Some animals are able to move from place to place by means of jet propulsion. They are able to pull water from outside of their bodies, pass it over their gills to exchange gases, and direct the water back outside their bodies by way of a muscular tube called the siphon. When the water is forcefully directed the organism moves off in the opposite direction. Two examples of these organisms that use jet propulsion are Nautilus and the Octopus.
The Nautilus exhibit contains animals that have descended relatively unchanged from ancestors millions of years ago. During daylight hours these elusive creatures inhabit the deep dark depths of the reef drop-off at around 1,000 feet (about 300 meters). At night they ascend to about 200 feet (66 meters) to feed and to possibly lay their eggs. There is much that is still unknown about these secretive creatures.
The Octopus exhibit contains a Hawaiian day octopus. Day octopus are experts at camouflage, able to conceal themselves by imitating the colors, patterns and textures of their surroundings. These animals feed on a variety of items such as crabs, shrimps and marine snails. Sometimes they may even catch and eat a passing fish. At Waikīkī Aquarium the octopus are fed one or two frozen shrimp daily, and as an enrichment activity for these intelligent animals, they are trained to retrieve it from the inside of a closed jar.