They get there energy from eating their prey just like us humna we get it from eating and drinking and sleeping.
by eating
An octopus uses energy to move and catch prey.
Yes, an octopus can regrow an arm that gets torn off.
It uses its legs and starts scratching it until the blue ringed octopus has no energy left. If the blue ringed octopus tries to poison it, it does nothing because the mantis shrimp has hard armor protecting it.
Of course - all living beings use energy.
Well it depends on the size of the octopus. Mostly people do die because the octopus gets lodged in the throat of the in-taker because the octopus sucks on the inside of the throat with its suckers.
Phytoplankton gets eaten by zooplankton, which gets eaten by a small fish, which gets eaten by a shark, which dies than is eaten by a crab, which is eaten by a blue ringed octopus. The blue-ringed octopus eats crab, hermit crab, shrimp, and various small fish.
By cruising around in the water looking for more food (energy).
by propulsion. the propel themselves through the water if you ride the Kraken you'd know.
The mantis shrimp can scratch up the octopus and make it lose energy. So, now the matis shrimp can defeat it.
it gets its energy from the sun.
The electrical energy gets transformed into electromagnetic (light) energy and thermal (heat) energy.
The body gets its energy when you respire. Respiration is an energy release inside a cell