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.
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen), usually hidden entirely under the thorax. They live in all the world's oceans, in freshwater, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers on each arm. They first appeared during the Jurassic Period.
The giant squid is a species of deep-ocean dwelling squid in the family Architeuthidae. It can grow to a tremendous size, offering an example of abyssal gigantism: recent estimates put the maximum size at around 12–13 m (39–43 ft) for females and 10 m (33 ft) for males, from the posterior fins to the tip of the two long tentacles. The mantle of the giant squid is about 2 m long, and the length of the squid excluding its tentacles rarely exceeds 5 m (16 ft). Claims of specimens measuring 20 m (66 ft) or more have not been scientifically documented.
Teuthology is the study of cephalopods. Cephalopods are members of the class Cephalopoda in the Phylum Mollusca. Some common examples of cephalopods are octopus, squid, and cuttlefish. Teuthology is a large area of study that covers cephalopod life cycles, reproduction, evolution, anatomy and taxonomy.
Cancer pagurus, commonly known as the edible crab or brown crab, is a species of crab found in the North Sea, North Atlantic Ocean, and perhaps the Mediterranean Sea. It is a robust crab of a reddish-brown colour, having an oval carapace with a characteristic "pie crust" edge and black tips to the claws. A mature adult may have a carapace width up to 25 centimetres and weigh up to 3 kilograms. C. pagurus is a nocturnal predator, targeting a range of molluscs and crustaceans. It is the subject of the largest crab fishery in Western Europe, centred on the coasts of the British Isles, with more than 60,000 tonnes caught annually.
Macrobrachium rosenbergii, also known as the giant river prawn or giant freshwater prawn, is a commercially important species of palaemonid freshwater prawn. It is found throughout the tropical and subtropical areas of the Indo-Pacific region, from India to Southeast Asia and Northern Australia. The giant freshwater prawn has also been introduced to parts of Africa, Thailand, China, Japan, New Zealand, the Americas, and the Caribbean. It is one of the biggest freshwater prawns in the world, and is widely cultivated in several countries for food. While M. rosenbergii is considered a freshwater species, the larval stage of the animal depends on brackish water. Once the individual shrimp has grown beyond the planktonic stage and becomes a juvenile, it lives entirely in fresh water.
Cephalopod intelligence is a measure of the cognitive ability of the cephalopod class of molluscs.
The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments are of Latin origin, and may be confused with terms for bones: coxa, trochanter, femur, tibia, tarsus, ischium, metatarsus, carpus, dactylus, patella.
Onykia ingens, the greater hooked squid, is a species of squid in the family Onychoteuthidae. It occurs worldwide in subantarctic oceans.
Octopus wrestling involves a diver grappling with a large octopus in shallow water and dragging it to the surface.
Pohlsepia mazonensis is a species of fossil organism with unknown affinity. Although it was originally identified as an extinct cephalopod, later studies denied that interpretation. The species is known from a single exceptionally preserved fossil discovered in the late Carboniferous (Pennsylvanian) Francis Creek Shale of the Carbondale Formation, north-east Illinois, United States.
Moroteuthopsis longimana, also known as the giant warty squid or longarm octopus squid, is a large species of hooked squid. It attains a mantle length of at least 85 cm and probably over 1.15 m. The largest complete specimen of this species, measuring 2.3 m in total length, was found in Antarctica in 2000.
All cephalopods possess flexible limbs extending from their heads and surrounding their beaks. These appendages, which function as muscular hydrostats, have been variously termed arms, legs or tentacles.
Angustidontus is a genus of predatory pelagic crustaceans from the Late Devonian and Early Carboniferous periods, classified as part of the subclass Eumalacostraca. Fossils of the genus have been recovered in relative abundance from Canada, Germany, the Czech Republic, Poland, Belarus, Ukraine and large parts of the United States, including Oklahoma, Ohio, Indiana, Kentucky, Montana, Utah, Nevada.
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.
Cephalopods, usually specifically octopuses, squids, nautiluses and cuttlefishes, are most commonly represented in popular culture in the Western world as creatures that spray ink and use their tentacles to persistently grasp at and hold onto objects or living creatures.
Pain in cephalopods is a contentious issue. Pain is a complex mental state, with a distinct perceptual quality but also associated with suffering, which is an emotional state. Because of this complexity, the presence of pain in non-human animals, or another human for that matter, cannot be determined unambiguously using observational methods, but the conclusion that animals experience pain is often inferred on the basis of likely presence of phenomenal consciousness which is deduced from comparative brain physiology as well as physical and behavioural reactions.
Paguristes eremita, the eye spot hermit crab, is a species of hermit crab in the family Diogenidae. It is found in the Mediterranean Sea.
