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 centre 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.
The Bolitaeninae are a subfamily, in the family Amphitretidae, of small, common pelagic octopuses found in all tropical and temperate oceans of the world. The taxonomy of this taxon is not entirely certain; recent research suggests just two genera exist, Bolitaena and Japetella, both of which are thought to be monotypic by some authorities and under this view, the family would represent two very similar species: Bolitaena pygmaea and Japetella diaphana. However, currently a second species of Bolitaena, B. massyae is also recognised.
Kiwa hirsuta is a crustacean discovered in 2005 in the South Pacific Ocean. This decapod, which is approximately 15 cm (5.9 in) long, is notable for the quantity of silky blond setae covering its pereiopods. Its discoverers dubbed it the "yeti lobster" or "yeti crab".
The giant Pacific octopus, also known as the North Pacific giant octopus, is a large marine cephalopod belonging to the genus Enteroctopus and Enteroctopodidae family. Its spatial distribution encompasses much of the coastal North Pacific, from the Mexican state of Baja California, north along the United States' West Coast, and British Columbia, Canada; across the northern Pacific to the Russian Far East, south to the East China Sea, the Yellow Sea, the Sea of Japan, Japan's Pacific east coast, and around the Korean Peninsula. It can be found from the intertidal zone down to 2,000 m (6,600 ft), and is best-adapted to colder, oxygen- and nutrient-rich waters. It is the largest octopus species on earth and can often be found in aquariums and research facilities in addition to the ocean. E. dofleini play an important role in maintaining the health and biodiversity of deep sea ecosystems, cognitive research, and the fishing industry.
The Atlantic pygmy octopus, also known as the small-egg Caribbean pygmy octopus, is a small species of octopus in the order Octopoda. Fully grown, this cephalopod reaches a mantle length of 4.5 cm with arms up to 9 cm long. They are known for being intelligent creatures with keen senses, particularly good sight.
Incirrata is a suborder of the order Octopoda. The suborder contains the classic "benthic octopuses," as well as many pelagic octopus families, including the paper nautiluses. The incirrate octopuses are distinguished from the cirrate octopuses by the absence in the former of the "cirri" filaments for which the cirrates are named, as well as by the lack of paired swimming fins on the head, and lack of a small internal shell.
Gonatus onyx is in the class Cephalopoda and in the phylum Mollusca. It is also known as the clawed arm hook squid or the black-eyed squid. It got these names from the characteristic black eye and from its two arms with clawed hooks on the end that extend a bit further than the other arms. It is a squid in the family Gonatidae, found most commonly in the northern Pacific Ocean from Japan to California. They are one of the most abundant cephalopods off the coast of California, mostly found at deeper depths, rising during the day most likely to feed.
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.
Cerithium litteratum is a species of sea snail, a marine gastropod mollusk in the family Cerithiidae.
Octopus tetricus, the gloomy octopus or the common Sydney octopus, is a species of octopus from the subtropical waters of eastern Australia and New Zealand. O.tetricus belongs to the Octopus vulgaris species group and is a commercially prized species. All species within the O. vulgaris group are similar in morphology. The English translation of O. tetricus (Latin) is 'the gloomy octopus'.
Bathypolypus arcticus, the North Atlantic octopus, deep sea octopus or spoonarm octopus is a small species of demersal octopus of the North Atlantic. It is usually found at depths of 200 to 600 m (660–1,970 ft) where the temperature is between 2 and 6 °C (36–43 °F).
Megaleledonidae is a family of octopuses in the superfamily Octopodoidea. It was formerly placed in the family Octopodidae sensu lato as the subfamily Megaleledoninae but more recent studies have raised this taxon as a valid family. Megaleledonidae contains about 43 species in 12 genera.
Wunderpus photogenicus, the wunderpus octopus, is a small-bodied species of octopus with distinct white and rusty brown coloration. 'Wunderpus' from German “wunder” meaning ‘marvel or wonder’.
Octopus bimaculatus, commonly referred to as Verrill's two-spot octopus, is a similar species to the Octopus bimaculoides, a species it is often mistaken for. The two can be distinguished by the difference in the blue and black chain-like pattern of the ocelli. O. bimaculatus hunt and feed on a diverse number of benthic organisms that also reside off the coast of Southern California. Once the octopus reaches sexual maturity, it shortly dies after mating, which is approximately 12–18 months after hatching. Embryonic development tends to be rapid due to this short lifespan of these organisms.
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.
Octopus californicus is an octopus in the family Octopodidae. It is provisionally assigned to the genus Octopus, but some scholars have concluded it belongs in other genera. O. californicus was first documented by S. Stillman Berry in 1911.
Octopus conispadiceus is a species of long-ligula octopus, provisionally placed in the genus Octopus. It was first described by Madoka Sasaki in 1917 based on specimens bought at a fish market in Sapporo, Japan.
