Day octopus (Octopus cyanea) hunting on the sea floor. The grouper fish surround the octopus while it hunts and waits for prey that might escape. The day octopus is found throughout the Indo-Pacific and hunts during the day. It feeds on various bivalves, fish, crabs and shrimp. Like all octopi, the day octopus has three hearts. Two pump blood to each of the two gills and the third pumps blood through the body. It can change colour according to its surroundings by dilating or contracting pigment cells called chromatophores. This acts as a form of camouflage from predators. Photographed in the Andaman Sea, Thailand.