Lily Anne


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Animals are a diverse group of organisms that make up the kingdom known as Animalia. They are a very familiar group of organisms and are the very kingdom of life that humans belong to. In this introduction to animals we will cover the difference between vertebrate and invertebrate animals and introduce a range of animals from both groups.

The first animals are thought to have evolved over 550 million years ago. Over the last 550 million years the animal kingdom has become incredibly successful and diverse with many million species now inhabiting Earth.

The general description of an animal is a multicellular, heterotrophic organism.The term multicellular simply means that an animal is made from more than one cell. A human, for example, is made from around 30 trillion cells.

Heterotrophic means that animals are unable to make their own food and can only obtain energy by eating other organisms.  Animals are also eukaryotes because their cells contain a nucleus and organelles.

Key to an introduction to animals is the distinction between vertebrate and invertebrate animals. Vertebrate animals are those that have an internal backbone such as humans, cats and dogs. An invertebrate is any animal that doesn’t have an internal backbone. These include animals such as insects, spiders, jellyfish, crabs and even sea anemones.

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