tachypomp:

Image description:”Octopus marginatus hiding between two shells from East Timor. This small octopus of no more than 4-5 cm in diameter was observed on a night dive, using one nut shell and one clam shell to hide between. When the octopus felt there was no threat, it came out of the shells and using the inner parts of its tentacles, proceeded to carry the shells while pulling itself along with the outer tips of the same tentacles. Sensing any threat, the octopus clamped itself shut between the shells with amazing speed.” Credit: Nick Hobgood

“Amphioctopus marginatus, also known as the coconut octopus and veined octopus, is a medium-sized cephalopod belonging to the genus Amphioctopus. It is found in tropical waters of the western Pacific Ocean. It commonly preys upon shrimp, crabs, and clams, and displays unusual behaviour, including bipedal walking and gathering and using coconut shells and seashells for shelter. In March 2005, researchers at the University of California, Berkeley, published an article in Science in whichA. marginatus was reported to have a bipedal behavior. It is one of only two octopus species known to display such behavior, the other species being Abdopus aculeatus. According to the article, this behavior was discovered in an area off Sulawesi, Indonesia, where the sandy bottom was littered with coconut shells. The bipedal motion appears to mimic a floating coconut. Researchers from the Melbourne Museum in Australia observed the creature’s use of tools for defense, and the use of available debris to create a defensive fortress. The discovery of this behavior, observed in Bali and North Sulawesi in Indonesia between 1998 and 2008, was published in the journal Current Biology in December 2009. The researchers filmed A. marginatus collecting coconut half-shells, discarded by humans, from the sea floor, carrying them up to 20 meters (66 ft), and arranging the shells to form a spherical hiding place akin to a clamshell. Although octopuses often use foreign objects as shelter, the sophisticated behavior of A. marginatus when they select materials, carry and reassemble them, is unusually complex.”