Octopuses have a robust muscular tube in their body called a siphon. An octopus uses it to blast water and can even swim backwards. They can also crawl along the ocean floor and pull their arms into small openings to take in food. Octopus ink contains a chemical compound called tyrosinase that helps to control the production of melanin. Tyrosinase, when sprayed in the eyes, can cause the predator to go temporarily blind.