Year 1 · Plants and animals · Section 1.3
Metamorphosis
Young and adult animals
In some animals, the young look very different from the adults. A ladybird is an example. Its life cycle begins with an egg, which hatches into a larva.
The larva has a different appearance and way of life from the adult. Before becoming an adult, it undergoes metamorphosis: a major change in body structure and way of life.
Butterflies
Butterflies, such as the cabbage white, pass through four stages:
- Egg: Laid on cabbage leaves.
- Larva (caterpillar): Eats a great deal and grows by moulting.
- Pupa: A stage in which the body changes into an adult butterfly. A butterfly pupa is also called a chrysalis; some other insects form a silk cocoon around their pupa.
- Adult (imago): Can fly and reproduce.
During metamorphosis, the body changes greatly and adult structures such as wings and antennae develop. An adult butterfly no longer grows in size and often lives for only a short time.
Frogs
The common frog also undergoes metamorphosis:
- Eggs (frogspawn): Laid in water, often in large clumps.
- Tadpole (larva): Initially has external gills, which are later replaced by internal gills.
- Metamorphosis: Hind legs appear, followed by front legs. The tail becomes shorter and lungs develop.
- Adult frog: Can live on land and exchanges gases using its lungs and skin.
Depending on conditions, a tadpole may develop into a small frog in about 12–13 weeks. It changes from an aquatic larva into a frog that can also live on land and eat small animals, including insects.
Glossary
- Cocoon
- A protective covering, often made of silk, around the pupa of some insects.
- Imago
- An adult insect. It no longer grows in size and can usually reproduce.
- Larva
- A young animal with a different body structure and often a different way of life from the adult.
- Metamorphosis
- A major change in an animal's body structure and way of life during development.
- Pupa
- An insect stage in which the animal does not feed and its body changes greatly before adulthood.
- Stages
- The phases of an animal's life cycle, such as egg, larva, pupa and adult.
Frequently asked questions
What is metamorphosis?
Metamorphosis is a major change in an animal's body structure and way of life during development.
What are the stages of a butterfly's life cycle?
Egg, larva or caterpillar, pupa and adult. The adult butterfly is also called the imago.
How does a frog change during metamorphosis?
A tadpole develops legs and lungs while its tail becomes shorter. It changes from an aquatic larva into a frog that can also live on land.