

Animals also have different numbers of legs. Birds are bipedal, which means they walk on two legs.

Kangaroos are also bipedal, but they move by hopping. Many insects are hexapods. This means they have six legs. Spiders have eight legs. Some millipedes have many more. One kind has over 1,300 legs!

They move their legs in waves. This is called metachronal rhythm.

Feet also look different. Humans are plantigrade. This means we walk on our heels. Cats are digitigrade. They walk on their toes. This helps them move fast and quiet.

Some animals are ungulates. They walk on the tips of their toes. Horses are one kind of ungulate.

Moving on land is a big job for living things. This is called terrestrial locomotion.

Animals have to deal with gravity pulling them down. They also have to deal with friction, which is the rubbing of surfaces. Some animals move by using legs, which is the most common way. Others move without legs by using their bodies to push. Some even move by rolling their bodies over the ground.

Legged movement works in many different ways. One part of this is posture, or how the legs support the body. Some animals use a sprawling posture. This means their upper limbs are held out to the side. Salamanders and many lizards use this way.

Other animals use an erect posture. This means their legs are placed directly under their bodies. Birds and mammals usually have this type of posture. This helps them stay active for a long time.

Animals also use different numbers of legs to move. Birds are bipedal, which means they walk on two legs.

Many mammals, like kangaroos, are also bipedal but they move by hopping. Most insects are hexapods, meaning they have six legs. Spiders are octopedal because they have eight legs. Some creatures have many more legs. A millipede called Eumillipes persephone can have more than 1,300 legs!

These many-legged animals often move their legs in waves.

Feet are shaped in special ways to help animals move. Some animals are plantigrade. This means they put their body weight on their heels. Humans, bears, and rodents are plantigrade.

Other animals are digitigrade. This means they walk on their toes. Cats and dogs are digitigrade. This helps them move quickly and quietly.

Some animals are ungulates. These animals walk on the very tips of their toes. Horses and rhinos are examples of ungulates.

Different surfaces change how animals move. On slippery ice or snow, some animals can slide. Humans use tools like ice skates or skis to slide.

Penguins and ice seals also use the slipperiness of ice to move. On steep mountains, animals need great balance. Mountain goats are very good at moving on steep, rocky sides. Some animals even move through the trees. Monkeys use their arms to swing, which is called brachiation.

Terrestrial locomotion is the science of how organisms move across land. Moving on solid ground is very different from moving through water or air. On land, animals must deal with much stronger gravity pulling them down. They also experience friction, which is the resistance caused by surfaces rubbing together.

Evolution has driven many aquatic organisms to adapt to these land environments over millions of years. Scientists study these movements to understand how life changes and survives in different habitats.

Taxonomy, the science of classifying life, identifies three basic forms of land movement. The first is legged locomotion, which uses appendages like arms or legs. The second is limbless locomotion, where an animal uses its whole body to push forward. The third is rolling, where an organism rotates its body over a surface.

Some animals even use specialized methods for specific environments. For example, snakes may use sidewinding to move across loose sand. Other animals might use sliding on ice or snow to save energy.

Legged locomotion is the most common method for vertebrates and arthropods. A key part of this is posture, or how the legs support the body weight. There are three main vertebrate postures: sprawling, semi-erect, and fully erect.

Sprawling is the most primitive posture, where limbs are held out to the sides. Salamanders and most reptiles use this style. Semi-erect posture is an elevated version of sprawling, often seen in large lizards. Finally, mammals and birds use a fully erect posture. In this stance, legs are placed directly beneath the body. This helps animals stay active for long periods.

Animals also vary greatly in the number of legs they use. Birds are exclusively bipedal, meaning they move on two legs. Many mammals are also bipedal, though some, like kangaroos, move by hopping.

Most terrestrial vertebrates are quadrupedal, using four limbs. Insects belong to a group called hexapods because they typically have six legs. Spiders are octopedal, using eight legs for movement. Some invertebrates have many more. Centipedes can have over 200 legs. The millipede Eumillipes persephone can have more than 1,300 legs!

These many-legged creatures often move using a metachronal rhythm, which looks like waves of motion.

Foot structure is another vital part of how animals move. Tetrapods, a group including most land vertebrates, have legs with internal bones and three main joints: the shoulder, the knee, and the ankle. The way an animal places its weight on its feet varies. Plantigrade animals, such as humans and bears, place their weight on their heels for stability.

Digitigrade animals, like cats and dogs, walk on their toes. This helps them move quickly and quietly by acting like a spring. Finally, ungulates, such as horses, walk on the fused tips of their toes. This allows for efficient movement across large distances.

Environment and terrain dictate which locomotive styles are successful. On slippery surfaces like ice, animals can use sliding to move. Humans use tools like ice skates or skis to assist this.

In the trees, some monkeys use brachiation, which is swinging using their arms as the main mover. Other animals must possess sure-footedness to navigate steep, irregular mountainsides. Mountain goats are famous for this agility. Even the way animals carry their young can change their movement. Marsupials use pouches, while other species may carry young on their backs.

Locomotion is deeply connected to the broader systems of biology and physics. It involves the interaction between an organism's anatomy and the physical forces of its world. Whether it is a dung beetle rolling a ball or a velvet worm using many stubby legs, movement is a survival tool.

Understanding these diverse methods helps scientists map the history of life on Earth. Every gait and every foot shape tells a story of adaptation to the physical world.