Individual Based Models (IBMs) can be used to investigate emergent behaviours of groups and flocks of animals. Early uses of IBMs showed plausible looking behaviours emerging from simple rules and were used in computer generated animations and images. This type of model has since seen use simulating behaviours of a range of animals ranging from clam larvae to moose in a range of environments. The flexibility of the model allows a range of environmental parameters to be included, allowing the response of the simulated animals to the environment to be investigated. The complexity of these models can vary considerably, and a number of additions can be made to the basic IBM structure. The detail and complexity of these models is in part constrained by the availability of environmental data and in part by available data of the animals to be simulated, which can be particularly difficult to obtain in a marine environment. A planned model for the behaviour of Harbour Porpoise (Phocoena phocoena) is given as an example use of these techniques.