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.
A cephalopod is any member of the molluscan class Cephalopoda such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot. Fishers sometimes call cephalopods "inkfish", referring to their common ability to squirt ink. The study of cephalopods is a branch of malacology known as teuthology.
Coleoidea or Dibranchiata is one of the two subclasses of cephalopods containing all the various taxa popularly thought of as "soft-bodied" or "shell-less". Unlike its extant sister group Nautiloidea, whose members have a rigid outer shell for protection, the coleoids have at most an internal shell called cuttlebone or gladius that is used for buoyancy or as muscle anchorage. Some species, notably incirrate octopuses, have lost their cuttlebone altogether, while in some it has been replaced by a chitinous support structure. A unique trait of the group is the ability to edit their own RNA.
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 giant squid can exceed 10 metres (33 ft) in length and the colossal squid weighs 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.
Markham's storm petrel is a seabird native to the Pacific Ocean around Peru, Chile, and Ecuador. The species is named after British explorer Albert Hastings Markham, who collected the specimen on which the scientific description was based. It is a large and slender storm petrel, with a wingspan between 49 and 54 cm. Its plumage is black to sooty brown with a grayish bar that runs diagonally across the upper side of the wings. A member of the family Hydrobatidae, the northern storm petrels, the species is similar to the black storm-petrel, from which it can be difficult to distinguish.
The Limidae or file shells are members of the only family of bivalve molluscs in the order Limida. The family includes 130 living species, assigned to 10 genera. Widely distributed in all seas from shallow to deep waters, the species are usually epifaunal or nestling, with many species building byssal nests for protection. The majority of species are capable of irregular swimming by waving their long mantle tentacles.
Enteroctopus megalocyathus, also known as Patagonian red octopus (EN), Pulpo del sur (Chile) and Pulpo colorado (Argentina); is a medium-sized octopus, and the type species for the genus Enteroctopus.
Concholepas concholepas, the Chilean abalone or Peruvian tolina, is a species of large edible sea snail, a marine gastropod mollusk. Despite the superficial resemblance, C. concholepas is not a true abalone, but a member of the family Muricidae, also known as murex snails or rock snails. This species is native to the coasts of Chile and Peru, where it is called loco, pata de burro, tolina, or chanque.
The seven-arm octopus, also known as the blob octopus or sometimes called septopus, 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, also known as the big-finned jellyhead, 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.
Eledone moschata, the musky octopus, is a species of octopus belonging to the family Octopodidae.
Octopus aquaculture describes the captive-raising of octopuses and commercial sale of their meat. A complex and labor-intensive form of farming, octopus aquaculture is being driven by strong market demand in the Mediterranean and in South American and Asian countries. Annual global demand for octopus more than doubled from 1980 to 2019, from roughly 180,000 to about 370,000 tons. The supply of octopus has been constrained by overfishing in many key fisheries and proponents of farming suggest human-induced culturing could help restock natural populations. Opponents of the nascent industry argue that cephalopod intelligence and emotional capacity, as well as the solitary and carnivorous character of octopuses, make them particularly ill-suited to intensive, captive breeding. Commercial sale may stimulate market demand, hastening rather than offsetting the decline in wild stocks. An announcement that a Spanish firm would begin octopus aquaculture as early as 2022 prompted ethical and scientific controversy.
Octopus sasakii is a species of octopus found only in salt water. This species is a taxon inquirendum.
Grimpoteuthis innominata, commonly known as the small jellyhead, 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.
Microcotyle danielcarrioni is a species of monogenean, parasitic on the gills of a marine fish. It belongs to the family Microcotylidae.
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 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.
Bathypolypus sponsalis, commonly called the globose octopus, is a deep sea cephalopod that can be found in both the eastern Atlantic Ocean and the Mediterranean Sea. It possesses many morphological traits adapted to a deep sea environment, including large eggs, reduced gills, no ink sac, and subgelatinous tissues. A distinguishing factor are the relatively large reproductive organs. Their diet consists of predominantly crustaceans and molluscs, but they sometimes consume fish as well. Bathypolypus sponsalis usually dies quickly after reproduction and only spawns once in their lifetime. Sexually mature females have a mantle length of at least 34 mm and sexually mature males have a mantle length of about 24 mm. Juveniles are white and transition to dark brown then to dark purple once maturity is reached.
Octopus hubbsorum, is an octopus in the family Octopodidae. It is commonly found along tropical waters along the central Pacific Coast of Mexico. Here, they are one of the most commonly caught cephalopods and are commercially extremely important for the economy.
Méndez-Abarca F. & R. Pepe-Victoriano (2020) Invertebrados marinos del norte de Chile: guía para la identificación y mantención en cautiverio. Vol. ll. Fundación Reino Animal & ONG por la conservación de la vida salvaje. Arica, Chile. 1-85 pp.
