Marine Chemical Ecology

Marine Chemical Ecology

Marine Science Series The CRC Marine Science Series is dedicated to providing state-of-theart coverage of important topics in marine biology, marine chemistry, marine geology, and physical oceanography. The series includes volumes that focus on the synthesis of recent advances in marine science.

CRC MARINE SCIENCE SERIES SERIES EDITOR Michael J. Kennish, Ph.D. PUBLISHED TITLES Artificial Reef Evaluation with Application to Natural Marine Habitats, William Seaman, Jr. Chemical Oceanography, Second Edition, Frank J. Millero Coastal Ecosystem Processes, Daniel M. Alongi Ecology of Estuaries: Anthropogenic Effects, Michael J. Kennish Ecology of Marine Bivalves: An Ecosystem Approach, Richard F. Dame Ecology of Marine Invertebrate Larvae, Larry McEdward Ecology of Seashores, George A. Knox Environmental Oceanography, Second Edition, Tom Beer Estuary Restoration and Maintenance: The National Estuary Program, Michael J. Kennish Eutrophication Processes in Coastal Systems: Origin and Succession of Plankton Blooms and Effects on Secondary Production in Gulf Coast Estuaries, Robert J. Livingston Handbook of Marine Mineral Deposits, David S. Cronan Handbook for Restoring Tidal Wetlands, Joy B. Zedler Intertidal Deposits: River Mouths, Tidal Flats, and Coastal Lagoons, Doeke Eisma Morphodynamics of Inner Continental Shelves, L. Donelson Wright Ocean Pollution: Effects on Living Resources and Humans, Carl J. Sindermann Physical Oceanographic Processes of the Great Barrier Reef, Eric Wolanski The Physiology of Fishes, Second Edition, David H. Evans Pollution Impacts on Marine Biotic Communities, Michael J. Kennish Practical Handbook of Estuarine and Marine Pollution, Michael J. Kennish Seagrasses: Monitoring, Ecology, Physiology, and Management, Stephen A. Bortone

Marine Chemical Ecology Edited by

James B. McClintock Professor of Biology University of Alabama at Birmingham Birmingham, Alabama

Bill J. Baker Associate Professor of Chemistry University of South Florida Tampa, Florida

CRC Press Boca Raton London New York Washington, D.C.

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Cover photograph © 1997 Norbert Wu/www.norbertwu.com. The antarctic red macroalga, Phyllophora antarctica, being held by the sea urchin, Sterchinus neumayeri, in a mutualistic relationship mediated by chemical and physical defenses. See Amsler, C.D., McClintock, J.B., and Baker, B.J., Mar. Ecol. Prog. Ser., 1999, 183, 105, and Chapter 7 in this volume.

Library of Congress Cataloging-in-Publication Data Marine chemical ecology / James B. McClintock, Bill J. Baker, editors. p. cm.—(Marine science series) Includes bibliographical references and index. ISBN 0-8493-9064-8 (alk. paper) 1. Marine chemical ecology. I. McClintock, James B. II. Baker, Bill J. (Bill James), 1958- III. Series. QH541.5.S3 M254 2001 577.7′14—dc21

