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.
The vampire squid is a small cephalopod found throughout temperate and tropical oceans in extreme deep sea conditions. The vampire squid uses its bioluminescent organs and its unique oxygen metabolism to thrive in the parts of the ocean with the lowest concentrations of oxygen. It has two long retractile filaments, located between the first two pairs of arms on its dorsal side, which distinguish it from both octopuses and squids, and places it in its own order, Vampyromorphida, although its closest relatives are octopods. As a phylogenetic relict, it is the only known surviving member of its order.
Bigfin squids are a group of rarely seen cephalopods with a distinctive morphology. They are placed in the genus Magnapinna and family Magnapinnidae. Although the family was described only from larval, paralarval, and juvenile specimens, numerous video observations of much larger squid with similar morphology are assumed to be adult specimens of the same family.
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 two prominent ear-like fins which extend 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 3–5 years.
The California two-spot octopus, often simply called a "bimac", is an octopus species native to many parts of the Pacific Ocean including the coast of California. One can identify the species by the circular blue eyespots on each side of its head. Bimacs usually live to be about two years old. They are closely related to Verrill's two-spot octopus. In 2015, the genome was sequenced.
Kiwa is a genus of marine decapods living at deep-sea hydrothermal vents and cold seeps. The animals are commonly referred to as "yeti lobsters" or "yeti crabs”, after the legendary yeti, because of their "hairy" or bristly appearance. The genus is placed in its own family, Kiwaidae, in the superfamily Chirostyloidea. The genus Kiwa is named after the god of shellfish in Polynesian mythology.
The common blanket octopus or violet blanket octopus is a large octopus of the family Tremoctopodidae found worldwide in the epipelagic zone of warm seas. The degree of sexual dimorphism in this species is very high, with females growing up to two meters in length, whereas males grow to about 2.4 cm. The first live specimen of a male was not seen until 2002 off the Great Barrier Reef. Individual weights of males and females differ by a factor of about 10,000 and potentially more.
Orectolobus reticulatus, the network wobbegong, is a recently described species of carpet shark found in relatively shallow waters off Kimberley and Darwin in north-western Australia. With a known maximum length of only 52.3 centimetres (20.6 in), it may be the smallest species of wobbegong. Until its description in 2008, it had been confused with the northern wobbegong. The network wobbegong has a short snout, broad head, elongated body, and two dorsal fins, with the first being slightly larger than the second. Its body is grayish brown with darker brown markings and a pale yellow underbelly. The network wobbegong lives in shallow waters along reefy bottoms.
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.
Aggregata is a genus of parasitic alveolates belonging to the phylum Apicomplexa.
The curled octopus, also known as the horned octopus, lesser octopus or northern octopus, is a species of cephalopod found in the northeast Atlantic, ranging from Norway to the Mediterranean, including the British Isles. The total length of an adult is around 50 cm, but their arms are often tightly curled. It immobilises and eats large crustaceans by drilling a hole through their shell. It is mainly by-catch in commercial fisheries of the north eastern Atlantic and Mediterranean, where the common octopus is the preferred species.
Eledone gaucha is a species of octopus from the southern Atlantic Ocean. It is a predator of fish, crabs, lobsters and molluscs.
Octopus maya, known colloquially as the Mexican four-eyed octopus, is a shallow water octopus that can be found in the tropical Western Atlantic Ocean. It is common to sea grass prairies and coral formations. The species was initially discovered in an octopus fishery in Campeche Mexico, where its close external resemblance to Octopus vulgaris led to its mistaken grouping with the other species. O. maya makes up 80% of octopus catch in the Yucatán Peninsula, while O. vulgaris makes up the remaining 20%.
The larger Pacific striped octopus (LPSO), or Harlequin octopus, is a species of octopus known for its intelligence and gregarious nature. The species was first documented in the 1970s and, being fairly new to scientific observation, has yet to be scientifically described. Because of this, LPSO has no official scientific name. Unlike other octopus species which are normally solitary, the LPSO has been reported as forming groups of up to 40 individuals. While most octopuses are cannibalistic and have to exercise extreme caution while mating, these octopuses mate with their ventral sides touching, pressing their beaks and suckers together in an intimate embrace. The LPSO has presented many behaviors that differ from most species of octopus, including intimate mating behaviors, formation of social communities, unusual hunting behavior, and the ability to reproduce multiple times throughout their life. The LPSO has been found to favor the tropical waters of the Eastern Pacific.
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.
Octopus insularis is a species of octopus described in 2008 from individuals found off the coast of Brazil, with a potentially much larger range.
Opisthoteuthis agassizii is a lesser-known, deep-sea octopus first described in 1883 by Addison E. Verrill.
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.
Opisthoteuths massyae is an octopus living in the eastern Atlantic Ocean.
