Frank W. Grasso

How lobsters, crayfishes, and crabs locate sources of odor: current perspectives and future directions.

Olfactory orientation poses many challenges for crustaceans in marine environments. Recent behavioral experiments lead to a new understanding of the role of multiple sensory appendages, whereas application of non-invasive chemical visualization techniques and biomimetic robotics have allowed researchers to correlate the stimulus environment with behavior and to directly test proposed orientation mechanisms in decapod crustaceans.

Guidelines for the Care and Welfare of Cephalopods in Research –A consensus based on an initiative by CephRes, FELASA and the Boyd Group:

This paper is the result of an international initiative and is a first attempt to develop guidelines for the care and welfare of cephalopods (i.e. nautilus, cuttlefish, squid and octopus) following the inclusion of this Class of ∼700 known living invertebrate species in Directive 2010/63/EU. It aims to provide information for investigators, animal care committees, facility managers and animal care staff which will assist in improving both the care given to cephalopods, and the manner in which experimental procedures are carried out. Topics covered include: implications of the Directive for cephalopod research; project application requirements and the authorisation process; the application of the 3Rs principles; the need for harm-benefit assessment and severity classification. Guidelines and species-specific requirements are provided on: i. supply, capture and transport; ii. environmental characteristics and design of facilities (e.g. water quality control, lighting requirements, vibration/noise sensitivity); iii. accommodation and care (including tank design), animal handling, feeding and environmental enrichment; iv. assessment of health and welfare (e.g. monitoring biomarkers, physical and behavioural signs); v. approaches to severity assessment; vi. disease (causes, prevention and treatment); vii. scientific procedures, general anaesthesia and analgesia, methods of humane killing and confirmation of death. Sections covering risk assessment for operators and education and training requirements for carers, researchers and veterinarians are also included. Detailed aspects of care and welfare requirements for the main laboratory species currently used are summarised in Appendices. Knowledge gaps are highlighted to prompt research to enhance the evidence base for future revision of these guidelines.

The Evolution of Flexible Behavioral Repertoires in Cephalopod Molluscs

Cephalopods are a large and ancient group of marine animals with complex brains. Forms extant today are equipped with brains, sensors, and effectors that allow them not to just exist beside modern vertebrates as predators and prey; they compete fiercely with marine vertebrates at every scale from small crustaceans to sperm whales. We review the evolution of this group’s brains, learning ability and complex behavior. We outline evidence that although competition with vertebrates has left a deep impression on the brains and behavior of cephalopods, the original reorganization of their complex brains from their molluscan ancestors might have been forged in ancient seas millions of years before the advent of bony fishes.

Lévy-taxis: a novel search strategy for finding odor plumes in turbulent flow-dominated environments

Locating chemical plumes in aquatic or terrestrial environments is important for many economic, conservation, security and health related human activities. The localization process is composed mainly of two phases: finding the chemical plume and then tracking it to its source. Plume tracking has been the subject of considerable study whereas plume finding has received little attention. We address here the latter issue, where the searching agent must find the plume in a region often many times larger than the plume and devoid of the relevant chemical cues. The probability of detecting the plume not only depends on the movements of the searching agent but also on the fluid mechanical regime, shaping plume intermittency in space and time; this is a basic, general problem when exploring for ephemeral resources (e.g. moving and/or concealing targets). Here we present a bio-inspired search strategy named Levy-taxis that, under certain conditions, located odor plumes significantly faster and with a better success rate than other search strategies such as Levy walks (LW), correlated random walks (CRW) and systematic zig-zag. These results are based on computer simulations which contain, for the first time ever, digitalized real-world water flow and chemical plume instead of their theoretical model approximations. Combining elements of LW and CRW, Levy-taxis is particularly efficient for searching in flow-dominated environments: it adaptively controls the stochastic search pattern using environmental information (i.e. flow) that is available throughout the course of the search and shows correlation with the source providing the cues. This strategy finds natural application in real-world search missions, both by humans and autonomous robots, since it accomodates the stochastic nature of chemical mixing in turbulent flows. In addition, it may prove useful in the field of behavioral ecology, explaining and predicting the movement patterns of various animals searching for food or mates.

