Cephalopods are invertebrates. Their inside organs are protected by a mantle, which consists of a thick covering of skin and muscle. Cephalopod means “head foot.” Other cephalopods include squids, cuttlefishes and chambered nautiluses.

Octopuses have a soft body and eight arms. Each arm has two rows of suction cups. An octopus uses its mantle to breathe. It has ‘mantle slits’ behind the eyes. It draws in water through the slits into the mantle. Two gills remove the oxygen from the water, then the slits close and the water is released through a tube called the “siphon.”

Octopuses use their mantle to swim. They tighten all the mantle muscles at once, squeezing a blast of water from the siphon, causing the octopus to launch forward. It can control its speed by controlling the force of the water. They can also control the direction they go. Some octopuses also use their arms to crawl across the ocean floor.

Octopuses eat many different kinds of sea creatures. They like oysters and clams. They use their suction cups to pull the shells apart and get the food inside. They also like lobsters and crabs. Octopuses have a sharp beak. They use it to break through an animal’s shell. Then it kills the animal with poison that the octopus makes in its mouth.

The octopus mother lays thousands of eggs. She guards them for weeks. When the baby octopuses are born, the eggs burst open and the tiny octopuses swim out. The mother octopus will die soon after her eggs hatch. She will never see her babies again. Many babies will be eaten by fish, birds or other creatures.

Octopuses face many dangers in the sea, but they do have ways of protecting themselves:

• Camouflage – They have special coloring to help them blend in with their surroundings.
• Hiding – The octopus can change colors which can confuse their enemies. They can also hide in holes in the rocks.
• Ink cloud – The octopus squirts a dark, inky liquid into the water and then swims away to safety.