Preface

Chapter 6 **Spatiotemporal Neural Activities Involved in the Olfactory**

Chapter 7 **Lipid Composition Modifications in the Blue Mussels (Mytilus**

Chapter 8 **An Insightful Model to Study Innate Immunity and Stress**

Chapter 9 **Gut Microbiome Analysis of Snails: A Biotechnological**

**edulis L.) from the White Sea 143**

**Bathymodiolus azoricus 161**

**Technique 119** Minoru Saito

**VI** Contents

Santos

**Approach 189**

Bhattacharya

Chapter 10 **The Uniqueness of Achatina fulica in its Evolutionary Success 219**

**Processing of the Land Slug using Fluorescent-Imaging**

Natalia N. Fokina, Tatiana R. Ruokolainen and Nina N. Nemova

**Response in Deep‐Sea Vent Animals: Profiling the Mussel**

Raul Bettencourt, Inês Barros, Eva Martins, Inês Martins, Teresa Cerqueira, Ana Colaço, Valentina Costa, Domitília Rosa, Hugo Froufe, Conceição Egas, Sergio Stefanni, Paul Dando and Ricardo S.

Mudasir A. Dar, Kiran D. Pawar and Radhakrishna S. Pandit

Sandip Mukherjee, Shuvasree Sarkar, Chayan Munshi and Shelley

Malacology, the study of molluscs, is an age-old discipline of natural science. Its genesis perhaps dates back to the time of Aristotle. Mollusc is the second largest group of invertebrates after arthropods. The group is represented by snails, oysters, squids, octopuses, slugs, clams and their relatives. Scientists had recorded nearly 200,000 extant species of molluscs on earth occu‐ pying diverse ecological niches. They also exhibit a significant paleontological evidence since Cambrian. Molluscs present a wide range of variation with reference to their anatomy, physiol‐ ogy, behaviour, adaptation, food preference and habitat selection. Body plan of mollusc is ex‐ tremely varied, which ranges from tiny worm–like creatures to giant squids, a relatively less researched group of cephalopod. Molluscs bear several taxonomical classes of organisms with distinct morphofunctional attributes. They are distributed widely in all zoogeographical realms. An advanced level of adaptational efficiency and physiological resilience enabled molluscs to survive and propagate in diverse ecological conditions over the span of millions of years of evolution. Ecologically, they are distributed in almost all types of environments, namely, aquat‐ ic, terrestrial and deep sea regions. Their existence from hydrothermal vent was indicative to their adaptational uniqueness, which enabled them to survive in an extreme environmental con‐ dition with a minimal level of interspecific competition.

Molluscs, in general, evolved an advanced mode of innate immune system, which, with other factors, might have played a key role in their evolutionary success. Report of efficient phago‐ cytes, cytotoxic molecules, agglutinins and possible Toll-like receptors is the evidence of effec‐ tive immunoresponsiveness against pathogen and toxin characteristic to this group. Similarity of immunological system between mollusc and mammal is also claimed. Aquatic molluscs, in recent years, have been identified as effective monitoring organisms of the water quality of lotic and lentic ecosystems. Filter feeding mode of digestion enabled them to interact with diverse groups of environmental contaminants and pathogens intimately. Malacologists had identified several cellular, molecular and biochemical markers of ecotoxicity both in the gastropods and bivalve species. Cellular apoptosis, respiratory burst activity, lysosomal membrane fragility and lysozyme activity in the immunocytes of molluscs had already been suggested as effective bio‐ markers of toxicity. Gene expression analysis under pathogen and toxin exposure is compara‐ tively a new area of malacological research. Being a putative source of ethnomedicines and bioactive molecules, several species of molluscs bear a high degree of biotechnological and pharmaceutical significance. However, molluscan biodiversity and its rational utilisation is a less researched area with limited scientific information.

Molluscs, in general, bear an immense degree of societal and other influences on mankind. It is an established source of food and ethnomedicine for human, culturable fish and poultry. It is a lucrative source of ornamental shell and pearl and thus bears a special commercial importance. In recent years, malacology has been gaining a special scientific significance due to novel dis‐ coveries and findings in the areas of physiology, biochemistry, molecular biology and ethology. Development of advanced instrumentation technology enabled the malacologists to gather a new set of information on basic and applied malacology. For the last 20 years, horizon of mala‐ cological research has been expanding by leaps and bound globally. The World Congress of Malacology held at Washington DC in 1998 is a major landmark initiative towards consolidation and exchange of ideas among the fellow researchers. In this book, the authors made significant contribution by addressing the frontier areas of organismal, molecular and biochemical mala‐ cology. Multiple chapters with current malacological information were collated in two separate sections. Contribution of the scientists from diverse research interests would make this edited volume a well-informative one for the concerned researchers, teachers and students.

In current years, organismal and molecular aspects of research have been identified as the two broad attributes of malacological investigation adopted in different laboratories. A paradigm shift that occurred in the trend of malacological research during the last two decades has well been reflected in these two sections. In the 'Organismal Malacology' section, a review was pre‐ sented on the bioecology and aquaculture of pen shell, an economically important mollusc of the Gulf of California, Mexico. Issues related to the taxonomical problem of Conoidea had been dealt in this section with appropriate citations and research evidence. Mussels are considered as sentinel species in ecotoxicology. Functional significance of mussel as a tool to monitor the wa‐ tershed quality was presented following the biomarker approach. An overview on the biology and conservation of patellid limpets, a keystone species of rocky shore, highlighted the impor‐ tance of biological traits on effective management of this group in their natural habitat. In anoth‐ er chapter of this section, the author discussed the morphological characteristics of a gastropod *Babylonia spirata* of Tuticorin coast of India from taxonomical point of view. In the other section, entitled 'Cellular and Molecular Malacology', current trends of biochemical and molecular mal‐ acological research were highlighted in several chapters. Arsenic and sulphates are the chemical contaminants linked to coal mining and related processing. Differential patterns of gene expres‐ sion of mussel were characterised under the exposure of these toxins in controlled conditions. The prime objective of the study presented in this chapter is to assess the efficacy of gene tran‐ scriptional markers in monitoring the degree of contamination. In another chapter, the author reported an elaborative study of spatiotemporal neural activity during olfactory processing in a land slug using state-of-the-art technology of imaging. Bacterial symbionts of molluscan gut bear industrial prospect and are a less explored area of research. Authors addressed an impor‐ tant area of applied malacology concerning the functional spectrum of heterogeneous bacterial groups inhabiting the gastrointestinal niches. Highly advanced innate immune system is a char‐ acteristic evolutionary trend as recorded in mollusc. This section included a chapter on molecu‐ lar immunological adaptation of molluscs of deep sea hydrothermal vent—a less studied ecosystem of earth. In another review, authors documented their holistic view on the biochemi‐ cal adaptation of lipid composition in marine bivalve in the face of various ecological factors. Evolutionary success of *Achatina fulica* was discussed with references to its innate immunologi‐ cal status and prospect as a source of ethnomedicine and other bioactive molecules. Molecular biology and biochemistry of C-reactive protein, glycosaminoglycan and immunoregulatory re‐ sponses were explained on the basis of available scientific information.

At last, I remain thankful to Ms. Ana Pantar and Ms. Mirena Calmic of InTech for their earnest cooperation and help that I received in every step of editing of this book. My thanks go to my wife and research colleague Dr. Mitali Ray and my doctoral students of my laboratory of Aquat‐ ic Toxicology for providing me with appropriate academic inputs and technical assistance dur‐ ing this exercise.

> **Sajal Ray** Professor of Zoology University of Calcutta, India
