1. Octopuses are cephalopods, a group of invertebrates that includes squids, cuttlefish, and nautilus.

2. They are the only invertebrates that can independently digest their food.

3. Octopuses are able to change color and shape to escape from danger.

4. Male octopuses can visually identify females from a great distance, and they will often court or mate with her.

5. Octopuses typically live in temperate or cool waters, but some species can survive in both warm and cold water environments.

6. Octopuses have a very large brain for their body size - they are thought to have one of the largest brains of any invertebrate animal!

7. Unlike other mollusks, octopuses do not have a hard shell - they are instead covered by a thin layer of skin that is flexible and elastic.

8. The ink used by octopuses is not just for decoration - it is also used to detect predators, navigate through the water, and create shelters from which they can shoot ink balls at enemies.

9. Female octopuses usually give birth to between 2 and 20 eggs at a time, depending on the species.

10. They can live up to 20 years in captivity and can sexually reproduce at any time of the year.