Word Origin
The word animal comes from the Latin word animalis, which means “having breath” or “living being.” It is related to the Latin word anima, meaning “breath,” “soul,” or “life.” In ancient times, people believed that breathing was one of the clearest signs that a creature was alive. Today the word animal refers to members of the biological kingdom Animalia, a group of living organisms that move, eat food, grow, and reproduce.
Kingdom
Animalia
Class
There are 107 classes in 24 phyla in the Animal kingdom.
Species
Approximately 1.5 million animal species have been formally described, with a possible total number of over 8 million different species.
Wild Animals and Domesticated Animals
Wild animals live in natural environments such as forests, grasslands, deserts, mountains, oceans, and wetlands. They find their own food, build shelters, avoid predators, and survive without human care. Lions, elephants, wolves, penguins, and sea turtles are all examples of wild animals.
Domesticated animals are animals that have been bred and cared for by people over many generations. These animals often live alongside humans and depend on people for food, shelter, and protection. Dogs, cats, horses, cattle, sheep, and chickens are common examples of domesticated animals.
While some domesticated animals may live outdoors, they are different from wild animals because they have adapted to living with people. Wild animals, on the other hand, remain part of natural ecosystems and play important roles in maintaining healthy habitats and ecosystems around the world.
Animal Categories
Scientists place animals in the biological kingdom Animalia. Animals are living organisms that can move, eat food, grow, and reproduce. Unlike plants, animals cannot make their own food using sunlight. Instead, animals must get energy by eating plants, other animals, or both. This need to find food influences how animals behave, where they live, and how they survive in different environments.
Members of the biological kingdom Animalia are classified into many other groups based on their physical characteristics, body structure, and evolutionary history. These groups help us better understand how animals are related to one another and how they live in different ecosystems.
Vertebrates and Invertebrates
Animals are commonly divided into two broad categories: vertebrates, which have a backbone, and invertebrates, which do not. Vertebrates include familiar groups such as mammals, birds, reptiles, amphibians, and fish, all of which share an internal skeleton and more complex body structures. Invertebrates make up the vast majority of animal life on Earth and include many different groups, the most diverse of which are insects.
History
Animal life has existed on Earth for a very long time. The earliest animals appeared in the oceans more than 500 million years ago, long before humans existed. Over time, animals evolved into many different forms. Some adapted to life on land, developing legs and lungs. Others evolved wings and took to the air. Many remained in the oceans, where some species grew larger than any animals that have ever lived on land.
Ecosystems
An ecosystem is a place where living organisms (plants, animals, and microbes) interact with each other and with their physical environment (sunlight, soil and water). These systems support life on this planet.
In the animal world, ecosystem predators help control animal populations. Herbivores eat plants and shape vegetation. Pollinators help many plants reproduce by moving pollen from flower to flower. Even small creatures such as insects help recycle nutrients and keep ecosystems functioning.
This incredible variety of life is known as biodiversity. Biodiversity helps ecosystems stay strong and resilient. When many different species live together in a habitat, the ecosystem is better able to recover from changes such as storms, droughts, or disease.
Ecosystems are important to humans. They provide clean air, clean water, and fertile soil. Many crops that people depend on rely on animals for pollination or seed dispersal. Forests, wetlands, oceans, and grasslands all depend on complex relationships between animals and plant.
Animal Habitats
A habitat is an area within an ecosystem where wild animals, plants, and other organisms live, grow, and reproduce.
There are many different types of habitats, including oceans, forests, grasslands, wetlands, deserts, mountains, and polar regions.
You can think of a habitat as a neighborhood within an ecosystem. A habitat is the specific place where an organism lives, while an ecosystem is the larger community where living things interact with each other and their environment.
Animal Conservation | Protecting Wildlife
Caring about animals is not only about protecting them, it is also about protecting the natural systems they inhabit that support life on Earth, including human life.
When animal populations decline or habitats are damaged, ecosystems can become unstable.
Learning about animals helps us understand why conservation is important and why the preservation of wildlife is necessary for the future of the planet.
Image: Hippos are large land mammals. They share a common ancestor with whales and porpoises, and are believed to have evolved around 55 million years ago.
Interesting Animal Facts
- Millions of Animal Species
Scientists estimate there are more than 8.7 million species of animals on Earth, although only about 1.5 million species have been formally described. - Insects Are the Most Diverse Animals
Insects make up the largest group of animals. Scientists have identified over one million insect species, which is more than half of all known animal species. - Mammals Are a Small Group
There are about 6,500 species of mammals worldwide, a tiny fraction compared with insects and other invertebrates. - Birds Are Highly Diverse
Scientists recognize roughly 11,000 species of birds, found on every continent and in nearly every type of habitat. - The Largest Animal on Earth
The blue whale is the largest animal ever known to live on Earth. It can grow to over 100 feet (30 meters) long and weigh more than 200 tons. - The Fastest Land Animal
The cheetah is the fastest land animal and can reach speeds of about 60–70 miles per hour (97–113 km/h) in short bursts. - The Largest Land Animal
The African elephant is the largest land animal. Adult males can weigh over 13,000 pounds (6,000 kg). - The Longest Migration
Some animals travel enormous distances. The Arctic tern makes the longest migration of any animal, traveling more than 40,000 miles (64,000 km) each year between the Arctic and Antarctica.
