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 squid is a mollusc with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting these criteria. Like all other cephalopods, squid have a distinct head, bilateral symmetry, and a mantle. They are mainly soft-bodied, like octopuses, but have a small internal skeleton in the form of a rod-like gladius or pen, made of chitin.
Deep-sea fish are fish that live in the darkness below the sunlit surface waters, that is below the epipelagic or photic zone of the sea. The lanternfish is, by far, the most common deep-sea fish. Other deep-sea fishes include the flashlight fish, cookiecutter shark, bristlemouths, anglerfish, viperfish, and some species of eelpout.
Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some bioluminescent bacteria, and terrestrial arthropods such as fireflies. In some animals, the light is bacteriogenic, produced by symbiotic bacteria such as those from the genus Vibrio; in others, it is autogenic, produced by the animals themselves.
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 pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word pelagic is derived from Ancient Greek πέλαγος (pélagos) 'open sea'. The pelagic zone can be thought of as an imaginary cylinder or water column between the surface of the sea and the bottom. Conditions in the water column change with depth: pressure increases; temperature and light decrease; salinity, oxygen, micronutrients all change. Somewhat analogous to stratification in the Earth's atmosphere, but depending on how deep the water is, the water column can be divided vertically into up to five different layers.
Bathyteuthis is the singular genus of squid in the family Bathyteuthidae, encompassing three species.
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 to 5 years.
Stauroteuthis is a genus of deepwater cirrate octopus, a cephalopod mollusk. This is the only genus in the family Stauroteuthidae, and only three species have been described in this genus.
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.
Ocythoe tuberculata, also known as the tuberculate pelagic octopus or football octopus, is a pelagic octopus. It is the only known species in the family Ocythoidae.
Opisthoteuthis californiana, also known as the flapjack octopus, or flapjack devilfish is a species of umbrella octopus.
The abyssal zone or abyssopelagic zone is a layer of the pelagic zone of the ocean. The word abyss comes from the Greek word ἄβυσσος (ábussos), meaning "bottomless". At depths of 4,000–6,000 m (13,000–20,000 ft), this zone remains in perpetual darkness. It covers 83% of the total area of the ocean and 60% of Earth's surface. The abyssal zone has temperatures around 2–3 °C (36–37 °F) through the large majority of its mass. The water pressure can reach up to 76 MPa.
The splendid lanternshark is a shark of the family Etmopteridae found in the western Pacific at depths between 120 and 210 m. Through the classification of Etmopterus species into several clades based on the positioning of their bioluminescent photophores, the splendid lanternshark can be considered a member of the Etmopterus pusillus clade.
Chaetopterus pugaporcinus, commonly known as the pigbutt worm or flying buttocks, is a species of worm first described by scientists at the Monterey Bay Aquarium Research Institute in 2007. The worm is round in shape, approximately 10 to 20 millimeters in length, and bears a strong resemblance to a disembodied pair of buttocks. Because of this, it was given a Latin species name that roughly translates to "resembling a pig's rear."
Stauroteuthis syrtensis, also known as the glowing sucker octopus or bioluminescent octopus, is a species of small pelagic octopus found at great depths in the north Atlantic Ocean. It is one of a very small number of octopuses to exhibit bioluminescence.
Bolitaena is a genus of pelagic octopods from the subfamily Bolitaeninae in the family Amphitretidae. It contains two species, a third species Bolitaena microcotyla is now regarded as a synonym of Haliphron atlanticus.
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.
Opisthoteuths massyae is an octopus living in the eastern Atlantic Ocean.
A micronekton is a group of organisms of 2 to 20 cm in size which are able to swim independently of ocean currents. The word 'nekton' is derived from the Greek νήκτον, translit. nekton, meaning "to swim", and was coined by Ernst Haeckel in 1890.
