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.
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.
Cephalopod intelligence is a measure of the cognitive ability of the cephalopod class of molluscs.
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.
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.
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.
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 to confuse predators.
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.
Fish fulfill several criteria proposed as indicating that non-human animals experience pain. These fulfilled criteria include a suitable nervous system and sensory receptors, opioid receptors and reduced responses to noxious stimuli when given analgesics and local anaesthetics, physiological changes to noxious stimuli, displaying protective motor reactions, exhibiting avoidance learning and making trade-offs between noxious stimulus avoidance and other motivational requirements.
Pain in crustaceans is a scientific debate which questions whether they experience pain or not. 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 an animal, 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.
Animal suicide is when an animal intentionally ends its own life through its actions. It implies a wide range of higher cognitive capacities that experts have been wary to ascribe to nonhuman animals such as a concept of self, death, and future intention. There is currently not enough empirical data on the subject for there to be a consensus among experts. For these reasons, the occurrence of animal suicide is controversial among academics.
Pain in invertebrates is a contentious issue. Although there are numerous definitions of pain, almost all involve two key components. First, nociception is required. This is the ability to detect noxious stimuli which evokes a reflex response that moves the entire animal, or the affected part of its body, away from the source of the stimulus. The concept of nociception does not necessarily imply any adverse, subjective feeling; it is a reflex action. The second component is the experience of "pain" itself, or suffering—i.e., the internal, emotional interpretation of the nociceptive experience. Pain is therefore a private, emotional experience. Pain cannot be directly measured in other animals, including other humans; responses to putatively painful stimuli can be measured, but not the experience itself. To address this problem when assessing the capacity of other species to experience pain, argument-by-analogy is used. This is based on the principle that if a non-human animal's responses to stimuli are similar to those of humans, it is likely to have had an analogous experience. It has been argued that if a pin is stuck in a chimpanzee's finger and they rapidly withdraw their hand, then argument-by-analogy implies that like humans, they felt pain. It has been questioned why the inference does not then follow that a cockroach experiences pain when it writhes after being stuck with a pin. This argument-by-analogy approach to the concept of pain in invertebrates has been followed by others.
Welfare biology is a proposed cross-disciplinary field of research to study the positive and negative well-being of sentient individuals in relation to their environment. Yew-Kwang Ng first advanced the field in 1995. Since then, its establishment has been advocated for by a number of writers, including philosophers, who have argued for the importance of creating the research field, particularly in relation to wild animal suffering. Some researchers have put forward examples of existing research that welfare biology could draw upon and suggested specific applications for the research's findings.
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.
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 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.
The ethics of uncertain sentience refers to questions surrounding the treatment of and moral obligations towards individuals whose sentience—the capacity to subjectively sense and feel—and resulting ability to experience pain is uncertain; the topic has been particularly discussed within the field of animal ethics, with the precautionary principle frequently invoked in response.
Jonathan Birch is a British philosopher who is an Associate Professor in the Department of Philosophy Logic and Scientific Method at the London School of Economics and Political Science. His work addresses the philosophy of biology, especially questions around the evolution of social behaviour and social norms, animal sentience, and animal welfare.
