Contributor: Samantha Penna. Lesson ID: 11486

How many legs do you have? What if you had none, or 1,000, and no skeleton? You'd be in the largest group of creatures in the world: Invertebrates! Watch them, then find them, and then describe them!


Life Science

learning style
Kinesthetic, Visual
personality style
Grade Level
Intermediate (3-5)
Lesson Type
Quick Query

Lesson Plan - Get It!

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  • Do you have a backbone?

Feel your spine.

  • Did you know some animals don't have backbones?

Animals that don't have backbones make up 95% of the known animal population! They are everywhere!

snail on a wire

  • Did you know you are a vertebrate?

This means you have a spine. Mammals, reptiles, amphibians, birds, and fish all have spines. Some animals don't have backbones! These animals are called invertebrates.

Invertebrates do not have a backbone!

  • What don't invertebrates have?

Tell a parent or teacher.

That's right! They don't have a backbone. Push that fact into your brain and keep it there, because you will need it for the whole lesson!

During this lesson, use a pencil and paper to write down any important facts you learn during the lesson. You should have at least two facts for each example of invertebrates.


Invertebrates are everywhere! They are the insects that fly around your food at a BBQ, they are the snails that eat your mother's garden, and they are the crabs that pinch your toes at the beach.

There are so many different types of invertebrates. Insects, worms, arachnids, snails, clams, sea stars, sea urchins, coral, sponges, jellyfish, crabs, lobsters, and leeches are all examples of invertebrates!

  • Did you remember that an invertebrate is an animal without a backbone?

Great! Below are some examples of insects.

  • Do you recognize any of those insects?

Tell a parent or teacher which ones you recognize and what those insects do:

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You see insects everywhere! You see them during the day and at night.

  • What happens when you leave a light on outside at night?

Tell a parent or teacher.

  • Did you say insects fly around it?

Fantastic! Leaving a light on at night attracts insects. Insects get confused and end up flying around your lights! Insects are invertebrates. Tell a parent or teacher what the word "invertebrate" means.

Great work! You remember that invertebrates do not have backbones. All insects have things in common. They all have six jointed legs, an exoskeleton, three body parts, and lay eggs.

Jointed legs are similar to your legs. They are able to bend. An exoskeleton is a hard, outer shell that protects insects.

  • Do you know what the three body parts of an insect are?

Tell a parent or teacher. Excellent! Insects have a head, thorax, and abdomen.

Show a parent the three body parts on the ant below. The head is an obvious one! Then, move down the body until you get to the thorax. Count the legs on the ants.

  • How many legs does each ant have?

Tell a parent or teacher.

diagram of an ant

Arachnids are another type of invertebrate. They may scare you!

  • Can you name an example of an arachnid?

That's right! Spiders are arachnids. They do not have a spine.

  • How many legs does a spider have?

Tell a parent or teacher. That's right! They have eight legs. Their eight legs are jointed. This means they have joints like people do! It is almost like they have knees! Spiders lay eggs just like insects do. They also have an exoskeleton to protect their body.

  • Where can spiders be found?

Tell a parent or teacher about a time you saw a spider.

  • Where was the spider?
  • Where does a spider live?

Share all these details with a parent or teacher.

Excellent work! Spiders live in webs or in burrows, but you may find them crawling around your home or even in your learning space! The spider below isn't so scary, is it! It's fuzzy and colorful.

Spiders are very important. They eat disease-carrying insects like mosquitoes!


Crustaceans are invertebrates, too! They don't have a spine!

Crustaceans, like crabs, lobsters, shrimp, and crayfish, can be found all over the earth. Most crustaceans live in the ocean.

  • Have you ever seen a crab at the beach?
  • What about a lobster in a tank at the grocery store?

Share your story with a parent or teacher.

Crustaceans have multiple jointed legs. Jointed legs are legs that can bend. Crustaceans lay eggs.

  • Have you ever eaten crab, lobster, or shrimp?

If you did, you were eating a crustacean!


Mollusks don't have backbones, either. They are invertebrates!

Some mollusks, like snails, have shells. They use their muscular foot for moving. Snails, slugs, octopuses, squids, clams, and mussels are all examples of mollusks. Mollusks do not have bones.


  • Did you know corals are animals?

Corals are also invertebrates.

  • What is an invertebrate?

Tell a parent or teacher.

That's correct! An invertebrate does not have a backbone. Coral has an exoskeleton for protection.

Most coral gets its energy from consuming small organisms like plankton. They use the sun to get their food. Corals live in colonies. They are often found living with similar types of corals. Corals make great homes for fish in the ocean.

coral reef

Worms are also invertebrates.

  • Have you ever seen a worm?
  • What did you notice about its physical appearance?

Share your answer with a parent or teacher.

Worms have no limbs. They breathe through their skin because they don't have lungs. They also don't have brains!

  • Have you ever seen a worm in the hot sun?
  • Was that worm moving?

Tell a parent or teacher.

  • Did you know worms get paralyzed if they are out in the hot sunlight too long?

Next time you see a worm stuck out in the hot sunlight, pick it up and place it in the shade. Worms are great for the soil! They filter the earth's soil and keep it clean.


These are just some of the many examples of invertebrates. All invertebrates do not have a backbone. Some more examples of invertebrates include: jellyfish, horseshoe crabs, and sponges. Tell a parent what you know about these types of invertebrates.

  • Where can they be found?
  • What do they do?

When you are finished discussing invertebrates, move on to the next section.

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