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 squid is a mollusc with an elongated soft body, large eyes, eight arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida. 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.
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.
Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and birds, in contrast, have a class of cells called melanocytes for coloration.
Blue-ringed octopuses, comprising the genus Hapalochlaena, are four extremely venomous species of octopus that are found in tide pools and coral reefs in the Pacific and Indian oceans, from Japan to Australia. They can be identified by their yellowish skin and characteristic blue and black rings that can change color dramatically when the animal is threatened. They eat small crustaceans, including crabs, hermit crabs, shrimp, and other small sea animals.
The Caribbean reef squid, commonly called the reef squid, is a species of small, torpedo-shaped squid with undulating fins that extend nearly the entire length of the body, approximately 20 cm in length. They are most commonly found in the Caribbean Sea in small schools. As part of the Cephalopod class of Molluscs, these organisms exhibit specific characteristics to help them in their environment, such as tentacles for movement and feeding and color pigments that reflect their behavioral conditions.
Gryllus bimaculatus is a species of cricket in the subfamily Gryllinae. Most commonly known as the two-spotted cricket, it has also been called the "African" or "Mediterranean field cricket", although its recorded distribution also includes much of Asia, including China and Indochina through to Borneo. It can be discriminated from other Gryllus species by the two dot-like marks on the base of its wings.
The common cuttlefish or European common cuttlefish is one of the largest and best-known cuttlefish species. They are a migratory species that spend the summer and spring inshore for spawning and then move to depths of 100–200 metres (330–660 ft) during autumn and winter. They grow to 49 centimetres (19 in) in mantle length and 4 kilograms (8.8 lb) in weight. Animals from subtropical seas are smaller and rarely exceed 30 centimetres (12 in) in mantle length.
The pharaoh cuttlefish is a large cuttlefish species, growing to 42 cm in mantle length and 5 kg in weight.
The Caribbean reef octopus is a coral reef marine animal. It has eight long arms that vary in length and diameter. In comparison to the arms, the mantle is large and bulky. This species is difficult to describe because it changes color and texture to blend into its surroundings, using specialised skin cells known as chromatophores. Its color range is very large; it can change from crimson to green, and bumpy to smooth. It weighs around 3.3 lb or 1.5 kg.
Cuttlefish, or cuttles, are marine molluscs of the suborder Sepiina. 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.
Macroctopus maorum is known more commonly as the Maori octopus or the New Zealand octopus. It 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.
Sepiella inermis is a species of cuttlefish in the family Sepiidae. S. inermis is indigenous to the Indo-Pacific region. In this region, Sepiella inermis is an economically important species, and is sold and eaten.
Octopus chierchiae is commonly known as the lesser Pacific striped octopus or pygmy zebra octopus. It has been proposed as a model organism for cephalopod research as it is one of the few octopus species with the ability to lay multiple egg clutches (iteroparity), compared to most octopus species that are semelparous and die after one reproductive event. This makes Octopus chierchiae a candidate for sustainable and multigenerational laboratory research.
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.
The dwarf cuttlefish (Sepia bandensis), also known as the stumpy-spined cuttlefish, is a species of cuttlefish native to the shallow coastal waters of the Central Indo-Pacific. The holotype of the species was collected from Banda Neira, Indonesia. It is common in coral reef and sandy coast habitats, usually in association with sea cucumbers and sea stars. Sepia baxteri and Sepia bartletti are possible synonyms.
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.
Abdopus capricornicus is a species of octopus in the family Octopodidae, and is often also referred to as Octopus capricornicus. This octopus is native to the Great Barrier Reef and is often found throughout the Indo-West Pacific Ocean. There are six other species of octopuses within the subgenus Abdopus with a large number of organisms not yet described. This octopus is notable for its unique body patterning through which it can change. The likely uses for this characteristic are camouflage or intraspecific communication. Other organisms in the Abdopus genus include A. horridus, A. abaculus, A. aculeatus, and A. tonganus. Individuals are capable of autotomy, sacrificing a writhing arm to a predator to distract it while making an escape.
