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Hermit crabs use gastropod shells to protect their bodies and developing eggs; an inadequate supply of shells of the appropriate size will, therefore, adversely affect their growth, fecundity and longevity. Since the supply of shells is commonly limited, mechanisms that help to reduce these adverse effects will be selectively advantageous. In Pagurus bernhardus it is suggested that two mechanisms have evolved in this respect: larval settlement is encouraged in the littoral zone where gastropod species are diverse and numerous and where the youngest hermits will find growth potentially unrestricted; and females breed within their first year of life and at a size substantially below that which could be attained in the shells commonly available to them. This ‘precocious’ breeding is suggested to be an adaptation enabling hermits to overcome the problems of shell-limitation, since it frees females of the need to attain a specific age or size before reproducing - a situation which would be perilous when large shells are scarce. Males of a similar age are freed from competition for the larger shells as a result of this strategy, since the growth of the females is suppressed while they are ovigerous.

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Dispersion in a littoral population of Pagurus bernhardus in south-west England is shown to be random, with members demonstrating no evidence of site attachment. Movement patterns within the population are shown to be asynchronous and random, and to be dictated by the quantity and quality of each individual's shell contacts. These, in turn, affect the time that individuals spend within the habitat. This implies that population dynamics and residence times are so influenced by the availability of suitable empty gastropod shells that movement and migration in hermit crabs should be regarded as resource-dependent phenomena.

In this paper we will establish the need for communication between organisations involved in the fight against counterfeiting crime. We will also examine the paradox in providing information that could serve the criminal as well as those attempting to protect themselves from criminal activity.Counterfeiting is estimated to account for over 5% of world trade. It is a global operation with no respect for international borders. It is increasingly sophisticated and increasingly the province of organised crime, which applies the techniques developed for drug distribution to the production and distribution of counterfeit articles. To fight this crime there is an increasing plethora of authenticating features and technologies available. Many companies do not recognise the problem and the number of anticounterfeit technologies can be confusing for potential users. There is therefore a need for information about them, their comparative characteristics, to be easily available. At present there is inadequate communication between those who develop and produce anti-counterfeiting devices and those who use them, notwithstanding the marketing efforts of the former. Communication which stimulates and encourages the spread of information between those engaged in-the fight against counterfeit crime can only help in that fight.But what we term 'the communication paradox' requires circumspection and care in the content and the distribution of such information. The communication paradox is that the better the channels ofcominunication, the easier it isfor criminals to get hold ofthat information. The challenge is to institute communications which are effective but restrictive. More communication of information between those engaged in counterfeit deteffence will enhance individual companies' and organisations' anticounterfeit efforts and thus contribute to an overall improvement in the fight against counterfeit crime. INTRODUCTIONThis is a technical conference. Probably every paper following this one will present information of a technical or scientific nature about devices which use optical techniques to deter counterfeiters. This paper is the exception. It lays out the environment in which these developments are occurring. Why are so many people, so many organisations devoting resources to preventing counterfeits? The answer is obviously because criminals are producing counterfeits and they should be prevented from doing so.So the first part of this paper surveys the situation pertaining in the world of counterfeits. This may not be new information to some of you, but others may be surprised -perhaps alarmed -at the view presented. The second part of this paper examines the need to improve communication between those producing and developing counterfeit detenence devices and those that should be using them. Through better communication, deterring counterfeits can be more successfully achieved. THE IMPACT OF COUNTERFEITING CRIME.There are several adverse affects of counterfeiting:1. Economic costs, a direct result of counte...