OctopusEscape Artist of the Sea

The orange paper octopus slips out between two rocks behind a puff of dark ink.

Fold 4, ages 10 to 12FOLD4AGES 10–12Fold 4 · Explorer
Ages 10–12

OctopusEscape Artist of the Sea

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The orange paper octopus squeezes its soft body through a narrow gap between two rocks.The orange paper octopus squeezes its soft body through a narrow gap between two rocks.The orange paper octopus squeezes its soft body through a narrow gap between two rocks.

Chapter 1

No Bones About It

Squeeze your arm. Can you feel the hard bone inside? An octopus has no bones at all. Its body is soft, with only a few firm parts like its hard beak. That makes it a champion escape artist.

Arms That Taste

An octopus has eight arms. Are they tentacles? No! Squid and cuttlefish have eight arms plus two long tentacles. An octopus has only arms.

An octopus's suckers can taste what they touch, as well as feel it. So an octopus can reach into a dark crack and tell what it is holding without seeing it.

The outside of an octopus. The round mantle holds its insides.
Omar An octopus can regrow a lost arm, suckers and all. What other animals can regrow a lost part?
A close-up of an orange paper octopus arm, its round suckers pressed against a seashell.
Suckers up close. Each one can grip, feel and taste.

Nerves in the Arms

The common octopus has about 500 million nerve cells, and roughly two-thirds of them are in its arms. The arms handle a lot of feeling and moving on their own.

The orange paper octopus spreads its arms like an umbrella over a small crab on the sand.
Gotcha! Some octopuses throw their arms over a crab like an umbrella.

What's for Dinner?

Octopuses are hunters. Crabs are a favorite of many. They also eat clams and other shellfish, and fish too.

Some octopuses hunt by pouncing. An octopus spreads its arms, and the web of skin between them, over a rock like a net. Then it feels underneath for anything trapped.

Mila Octopuses often leave empty shells outside the den. What could a shell pile tell you?

If the Beak Fits

In the middle of the ring of arms is the mouth. It has a sharp beak, a bit like a parrot's. The beak is the only big hard part of an octopus's body.

An octopus has no bones, so it can squeeze through any gap bigger than its beak. Its soft body stretches and flattens to follow the beak through. A fully grown giant Pacific octopus can fit through a hole about the size of a lemon.

Mila Any gap bigger than its beak is an open door. Which gaps in your home could an octopus slip through?
The underside of the orange paper octopus: eight arms in a ring, covered in suckers, with a small dark beak at the centre.
Look underneath. The beak sits right where the arms meet.
In an aquarium, the orange paper octopus twists the lid off a glass jar with a crab inside.
Lunch in a jar. Octopuses in aquariums can learn to twist off a lid.

The Great Escape

All that squeezing makes octopuses tricky to keep. Octopuses in aquariums and labs can climb right out of their tanks. Some kinds try it much more than others.

At night, a reddish-brown paper octopus crawls across the floor from an open aquarium tank toward a small drain.
Where did Inky go? Follow the wet trail.
The orange paper octopus floats beside the kelp, glowing from inside to show two small hearts, one bigger heart and thin blue lines of blood.The orange paper octopus floats beside the kelp, glowing from inside to show two small hearts, one bigger heart and thin blue lines of blood.The orange paper octopus floats beside the kelp, glowing from inside to show two small hearts, one bigger heart and thin blue lines of blood.

Chapter 2

Three Hearts and Blue Blood

You have one heart. An octopus has three! Its blood is different too. It turns blue when it carries oxygen.

Three Hearts at Work

An octopus has three hearts. Two small hearts push blood through the two gills, where it picks up oxygen. The third heart pumps that blood around the rest of the body. Octopus blood is blue when it is carrying oxygen.

Round and round. Blood goes through the gills, then all around the body.
Omar Put your hand on your chest. Feel one heart beating? An octopus would feel three!

Gills and Blue Blood

The two feathery gills are tucked inside the mantle. Water flows in over the gills, then out through a tube called the siphon.

In the common octopus, the body heart stops beating when it swims fast with a jet of water. That is one reason octopuses crawl far more than they swim.

The orange paper octopus glows from inside, showing two small hearts, one bigger heart and thin blue lines of blood.
Three hearts at once. Two small hearts by the gills, and one for the body.

A Brain Like a Donut

An octopus's brain is shaped like a donut. The tube that carries food to its stomach runs right through the hole. So every bite it swallows passes through the middle of its brain!

For its body size, the octopus has the biggest brain of any animal without a backbone.

Mila What might happen if an octopus swallowed something sharp?
A close-up of the octopus's eye, with its wide, flat pupil, looking straight out.
Eye to eye. In bright light, a common octopus's pupil narrows to a slit.
The orange paper octopus reaches one arm toward a diver's open hand.
Who's who? In one Seattle Aquarium study, giant Pacific octopuses learned to tell apart two people dressed alike.