2001025040

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Preface As early as the middle of the 19th century, scientists were beginning to isolate and characterize organic compounds from nature. Modern studies of the nature of natural products, those compounds not involved in primary metabolic processes, began in the 1930s and 1940s. In the decades that followed, scientists began to focus on why organisms produce these compounds. At the same time, studies of factors that regulate the distribution and abundance of species were giving rise to the field of ecology. The subsequent combination of these two disciplines allowed for investigations of secondary metabolites and their functional roles in mediating reproductive processes, predator–prey interactions, and competition. The inherently interdisciplinary field of chemical ecology has as its roots studies of chemical interactions in terrestrial microbial and plant systems. Terrestrial plant studies led to the logical extension of similar studies in marine plants, primarily macroalgae. The earliest studies of the chemical ecology of marine animals focused on invertebrates that were plant-like, lacking locomotive ability or obvious physical means of protection. Surprisingly, such marine studies really only have been undertaken in earnest during the past 25 years, due largely to the lack of knowledge of the chemistry of marine organisms. It is probably no coincidence that the breadth of marine organisms studied expanded in concert with developments in underwater technology. Today, the field of marine chemical ecology encompasses a broad interdisciplinary community of scientists. Among its many participants are those interested in understanding predator–prey interactions, competition, chemical communication, fouling, pathogen–host interactions, biosynthesis, reproduction, and the evolution of secondary metabolites. Bringing diverse disciplines to bear upon these fundamental questions has generated a body of knowledge that is truly synergistic and unequivocally greater than the sum of its parts. The field of marine chemical ecology has been gaining momentum. Over the past decade, a number of excellent review articles and at least one book have been published on this topic. However, a field so diverse and interdisciplinary requires, from time to time, a conceptual synthesis. There has been, to date, no single source that provides this synthetic overview. This book is such an attempt. In four topical sections, this work spans aspects of marine chemical ecology from molecular to community levels, bridging these diverse disciplines. The authors have contributed their considerable experiences, resulting in a collective effort that will hopefully stimulate new ideas and inspire a new generation of researchers. The introductory section, Chapters 1 through 3, provides a broad phylogenetic overview of marine organic chemistry. Emphasizing evolutionary, ecological, and biosynthetic considerations, the authors of these chapters set a foundation for the chapters that follow. Harper et al. provide the first balanced account of patterns of specific classes of secondary metabolites among marine organisms. Garson has provided an update of her periodic reviews of the field of marine biosynthesis with an emphasis on ecologically important compounds. Cimino and Ghiselin foray into theoretical analyses of evolutionary trends in marine biota in an effort to rationalize observed patterns of chemical defense in the marine realm. The second section, Chapters 4 through 10, takes an organismal approach to understanding the role of secondary metabolites in mediating trophic interrelationships. While much of the content of this volume focuses on sessile organisms, Stachowicz reports on chemical ecology of mobile benthic invertebrates, and McClintock et al. review what is known to date about the chemical ecology of meroplankton and holoplankton and offer suggestions for future research. Trophic relationships in the oceanic water column have potential significance in influencing material and

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energy flux in planktonic food webs. Chemical ecology is ultimately driven by evolutionary pressures, which Cronin reviews from the point of view of resource allocation strategies. The macroalgae are perhaps most thoroughly studied with respect to their trophic chemical ecology. This fertile field is addressed by Paul et al. Marine chemical ecology has also been considered on broad biogeographic and temporal scales. Most notable among marine biogeographic analyses are those applied to the macroalgae, the resulting patterns of which are reviewed by Van Alstyne et al. Biogeographic patterns in higher organisms are less well defined; however, recent evidence from the south polar region, which Amsler et al. review from a chemical analytical perspective, is beginning to illuminate global patterns, at least with respect to trophic interactions. Furthering our understanding of the functional spatial distribution of metabolites, Steinberg et al. examines chemical interactions at organismal surfaces. Section III, Chapters 11 through 15, reviews cellular and physiological aspects of marine chemical ecology. Targett and Arnold address the physiological consequences of ingesting secondary metabolites. Amsler and Iken review behavioral mechanisms by which algae and bacteria use and exploit chemical gradients. The important role of chemical cues in determining patterns of settlement and metamorphosis in many marine plants and invertebrates are well known. Hadfield and Paul take a comprehensive approach reviewing recent efforts to understand the chemical nature of settlement and metamorphic cues. Trapido-Rosenthal details the role of natural products in prey attraction and other aspects of chemoreception. Completing this section, Karentz sheds light on the important role of UV-absorbing compounds in defending marine organisms from damage due to harmful solar radiation. Last, but by no means least, Chapters 16 through 18 review modern studies of marine chemical ecology, which, in effect if not in purpose, may lead to practical applications. Secondary metabolites long studied for the sake of knowledge have become commodities to the pharmaceutical industry; the means by which chemical ecological cues can be exploited for purposes of drug discovery are reviewed by Sennett in Chapter 16. Similarly, Rittschof takes a view of secondary metabolites which deter settlement as applied to the discovery of compounds which can be applied to marine surfaces to deter fouling, a major impediment to smooth sailing. Bernan reviews a relatively new area of research which focuses on the secondary metabolism of marine prokaryotic microbes. The success of drugs, agrochemicals, antifouling agents, and/or similar marine natural products in the marketplace will ultimately benefit the entire field due to increased public interest and heightened awareness of the resources available from the marine realm. As we sit in our office here at Palmer Station, Antarctica, pursuing our own chemical ecological interests, our job of editing and organizing the contributed chapters is just beginning. We are especially grateful to the contributors to this volume who have taken considerable time from their busy schedules to produce, in every case, informative, well-written, and timely monographs; their dedication and thoroughness have made our jobs easy. Equally so, the efforts of the many reviewers of the individual chapters are gratefully acknowledged. The end result is now clear. The sum of this collection of topics creates a high-resolution snapshot of marine chemical ecology as we understand it at the beginning of the 21st century. We hope that readers will find much information within this book to interest them, some information to provoke them, and ultimately, at least one thing they are compelled to further investigate. Thus, the stage will be set for future developments in the field. We are also indebted to the Office of Polar Programs and Division of Ocean Sciences at the National Science Foundation for their continued support which has, in part, made this book possible. J.B.M. would like to dedicate his input into this book to Ferne, Luke, and Jamie in acknowledgment of their patience and support. B.J.B. wishes to dedicate his contribution to Jill and Jeremy, whose enthusiastic interest and encouragement are a constant inspiration. James B. McClintock Bill J. Baker

