An octopus is a soft-bodied, eight-limbed mollusc of the order Octopoda. The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like other cephalopods, an octopus is bilaterally symmetric with two eyes and a beaked mouth at the center point of the eight limbs. The soft body can radically 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.
Grimpoteuthis is a genus of pelagic cirrate (finned) octopods known as the dumbo octopuses. The name "dumbo" originates from their resemblance to the title character of Disney's 1941 film Dumbo, having a prominent ear-like fin which extends from the mantle above each eye. There are 17 species recognized in the genus. Prey include crustaceans, bivalves, worms and copepods. The average life span of various Grimpoteuthis species is 3 to 5 years.
Luteuthis dentatus, also known as Lu's jellyhead, is a medium-sized species of cirrate octopus found in the southwestern Pacific, originally described by Steve O'Shea.
Umbrella octopuses are a group of pelagic octopuses. Umbrella octopuses are characterized by a web of skin between the arms, causing them to somewhat resemble an opened umbrella when the arms are spread.
Cirrina or Cirrata is a suborder and one of the two main divisions of octopuses. Cirrate octopuses have a small, internal shell and two fins on their head, while their sister suborder Incirrina has neither. The fins of cirrate octopods are associated with a unique cartilage-like shell in a shell sac. In cross-section, the fins have distinct proximal and distal regions, both of which are covered by a thin surface sheath of muscle.
Cephalopods, which include squids and octopuses, vary enormously in size. The smallest are only about 1 centimetre (0.39 in) long and weigh less than 1 gram (0.035 oz) at maturity, while the largest—the giant and colossal squids—can exceed 10 metres (33 ft) in length and weigh close to half a tonne (1,100 lb), making them the largest living invertebrates. Living species range in mass more than three-billion-fold, or across nine orders of magnitude, from the lightest hatchlings to the heaviest adults. Certain cephalopod species are also noted for having individual body parts of exceptional size. The giant and colossal squids, for example, have the largest known eyes among living animals.
The seven-arm octopus is one of the two largest known species of octopus; the largest specimen ever discovered had an estimated total length of 3.5 m (11 ft) and mass of 75 kg (165 lb). The only other similarly large extant species is the giant Pacific octopus, Enteroctopus dofleini.
Cirroteuthis muelleri was the first cirrate octopus species to be scientifically described. It is closely related to the genus Cirrothauma within the family Cirroteuthidae. At present the genus contains a single recognized species restricted to the Arctic Ocean and northern basins of the Atlantic and Pacific, but other species may be present in the southern hemisphere.
Enteroctopus zealandicus, also known as the yellow octopus, is a large octopus of the genus Enteroctopus. It is endemic to the waters surrounding New Zealand.
Pinnoctopus cordiformis is a species of octopus found around the coasts of New Zealand. It is one of the most common species of octopus in the country.
Vulcanolepas osheai, commonly referred to as O'Shea's vent barnacle, is a stalked barnacle of the family Neolepadidae. This species is endemic to New Zealand.
Luteuthis is a small genus of cirrate octopuses currently placed in the family Opisthoteuthidae. There are two species classified in this genus one from waters west of New Zealand and the other from the South China Sea.
Grimpoteuthis abyssicola is a species of small deep-sea octopus known from two specimens. The holotype specimen was a female collected on the Lord Howe Rise, between 3154 and 3180 meters depth. A second specimen was collected on the continental slope of south-eastern Australia between 2821 and 2687 m depth. While the organism has not been formally assigned a vernacular name, it has been proposed to be referred to commonly as the Angle-shelled dumbo octopus.
Grimpoteuthis innominata is a species of small, pelagic octopus described by Steve O'Shea in 1999 from two specimens, however several further specimens have since been identified. The genus Enigmateuthis was described to contain this species when described, but Martin Collins placed the species in the genus Grimpoteuthis due to uncertainty regarding the type specimen of Grimpoteuthis.
Opisthoteuthis calypso or calypso flapjack octopus is a species of genus Opisthoteuthis, which are known as the cirrate octopuses. Octopuses in this genus are known as the flapjack octopuses and can be found in a variety of oceans across the world.
Opisthoteuthis agassizii, known as the Agassiz's flapjack octopus, is a lesser-known, deep-sea octopus first described in 1883 by Addison E. Verrill.
Opisthoteuthis bruuni is a species of finned cirrate octopus found along the western coast of South America. Their tissue is almost jelly-like, and they have short, round bodies.
Grimpoteuthis angularis is a species of octopus in the family Opisthoteuthidae. It was first described by Tristan J Verhoeff and Steve O'Shea in 2022, based on a single specimen found in New Zealand.
Grimpoteuthis greeni is a dumbo octopus found in deep waters off southern Australia. The species was initially described from three specimens, with a further three specimens identified since then.
