Octopuses are considered to be the most intelligent invertebrates.
They use a variety of strategies to defend themselves when threatened, including camouflage, expelling ink from their siphons, hiding or moving backwards with speed.
Research has shown that octopuses have a one-of-a-kind feature since most of their nerves are located in their tentacles, which they also partially use to think.
Octopuses are social and have an impressive ability to learn and develop new skills. Some experiments have shown that octopuses have impressively good memory and learning capabilities. At a German zoo, it was discovered that an octopus had learned how to open jars full of shrimps just by watching and mimicking the behavior of the zoo’s staff. The octopus, just 5 months old, opened the jars by pressing its body on the lid and latching onto the sides of the jar with its 8 tentacles. They are so smart that an octopus named Rambo had been given a waterproof camera and was taking photographs of visitors to her tank at Kelly Tarlton's Sea Life Aquarium in New Zealand! It was trained to take photos of those who stopped by to see her. Imagine that!
In addition, it is a fact that octopuses are especially vulnerable to stress.
Unfortunately, despite concrete evidence of their intelligence and unique abilities, we treat them with particular cruelty. Not only do we recklessly overfish them, but also violently kill them by slamming them on rocks while they are still completely conscious, as this method is believed to "soften" their meat before… cooking.
Find here a very interesting research on octopuses