Octopus relates to approximately 300 species of soft-bodied, eight-limbed molluscs of the order Octopoda. The order is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like other cephalopods, an octopus is bilaterally symmetric with two eyes and a beak, with its mouth at the center point of the eight limbs. The soft body can rapidly 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. Fishermen 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 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.
Enteroctopus is an octopus genus whose members are sometimes known as giant octopus.
The gummy shark, also known as the Australian smooth hound, flake, sweet william or smooth dog-shark, is a shark in the family Triakidae. These small to medium-sized bottom-dwelling sharks are found mostly in, but are not limited to, the area around the southern seas of Australia and is commonly baited and fished for cuisine because of its taste and market prices. According to a 2021 paper by White, Arunrugstichai & Naylorn (2021), Mustelus walkeri is the same animal as M. antarcticus. One theory is that M. walkeri is a subpopulation of M. antarcticus.
The common octopus is a mollusc belonging to the class Cephalopoda. Octopus vulgaris is the most studied of all octopus species. It is considered cosmopolitan, that is, a global species, which ranges from the eastern Atlantic, extends from the Mediterranean Sea and the southern coast of England, to the southern coast of South Africa. It also occurs off the Azores, Canary Islands, and Cape Verde Islands. The species is also common in the Western Atlantic. The common octopus hunts at dusk. Crabs, crayfish, and bivalve molluscs are preferred, although the octopus eats almost anything it can catch. It is able to change colour to blend in with its surroundings, and is able to jump upon any unwary prey that strays across its path. Using its beak, it is able to break into the shells of shelled molluscs. Training experiments have shown the common octopus can distinguish the brightness, size, shape, and horizontal or vertical orientation of objects.
Graneledone is a genus of octopuses in the family Octopodidae. The type species is Eledone verrucosaVerrill, 1881.
Alloteuthis africana, also known as the African squid, is a species of squid in the family Loliginidae. This species of squid is restricted to the Guinean province. To identify the Alloteuthis africana from other Alloteuthis family members, it is highly recommended to measure the width of the squids head and the sucker size.
Cephalopod ink is a dark-coloured or luminous ink released into water by most species of cephalopod, usually as an escape mechanism. All cephalopods, with the exception of the Nautilidae and the Cirrina, are able to release ink.
Cuttlefish or cuttles are marine molluscs of the order Sepiida. They belong to the class Cephalopoda, which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone, which is used for control of buoyancy.
Cephalopods, as active marine predators, possess sensory organs specialized for use in aquatic conditions. They have a camera-type eye which consists of an iris, a circular lens, vitreous cavity, pigment cells, and photoreceptor cells that translate light from the light-sensitive retina into nerve signals which travel along the optic nerve to the brain. For the past 140 years, the camera-type cephalopod eye has been compared with the vertebrate eye as an example of convergent evolution, where both types of organisms have independently evolved the camera-eye trait and both share similar functionality. Contention exists on whether this is truly convergent evolution or parallel evolution. Unlike the vertebrate camera eye, the cephalopods' form as invaginations of the body surface, and consequently the cornea lies over the top of the eye as opposed being a structural part of the eye. Unlike the vertebrate eye, a cephalopod eye is focused through movement, much like the lens of a camera or telescope, rather than changing shape as the lens in the human eye does. The eye is approximately spherical, as is the lens, which is fully internal.
Macroctopus maorum is known more commonly as the Maori octopus or the New Zealand octopus. They can also be known as Pinnoctopus cordiformis, is found in the waters around New Zealand and southern Australia. M. maorum is one of the largest and most aggressive octopus species living in the New Zealand and Australian waters. They feed mainly on crustaceans and fish. Although they have a short life span, the females lay thousands of eggs and are very protective of them.
Donax hanleyanus, common name the wedge clam, is a marine bivalve mollusk species in the family Donacidae, the bean clams or wedge shells. It is widely distributed throughout the sandy beaches of the Atlantic coast of South America, from Brazil to Argentina.
Aggregata is a genus of parasitic alveolates belonging to the phylum Apicomplexa.
Louise Allcock is a British researcher, best known for her work on ecology and evolution of the cephalopods of the Southern Ocean and deep sea. She is the editor of the Zoological Journal of the Linnean Society.
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 Verill's two-spot octopus, is a similar species to the Octopous 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.
Gretta T. Pecl is an Australian marine ecologist and Director of the Centre for Marine Socioecology at the University of Tasmania. She is an Australian Research Council Future Fellow and on the Editorial Board of Springer Nature's Reviews in Fish Biology and Fisheries.
Octopus oliveri, is a species of octopus found in the western Pacific Ocean off the coast of Japan, Hawaii, and Kermadec Island, in reefs and boulder coasts.
Octopus insularis is a species of octopus found off the coast of Brazil.