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Editors James B. McClintock, Ph.D., is a professor in the Department of Biology and dean of the School of Natural Sciences and Mathematics at the University of Alabama at Birmingham. He received his B.S. degree from the University of California at Santa Cruz in 1978. Working in the laboratory of Dr. John Lawrence, he earned his M.S. and Ph.D. degrees from the University of South Florida in 1980 and 1984, respectively. He was a National Science Foundation (NSF) postdoctoral fellow in the laboratory of Dr. John Pearse at the University of California at Santa Cruz from 1984 to 1987. Dr. McClintock was appointed assistant professor of biology in the Department of Biology at the University of Alabama at Birmingham in 1987, and became an associate professor and then professor of biology in 1993 and 1997, respectively. In 1999 he was named dean of the School of Natural Sciences and Mathematics at the University of Alabama at Birmingham. Dr. McClintock has taught invertebrate zoology in the Department of Biology at the University of Alabama at Birmingham. For the past 8 years he has also taught field courses in Tropical Ecology at the Bahamian Field Station and Tropical Rainforest Ecology in Tortuguero National Park in Costa Rica. Dr. McClintock has been the recipient of numerous grants from NSF and the National Oceanographic and Atmospheric Association (NOAA). He is a member of the Society for Integrative and Comparative Biology, the honorary society of Sigma Xi, and was elected a fellow of the American Association for the Advancement of Science in 1999. He has published over 150 papers and presented numerous invited lectures. His research interests are marine invertebrate chemical ecology, nutrition, reproduction, and evolution. He enjoys nature photography, hiking and camping, racquetball, and bluegrass and classical music. Bill J. Baker, Ph.D., is associate professor of chemistry at the University of South Florida. He studied chemistry as an undergraduate at California Polytechnic State University, San Luis Obispo, receiving his B.S. degree in 1982. He studied bioorganic chemistry at the University of Hawaii at Manoa, under Paul J. Scheuer, earning his Ph.D. degree in 1986. After postdoctoral training in biosynthesis with Ron Parry at Rice University and Carl Djerassi at Stanford University, he was appointed assistant professor of chemistry at Florida Institute of Technology in 1990 where he advanced through the academic ranks before accepting his current position at the University of South Florida in 2001. Dr. Baker has engaged in teaching and research in organic chemistry. He stays young by teaching sophomore organic chemistry and he stays current in his field by teaching graduate courses in the chemistry of natural products and in organic structure determination. He has published widely in the areas of marine natural products isolation, characterization, bioactivity, marine chemical ecology, synthesis and biosynthesis of marine metabolites, and marine biotechnology. His research has taken him to the underwater worlds of the warm South Pacific and Caribbean and to the cold polar waters of Antarctica, where he always finds the interface of field biology and organic chemistry fascinating. His research has been supported by a variety of sources, including the NSF, the National Institutes of Health, the NOAA, as well as private and commercial collaborators interested in potential uses of these products. Dr. Baker has been active in the American Society of Pharmacognosy and is a member of the American Chemical Society, the American Association for the Advancement of Science, the International Society of Chemical Ecology, and Sigma Xi. He has served extensively as peer reviewer for granting agencies and journals and on advisory panels for several government agencies. He

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enjoys outdoor activities with his family, including camping, bicycling, and hiking, and he is an avid runner. On July 21, 1998 the United States Board on Geographic Names recognized Drs. McClintock and Baker by naming geographic features after them on the north (McClintock Point) and south (Baker Point) sides of Explorers Cove, New Harbor, McMurdo Sound, Antarctica. This honor was bestowed upon them to recognize their extensive contributions to Antarctic marine biology and chemical ecology.