Toward the convergence: robot and lobster perspectives of tracking odors to their source in the turbulent marine environment

Biomimetic robots are often used as platforms to evaluate specific hypotheses of animal problem solving, or as existence proofs of solutions. A closely allied application of biomimetic systems is the search for constraints on problems for which human experience of the physical world (i.e., through scale mismatch or inadequate sense organs) does not provide a basis for the formulation of well constrained hypotheses. Our investigations of chemo-orientation to turbulent odor sources with Robolobster pursues both of these ends. Parallel tests with Robolobster and with real lobsters under the same conditions allow us to exclude certain chemo-orientation hypotheses, such as concentration-gradient tracking, and to statistically describe potential guidance signals available to lobsters tracking in a turbulent plume. In this paper we analyze the input-output behavior of a lobster and our robot under the same conditions to determine the extent to which the robots purely chemotactic algorithm might be incorporated in the lobster. We suggest other chemo-orientation strategies that we believe contribute to the differences between robot and lobster behavior in terms of the alternative strategies available to the American lobster.

Obstacles to Flow Produce Distinctive Patterns of Odor Dispersal on a Scale That Could be Detected by Marine Animals

Literature Cited 6. Consi, T., F. Grasso, D. Mountain, and J. Atema. 1995. Biol. Bull. 189: 23 l-232. 1. Moore, P., and J. Atema. 1991. Biol. Bull. 181: 408-4 18. 2. Dittmer, K., F. Grasso, and J. Atema. 1995. Biol. Bull. 189: 232233. 7. Grasso, F., T. Consi, D. Mountain, and J. Atema. 1996. From Animals to Animats 4: Proceedings from the 4th Int. Conf. on Adaptive Behavior. MIT Press, Cambridge, MA (In Press).

Crayfish Inspired Representation of Space via Haptic Memory in a Simulated Robotic Agent

Some species of crayfish can learn and remember environmental features by actively collecting spatial information with their antennae. We were able to qualitatively reproduce features of crayfish exploratory behavior by incorporating into a simulated robot a mapping strategy using cross-correlation of sensed environmental features (wall discontinuities). Our model collects environmental information along one continuous surface (in one dimension) to produce a representation of a two-dimensional space. The simulated robotic model can use this information to discriminate between familiar and novel environments and shows recognition of previously explored environnments. Our results support the hypothesis that crayfish can collect and use spatial information gathered haptically while exploring. Our model also predicts features of this spatial exploration strategy that can be subsequently tested in crayfish, allowing us to modify our model accordingly.

Tactile Sensing in the Octopus

All animals must have a sense of touch, if only to avoid damage. The problem is to discover how much information about their environment the animals can derive from this sense. Octopus vulgaris has proved to be a useful tool for the investigation of how much a soft-bodied invertebrate animal can derive from contacts with its environment because it learns rapidly in the laboratory. The limits of its ability to discriminate can be deduced from the results of training experiments.

Toward a Fusion Model of Feature and Spatial Tactile Memory in the Crayfish Cherax Destructor

Previous studies of the crayfish have demonstrated an ability to remember enclosure spaces and that this memory is informed by tactile information supplied by the animal’s moving antennae. Simulation and robotic studies form a suitable method for exploring central mechanisms and excluding non-viable alternatives.

Parallel Implementation of Instinctual and Learning Neural Mechanisms in a Simulated Mobile Robot.

The question of how biological learning and instinctive neural mechanisms interact with each other in the course of development to produce novel, adaptive behaviors was explored via a robotic simulation. Instinctive behavior in the agent was implemented in a hard-wired network which produced obstacle avoidance. Phototactic behavior was produced in two serially connected plastic layers. A self-organizing feature map was combined with a reinforcement learning layer to produce a learning network. The reinforcement came from an internally generated signal. Both the adaptive and fixed networks supplied motor control signals to the robot motors. The sizes of the self-organizing layer, reinforcement layer, and the complexity of the environment were varied and effects on robot phototactic efficiency and accuracy in the mature networks were measured. A significant interaction of the three independent variables was found, supporting the idea that organisms evolve distinct combinations of instinctive and plastic neural mechanisms which are tailored to the demands of the environment in which their species evolved.