Spiny-headed worms – Acanthocephala – are a rather small group of organisms (approx. 1300 species are known to date) which all have a parasitic lifestyle. As larvae (cystacanths) they are found within the haemocoel of arthropods, mainly insects and crustaceans. Adult acanthocephalans are found in every class of vertebrates with fish being a preferred group of definitive hosts. After copulation, female worms release embryonated eggs into the intestine of the vertebrate. The eggs that already contain the first larval stage called acanthor, are released with the faeces of the host into the environment. After ingestion by suitable intermediate hosts, the acanthor hatches inside the intestine of the intermediate host, passes through the intestinal wall and develops into the infective cystacanth stage in the haemocoel of the arthropod. As this group of parasites lacks medical importance (only a few species are accidentally found in humans) there is only a small number of researchers studying these organisms. It is therefore very much appreciated to have a new book dealing with these fascinating organisms 20 years after the publication of Biology of the Acanthocephala.

The focus of this book is to understand the life and success of acanthocephalans from the ecological point of view. This is one of the most important issues for the author Clive R. Kennedy, a renowned ecological parasitologist who studied acanthocephalans for most of his scientific career. The author has encouraged many other researchers (like myself) to see host-parasite interactions from an ecological point of view. He summarized his philosophy very clearly in a plenary talk during a meeting of the Scandinavian Society for Parasitology, 1995 in Jyväskylä, Finland when he said “Biodiversity decline is a major global crisis since it is irreversible. Biodiversity still tends to be equated with free-living organisms, especially mammals, birds and plants but parasites are ignored. Parasites may represent 50 % of all living organisms and we should be just as concerned about the decline in their biodiversity and their extinction: there is no moral or ethical right to except them.”

According to this key understanding of biodiversity and ecology it is the objective of the present book to show that parasitology is an ecological discipline as it is concerned with the relationships between 2 species: the host and the parasite. Furthermore, due to their ecological importance in food webs, acanthocephalan (and parasite) diversity is an integral part of biodiversity. Based on this understanding of parasitology and the life of acanthocephalans in particular, the book is divided into 10 chapters.

During the introduction the main intentions of the book are presented combined with the basic characteristics of acanthocephalans and the necessity to use an ecological attempt in order to explain the distribution and abundance of acanthocephalans. The following chapter – ‘Life cycle and transmission’ – gives a comprehensive overview of the morphology of all developmental stages and summarizes all details about acanthocephalan life-cycles. As general features concerning ‘Biogeography and distribution’ it is pointed out that acanthocephalans are primarily an aquatic group of parasites, being mainly found in fish and birds whereas reptiles and amphibians are less frequently infected. As a further general rule it appears that only omnivorous, piscivorous or carnivorous species are likely to be regularly infected with these worms. The next 2 chapters – ‘Specificity’ and ‘Host parasite interactions’ – discuss intermediate and final host specificity as well as distribution and manipulation patterns. ‘Dynamics of populations’ and ‘Communities’ are the topics of the subsequent chapters which show that the role of acanthocephalans in the composition, richness and structuring of helminth communities in freshwater fish is variable in place and time and is seldom, if ever predictable. In the chapter ‘Introductions and extinctions’ remarkable examples of successful invasions and local extinctions were presented although no example is known where an acanthocephalan species got extinct on a worldwide basis. The ‘Relations’ of acanthocephalans to ‘Ecosystem changes’ are described in chapter 9 with a focus on acanthocephalans as biological tags and as indicators of pollution. The last chapter contains the ‘Conclusions and overview’ in which Clive Kennedy gave a precise summary of the ecology of acanthocephalans. It is pointed out that it is crucial to study the ecology of acanthocephalans rather than their phylogeny in order to understand their patterns of survival and success.

All chapters are well referenced with a bibliography of 30 pages and nearly 550 references. The book is an up-to-date review about acanthocephala for which I can only congratulate the author. I hope this book will be read by many students and researchers as it will surely encourage them to see acanthocephalans as fascinating organisms and as important players in ecosystems.