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The capacity to associate stimuli underlies many cognitive abilities, including recognition, in humans and other animals. Vertebrates process different categories of information separately and then reassemble the distilled information for unique identification, storage and recall. Invertebrates have fewer neural networks and fewer neural processing options(More)
Touch is a principal sense in all animals. It is potentially important in species of freshwater crayfish that encounter murky waters or are nocturnal. Little is known about how tactile (touch) stimuli affect exploratory behaviour under these conditions. We placed animals in different tactile situations at the start of an exploration in a dark arena and(More)
Many crayfish species inhabit murky waters or have a crepuscular lifestyle, which forces them to rely on chemical and mechanical information rather than visual input. Information on how they use one form of mechanical information-tactile cues-to explore their local environment is limited. We observed the exploratory behavior of the crayfish Cherax(More)
Periods of isolation during which animals have no social contact are common in the design of behavioral experiments. They are used, for example, to test memory and recognition responses, or to ensure a baseline condition before experimental manipulations commence. We investigated the effect of isolation periods on the aggressive behavior of matched pairs of(More)
SUMMARY 1. High-speed cinematography of the escape behaviour of freely-moving crayfish showed that the thoracic and abdominal appendages exhibit stereotyped movements in giant axon-mediated tail flips and in non-giant flips. Three distinct classes of non-giant tail flips were recognized in this study: linear, pitching and twisting flips. 2. In medial giant(More)
How does an animal adjust its motor output to generate the same movement despite changing environmental load? The neuromuscular system that controls postural movements of the crayfish abdomen has attracted interest as a system well-suited for the study of load compensation. The motor neurones and superficial muscles that control the movement of each(More)
The serial homology of arthropods, together with our ability to identify individual neurons from segment to segment, and from animal to animal, provides opportunities for studying the changes wrought by natural selection on specific neural elements when functional requirements change in different parts of the trunk. Using this concept as a guide, we studied(More)
A machine was used to impose controlled movements, closely resembling natural movements, on some of the swimmerets of crayfish with their ventral nerve cords cut between thorax and abdomen. The rhythm of the unrestrained swimmerets could be entrained to the imposed frequency. Full entrainment occurred most readily when three or four swimmerets were(More)
The five sensory modalities of humans are also found in a wide range of invertebrates. Other vertebrates have evolved additional special senses, such as the magnetic sense, which are also found in some invertebrates. However, there remain a few sensory abilities that curiously appear to be found in either vertebrates or invertebrates, but not both. For(More)