They are classified by having eight legs with a soft body. They are bilaterally symmetric with two eyes on each side and a beaked mouth between their eight legs.
They are found in various habitats throughout every ocean including pelagic waters, coral reefs, and the seabed.
Their diets vary based on where they live. bottom-dwellers mainly prey on crustaceans, worms, and mollusks where open ocean octopus feed on prawns, fish and other Cephalopods.
When swimming they trail their eight legs behind them and use a siphon to expel a jet of water to propel them forward.
They have various strategies to avoid predators, they can expel ink, jet quickly through the water to evade and hide and will use camouflage.
They have very complex nervous systems and one of the best eyesight out of all ocean creatures.
They are one of the most intelligent of all the invertebrates and the most behaviorally diverse.
They can contrast their body to squeeze through very tight spaces.
All octopus are venomous but only the blue-ringed octopus is deadly to humans.
They (along with cuttlefish) have the largest brain-to-body mass ratio of all invertebrates.