Subject: Inside the hull of a small wreck a Day Octopus (Octopus cyanea) is wriggling its arms (they are not tentacles). Each arm is controlled by an independent mini-brain. These mini-brains are a cluster of nerve cells, controlled in their turn by the large central brain.
Technique: The movement of these arms happens completely soundless under water. The slimy movement sound was added in post-production in order to make the scene more realistic. Sounds and music enhance the story telling aspect in film.