Puzzles and Play

In lab tests, octopuses have learned to tell shapes apart to win a treat. They can find their way through simple mazes too.

In one test, octopuses were given a floating bottle. Two of them squirted water to push it away, and the current brought it back. Scientists call this play-like. They can't ask an octopus if it is having fun!

The paper octopus rests on speckled rocks, half still orange and half turned bumpy grey-brown like the rocks around it.The paper octopus rests on speckled rocks, half still orange and half turned bumpy grey-brown like the rocks around it.The paper octopus rests on speckled rocks, half still orange and half turned bumpy grey-brown like the rocks around it.

Chapter 3

Now You See Me

Could you spot an octopus on a rocky seabed? It can change its color in a fraction of a second. It can grow bumps on its skin, too. One kind can even dress up as other animals.

Coral rubble with an octopus hidden in it, its bumpy, speckled skin matching the stones around it.
Can you find the octopus? Its bumpy, speckled skin matches the stones.

Color in a Flash

An octopus can change the color and pattern of its skin in a flash. It can raise bumps and spikes, too, so it looks like rock, coral or seaweed. Most octopuses use these tricks to hide, and to send signals to other animals.

Omar An octopus can't turn invisible. So what would you look for to spot one?

How Does It Work?

Octopus skin is packed with tiny, stretchy bags of color called chromatophores. Little muscles pull a bag wide open, and its color shows. When the muscles relax, the bag shrinks back to a dot.

The bumps are called papillae. Tiny muscles push a patch of skin up into a bump or a point, a little like goosebumps.

The octopus sleeps curled up in its den as soft patches of colour drift across its skin.
Colors in its sleep. In labs, sleeping octopuses sometimes flicker with color. Scientists are still finding out why.
A striped brown-and-white mimic octopus spreads its arms wide like a lionfish on the sand.
Lionfish or octopus? A mimic octopus can spread its arms like a lionfish.

Dress-Up Champion

The mimic octopus lives in Indonesia. It can pose as other animals by changing its shape, its color and the way it moves. It swims flat like a flatfish. It can hide six arms and wave two, like a banded sea snake. Some of these animals have a venomous sting or bite, so looking like them may keep hungry fish away.

The Big Bluff

What if a hiding octopus gets found? Many kinds switch to a bold show. They turn dark and spread their arms to look bigger. This may surprise an attacker long enough for the octopus to get away.

The paper octopus is changing colour: one half is still orange and the other half is speckled grey-brown like the rocks.
Can you see the change? Half of this octopus already matches the rocks.
The orange paper octopus shoots away, leaving a dark cloud of ink in front of a curious little fish.The orange paper octopus shoots away, leaving a dark cloud of ink in front of a curious little fish.The orange paper octopus shoots away, leaving a dark cloud of ink in front of a curious little fish.

Chapter 4

The Great Getaway

Imagine you are soft all over, and a hungry fish swims close. What would you do? An octopus can squirt ink, shoot away like a jet, or dive into its den.

Squirt and Zoom

Most octopuses can squirt a cloud of dark ink when danger comes. The ink hides the octopus while it gets away. It can also zoom off by jet, squirting water out of a tube called the siphon.

How a jet works. Water fills the mantle, then squirts out of the siphon.
The orange paper octopus zooms through the water, arms trailing behind and bubbles puffing out.
Mantle first! An octopus can jet away with its arms trailing behind.

Jet Power

An octopus can point its siphon to steer. It usually travels with its round mantle in front, so it looks as if it is swimming backward! Most of the time, octopuses crawl on their arms.

Omar Ink or jet: which trick would you try first?
The orange paper octopus peeks out of its rocky den beside a small pile of empty shells.
Home, sweet den. Octopuses often leave empty shells outside, like leftovers from dinner.

Safe at Home

Most octopuses live in a den. It might be a crack in the rocks, a hole dug in the sand or an empty shell. Tight spaces keep a soft octopus safe. Some octopuses fix up their dens. They clear out the inside and pull rocks or shells across the door.

Mila Most octopuses live alone and hunt alone. Would you like a den all to yourself?

A Coconut Shelter

Some veined octopuses carry a shelter with them! The veined octopus of Indonesia digs up halves of coconut shells and carries them across the seabed. Later it fits the two halves together and hides inside.

A brown octopus with fine dark lines walks across the sand carrying two halves of a coconut shell.
Moving house. Some veined octopuses take a shelter along. This one has two coconut shells.
Hundreds of tiny see-through baby octopuses drift through sunlit water full of plankton.Hundreds of tiny see-through baby octopuses drift through sunlit water full of plankton.Hundreds of tiny see-through baby octopuses drift through sunlit water full of plankton.

