Octopus relates to approximately 300 species of soft-bodied, eight-limbed molluscs of the order Octopoda. The order is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like other cephalopods, an octopus is bilaterally symmetric with two eyes and a beak, with its mouth at the center point of the eight limbs. The soft body can rapidly alter its shape, enabling octopuses to squeeze through small gaps. They trail their eight appendages behind them as they swim. The siphon is used both for respiration and for locomotion, by expelling a jet of water. Octopuses have a complex nervous system and excellent sight, and are among the most intelligent and behaviourally diverse of all invertebrates.
The blue-lined octopus is one of four species of highly venomous blue-ringed octopuses. It can be found in Pacific Ocean waters that stretch all the way from Australia to Japan. It is most commonly found around intertidal rocky shores and coastal waters to a depth of 15 metres (49 ft) between southern Queensland and southern New South Wales. It is relatively small, with a mantle up to 45 millimetres (1.8 in) in length. In its relaxed state, it is a mottled yellow-brown with dark blue or black streaks covering the whole body apart from the underside of its arms, but its vibrant blue markings appear as a warning to predators when they feel threatened. Along with its other closely related species, the blue-lined octopus is regarded as one of the most dangerous animals in the sea, and its venom can be fatal to humans.
The mimic octopus is an Indo-Pacific species of octopus from the Indo-Pacific region. Like other octopuses, it uses its chromatophores to disguise itself with its background. However, it is noteworthy for being able to impersonate a wide variety of other marine animals. Although many animals mimic either their environment or other animals to avoid predation, the mimic octopus and its close relative the wunderpus are the only ones known to actively imitate a number of animals in order to elude predators.
Octopus rubescens is the most commonly occurring shallow-water octopus on much of the North American West Coast, and a ubiquitous benthic predator in these habitats. Its range extends from the southern Gulf of California at least to the Gulf of Alaska, but may also occur in the western Pacific Ocean. O. rubescens occurs intertidally to a depth of 300 m.
Octopus cyanea, also known as the big blue octopus or day octopus, is an octopus in the family Octopodidae. It occurs in both the Pacific and Indian Oceans, from Hawaii to the eastern coast of Africa. O. cyanea grows to 16 cm in mantle length with arms to at least 80 cm. This octopus was described initially by the British zoologist John Edward Gray in 1849; the type specimen was collected off Australia and is at the Natural History Museum in London.
Abdopus is a genus of octopuses in the family Octopodidae.
Pinnoctopus is a genus of octopuses in the family Octopodidae. It is of doubtful validity.
Scaeurgus is a genus of octopuses in the family Octopodidae. The species of this genus are characterized by inhabiting the upper bathyal benthic zone from temperate and tropical latitudes in all major oceans.
Amphioctopus is a genus of octopuses comprising around 16 species.
Callistoctopus macropus, also known as the Atlantic white-spotted octopus, white-spotted octopus, grass octopus or grass scuttle, is a species of octopus found in shallow areas of the Mediterranean Sea, the warmer parts of the eastern and western Atlantic Ocean, the Caribbean Sea, and the Indo-Pacific region. This octopus feeds on small organisms which lurk among the branches of corals.
Spiruroidea is a superfamily of Spirurida.
Callistoctopus ornatus is a tropical species of octopus native to the Indo-Pacific region. Other common names include white-striped octopus and night octopus, in reference to its nocturnal habits. It was previously known as Polypus ornatus. C. ornatus is edible and was recorded in a Hawaiian market in 1914 by S. S. Berry.
The white sucker is a freshwater cypriniform fish inhabiting the upper Midwest and Northeast in North America, but is also found as far south as Georgia and New Mexico in the south and west. The fish is commonly known as a "sucker" due to its fleshy, papillose lips that suck up organic matter and aufwuchs from the bottom of rivers and streams.
Pinnoctopus cordiformis is a species of octopus found around the coasts of New Zealand.
Grimpella thaumastocheir, the velvet octopus, is the only species in the monotypic genus Grimpella, in the family Octopodidae. This species has a typical body length of 200 mm. It is an found in offshore waters and is endemic to the seas off southeastern and southwestern Australia.
Octopus oliveri, is a species of octopus found in the western Pacific Ocean off the coast of Japan, Hawaii, and Kermadec Island, in reefs and boulder coasts.
Octopus insularis is a species of octopus found off the coast of Brazil.
Coreoperca kawamebari, commonly known as the Japanese perch, redfin perch, Japanese river perch, Eye-spot perch or in Anglophone parts of Japan, simply the perch, is a predatory species of the freshwater perch native to Japan and southern Korea. They are sometimes kept as pets. The Japanese perch are a member of the perch family but with the predatory feeding behaviour of the black bass (Micropterus) and bluegill.
Cassiopea ornata are one of many Cnidarian species called the upside-down jellyfish. This pelagic jellyfish primarily lives in tropical waters, off the coast of Australia in shallow lagoons and around mangrove trees. The name "upside-down jellyfish" comes from the fact that it appears to be upside-down in its natural state—resting on its bell. Its bell is a golden/brown color and the tentacles vary with different shades of yellow. While the sighting of this particular species is rare, it is usually mistaken for vegetation like the other species in genus Cassiopea.
