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Look at the similarities and differences between how plants, insects, and mammals grow.
Did you know that a giant, tall oak tree and a tiny, fluttering butterfly both started their lives as something small enough to fit on your fingernail?
Every living thing goes through a life cycle. This is the series of changes a living thing goes through from the beginning of its life until it is an adult. Plants, insects, and mammals all have life cycles, but they don't look the same! A plant starts as a tiny seed. An insect might start as a tiny egg. A mammal, like a dog or a human, usually starts as a baby born from its mother. Even though they start differently, they all have one thing in common: they grow, change, and eventually make new life.
Quick Check
What do we call the series of changes a living thing goes through during its life?
Answer
A life cycle.
Plants and animals grow in different ways. Most plants follow main stages: seed, sprout, seedling, and adult plant. Animals are a bit more diverse! Some animals, like birds and butterflies, hatch from eggs. Other animals, like kittens and elephants, are born live, which means they come out of their mother's body looking like tiny versions of the adults. Whether they hatch or are born live, all animals need food, water, and air to grow into adults.
Let's look at the steps of a sunflower: 1. Seed: A small seed is planted in the soil. 2. Sprout: Roots grow down and a tiny green stem grows up. 3. Seedling: The plant grows leaves and gets taller. 4. Adult: The plant grows a big yellow flower and makes new seeds.
Quick Check
Do all animals hatch from eggs?
Answer
No, some animals (mammals) are born live.
Why do life cycles keep going? The most important part of being an adult is reproduction. This is a big word that means making new living things. An adult sunflower makes seeds. An adult butterfly lays eggs. An adult dog has puppies. By making babies or seeds, the living thing ensures that its kind will keep living on Earth even after the adult is gone. This turns the 'line' of life into a 'circle' that never ends!
Insects like butterflies go through a big change called metamorphosis: 1. Egg: The mother lays a tiny egg on a leaf. 2. Larva: A caterpillar hatches and eats a lot! 3. Pupa: The caterpillar builds a hard shell (chrysalis). 4. Adult: A butterfly comes out, flies away, and lays new eggs.
How is a bean plant like a human? 1. Start: The bean is a seed; the human is a baby. 2. Growth: The bean gets leaves; the human grows taller and learns to walk. 3. Adult: The bean plant grows pods with new beans; the human grows up and can have their own children. Both use reproduction to start the cycle over!
What is the first stage of most plant life cycles?
Which of these animals is born live (not from an egg)?
The main goal of an adult in a life cycle is to reproduce (make new life).
Review Tomorrow
Tomorrow, try to remember the 4 stages of a plant's life cycle: Seed, Sprout, Seedling, and Adult.
Practice Activity
Go outside or look at a book and find one animal that hatches from an egg and one animal that is born live!