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The present paper constructs a general ethogram for the actions of the flexible body as well as the skin displays of octopuses in the family Octopodidae. The actions of 6 sets of structures (mantle-funnel, arms, sucker-stalk, skin-web, head, and mouth) combine to produce behavioral units that involve positioning of parts leading to postures such as the flamboyant, movements of parts of the animal with relation to itself including head bob and grooming, and movements of the whole animal by both jetting in the water and crawling along the substrate. Muscular actions result in 4 key changes in skin display: (a) chromatophore expansion, (b) chromatophore contraction resulting in appearance of reflective colors such as iridophores and leucophores, (c) erection of papillae on the skin, and (d) overall postures of arms and mantle controlled by actions of the octopus muscular hydrostat. They produce appearances, including excellent camouflage, moving passing cloud and iridescent blue rings, with only a few known species-specific male visual sexual displays. Commonalities across the family suggest that, despite having flexible muscular hydrostat movement systems producing several behavioral units, simplicity of production may underlie the complexity of movement and appearance. This systematic framework allows researchers to take the next step in modeling how such diversity can be a combination of just a few variables. (PsycINFO Database Record

Subject Overview and Background Information Animals play important roles in the lives of humans. Animals have been used for centuries for work, such as in helping to plow fields, providing a means of transportation and aiding in search and rescue, and as a source of food and other products for humans. Many people have companion animals-dogs and cats are among the most popular-in their homes. Because we depend upon animals in so many ways, it is important that we, as their caretakers, understand their biology and their behavior in order to assess their health and well-being. While a normal part of responsible animal care involves preventative veterinary care, including annual exams with vaccinations and blood tests, many common injuries and illnesses can be detected just by noticing a change in the behavior of an animal. Because behavior is a primary means of communication, a change in an animal's activity level, eating habits, posture, or gait can often "tell" us something important and be a clue to detect or prevent an illness or injury. By making careful observations and developing an ethogram (a description of an animal's behavior), we can learn to recognize the range of behaviors performed by different kinds of animals as well as by different individuals of the same animal type. Through this process, we will come to understand how animals react or respond to different conditions (e.g., changes in weather) or stimuli (e.g., loud noises), and what types of behaviors might indicate that something is wrong with our animals. Sometimes symptoms of diseases or injuries are not always obvious, and detection depends on how closely we observe our animals and how well we understand their behaviors. Activity Concepts and Vocabulary Animal behavior • : A branch of biology that studies the behavior of animals. Ethogram (ee-thuh-gram) • : A description of the types of behaviors performed by the species you are studying.

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The analysis of a natural motor action is always difficult, especially when different motor programs are combined within the same interaction with the environment. We analyzed the behavior of an octopus, Abdopus sp., filmed in tidal pools in Okinawa, Japan, which used the kinematic primitives of rotation and translation of its hydrostatic arms, and combined these kinematic behaviors serially and in parallel to ‘slap’ at fish in the wild. In total, 19 slaps were analyzed. The kinematics of arm movement were measured in both external and animal-centered reference frames, while the octopus was slapping at the fish. By combining these primitives, the octopus is able to maintain flexibility while controlling only a few degrees of freedom, a concept we term ‘flexible rigidity’. This slapping action supports Flash and Hochner’s embodied organization view of motor behavior, as well as their idea that motor primitives can combine syntactically to form a complex action. The octopus’s ability to use sensory feedback from the position of a moving fish target, along with the feed-forward motor primitives, allows for the building of complex actions at dynamic equilibrium with the environment. Over all, these findings lead to a more realistic view of how a complex behavior allows an animal to coordinate with its environment.

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An octopus, Abdopus sp., can use rotation and translation of its hydrostatic arms, and combine these kinematic behaviors serially and in parallel, on different arms, to ‘slap’ at fish in the wild. Different motor programs may be used in multiple arms producing complex actions. The movements analyzed in this work show how complex the movements of the octopus, in situ, can be, furthering knowledge of this animal’s behavior, as well as furthering understanding of the structure of animal motor control. Stiffening of the flexible muscular hydrostatic arms was found to be important to both primitives of translation and rotation. By combining these kinematic primitives, the octopus is able to maintain flexibility while controlling only a few factors, or degrees of freedom, a concept we term ‘flexible rigidity’. The slapping action of the octopus of interest, Abdopus sp., therefore, gives support for Flash and Hochner’s embodied organization view of motor behavior, as well as their idea that motor primitives can combine syntactically to form a complex action. Our results suggest that the octopus’s ability to use sensory feedback from the position of a moving fish target, along with the feed-forward motor primitives, allows for the building of complex actions at dynamic equilibrium with the environment. Overall, these findings lead to a more realistic view of how a complex behavior allows an animal to coordinate with its environment.