Chapter 5

Big, Small and Brand New

Did you know that every octopus hatches from an egg? Some kinds grow up to be giants, and others stay tiny.

A mother octopus in her den blows water over long strings of tiny white eggs.
A mother at work. She blows fresh water over her strings of eggs.

A Mother's Long Watch

A giant Pacific octopus mother lays tens of thousands of eggs, up to about 100,000. She hangs them in long strings from the roof of her den. Then she guards them, cleans them and blows fresh water over them. She usually stops eating while she does.

Hatching Day

Looking after their eggs is the last thing most octopus mothers do. In most octopus species, the mother lays eggs only once. She dies around the time they hatch.

In many species, the tiny babies drift in the sea for weeks or months. In others, the babies look like little grown-ups and crawl away. Either way, they look after themselves from the start.

An octopus life, from egg to grown-up.
Omar Most octopuses live only about one to two years. Is that longer or shorter than you guessed?
A huge reddish, wrinkly giant Pacific octopus spreads its arms in a kelp forest beside a much smaller diver.
A true giant. A giant Pacific octopus spreads its arms near a diver.

From Giant to Tiny

The giant Pacific octopus is the largest known octopus. A grown-up one usually weighs about 45 to 65 pounds. From arm tip to arm tip, it can stretch about 7 to 13 feet. Those are normal sizes, not records!

The smallest known octopuses are only a few centimeters long when fully grown. Some weigh less than a gram! The star-sucker pygmy octopus is one of the smallest.

From Tide Pool to Trench

Drawn to scale. A common octopus is usually 1 to 3 feet long, arms and all. An eight-year-old is about 4 feet 2 inches tall.

Octopuses live in every ocean, from tide pools to the deep sea. But no octopus lives in rivers or lakes, only in the salty sea.

Mila Scientists know of about 300 kinds of octopus, and they keep finding more. Would you like to name the next one?
The orange paper octopus sits on a coral reef and waves one arm hello.The orange paper octopus sits on a coral reef and waves one arm hello.The orange paper octopus sits on a coral reef and waves one arm hello.

Octopus Quiz

  1. How many hearts does an octopus have?

    Show the answer

    Three.

  2. What color is octopus blood when it carries oxygen?

    Show the answer

    Blue.

  3. What can an octopus's suckers do, as well as feel?

    Show the answer

    Taste.

  4. What are the tiny bags of color in octopus skin called?

    Show the answer

    Chromatophores.

  5. Which octopus can pose as a lionfish?

    Show the answer

    The mimic octopus.

  6. Which octopus carries coconut shells as a shelter?

    Show the answer

    Some veined octopuses do.

A tiny octopus, about the size of a fingernail, sits in a little shell next to a pebble.A tiny octopus, about the size of a fingernail, sits in a little shell next to a pebble.A tiny octopus, about the size of a fingernail, sits in a little shell next to a pebble.

Glossary

beak
The sharp mouth part of an octopus. It is the only big hard part of its body.
chromatophore
A tiny, stretchy bag of color in octopus skin.
mantle
The round bag behind an octopus's eyes. It holds the hearts and gills.
oxygen
A gas in air and water that animals need.
papillae
Bumps and spikes an octopus can raise on its skin.
predator
An animal that hunts other animals for food.
siphon
The tube an octopus squirts water out of.
species
One kind of living thing.
The orange paper octopus stretches its eight arms out in all directions, touching shells and pebbles.The orange paper octopus stretches its eight arms out in all directions, touching shells and pebbles.The orange paper octopus stretches its eight arms out in all directions, touching shells and pebbles.

How We Know

Everything in this book was found out by someone. Here is how scientists learned a few of these things.

Contents

  1. 1No Bones About It
  2. 2Three Hearts and Blue Blood
  3. 3Now You See Me
  4. 4The Great Getaway
  5. 5Big, Small and Brand New
  6. Octopus Quiz
  7. Glossary
  8. How We Know

For grown-ups

Fold 4 is for children of about 10 to 12 who are reading on their own. Each chapter opens with a big picture and a few lines, then mixes short text with Wow! boxes, diagrams and questions from Mila and Omar, so a child can start anywhere. Harder words are in the glossary on page 37. Try the quiz on page 36 together, and read "How we know" on page 38: it shows how scientists found some of these things out, and which questions are still open. For an easier read, try Fold 3, Octopus: Eight Arms, Three Hearts; for more depth, Fold 5, Octopus: A Field Guide.

A first chapter book. Short chapters, Wow! boxes, simple diagrams, and two young guides, Mila and Omar, who ask the questions kids ask.

Ages
10–12
Trim
8 × 10 in
Pages
40
Words
2,182
Reading grade
3.9
See the printed pages

From the octopus facts episode of our video series. All six books tell this fact too.