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Contributors Charles D. Amsler Department of Biology University of Alabama at Birmingham Birmingham, Alabama Thomas M. Arnold Pesticide Research Laboratory Pennsylvania State University University Park, Pennsylvania Bill J. Baker Department of Chemistry University of South Florida Tampa, Florida Valerie S. Bernan Natural Products Microbiology Research Wyeth-Ayerst Research Pearl River, New York Tim S. Bugni Department of Medicinal Chemistry University of Utah Salt Lake City, Utah

Rocky de Nys Schools of Biological Science and Microbiology and Immunology University of New South Wales Sydney, Australia Megan N. Dethier Friday Harbor Laboratories University of Washington Friday Harbor, Washington David O. Duggins Friday Harbor Laboratories University of Washington Friday Harbor, Washington Mary J. Garson Department of Chemistry University of Queensland Brisbane, Australia Michael T. Ghiselin Department of Invertebrate Zoology California Academy of Sciences San Francisco, California

Guido Cimino Istituto per la Chimica di Molecole di Interesse Biologico Napoli, Italy

Michael G. Hadfield Department of Zoology University of Hawaii at Manoa Honolulu, Hawaii

Brent R. Copp Department of Chemistry University of Auckland Auckland, New Zealand

Mary Kay Harper Department of Medicinal Chemistry University of Utah Salt Lake City, Utah

Greg Cronin Department of Biology University of Colorado at Denver Denver, Colorado

Katrin B. Iken Department of Biology University of Alabama at Birmingham Birmingham, Alabama

Edwin Cruz-Rivera Marine Laboratory University of Guam Mangilao, Guam

Chris M. Ireland Department of Medicinal Chemistry University of Utah Salt Lake City, Utah

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Robyn D. James Department of Medicinal Chemistry University of Utah Salt Lake City, Utah

John J. Stachowicz Section of Evolution and Ecology University of California Davis, California

Deneb Karentz Department of Biology University of San Francisco San Francisco, California

Deborah K. Steinberg Bermuda Biological Station for Research, Inc. Ferry Reach, Bermuda

Staffan Kjelleberg School of Microbiology and Immunology University of New South Wales Sydney, Australia Brent S. Lindsay Department of Medicinal Chemistry University of Utah Salt Lake City, Utah James B. McClintock Department of Biology University of Alabama at Birmingham Birmingham, Alabama Valerie J. Paul Marine Laboratory University of Guam Mangilao, Guam Adam D. Richardson Department of Medicinal Chemistry University of Utah Salt Lake City, Utah Dan Rittschof Marine Laboratory Duke University Beaufort, North Carolina Peter C. Schnabel Department of Medicinal Chemistry University of Utah Salt Lake City, Utah Susan H. Sennett Division of Biomedical Marine Research Harbor Branch Oceanographic Institution, Inc. Fort Pierce, Florida

Peter D. Steinberg School of Biological Science University of New South Wales Sydney, Australia Nancy M. Targett Graduate College of Marine Studies University of Delaware Lewes, Delaware Deniz Tasdemir Department of Medicinal Chemistry University of Utah Salt Lake City, Utah Robert W. Thacker Marine Laboratory University of Guam Mangilao, Guam and presently at Department of Biology University of Alabama at Birmingham Birmingham, Alabama Henry G. Trapido-Rosenthal Bermuda Biological Station for Research, Inc. Ferry Reach, Bermuda Kathryn L. Van Alstyne Shannon Point Marine Center Western Washington University Anacortes, Washington Ryan M. VanWagoner Department of Medicinal Chemistry University of Utah Salt Lake City, Utah Sheryl M. Verbitski Department of Medicinal Chemistry University of Utah Salt Lake City, Utah

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Table of Contents Section I Background ........................................................................................................................................1 Chapter 1 Introduction to the Chemical Ecology of Marine Natural Products.................................................3 Mary Kay Harper, Tim S. Bugni, Brent R. Copp, Robyn D. James, Brent S. Lindsay, Adam D. Richardson, Peter C. Schnabel, Deniz Tasdemir, Ryan M. VanWagoner, Sheryl M. Verbitski, and Chris M. Ireland Chapter 2 Ecological Perspectives on Marine Natural Product Biosynthesis .................................................71 Mary J. Garson Chapter 3 Marine Natural Products Chemistry as an Evolutionary Narrative ..............................................115 Guido Cimino and Michael T. Ghiselin Section II Organismal Patterns in Marine Chemical Ecology .......................................................................155 Chapter 4 Chemical Ecology of Mobile Benthic Invertebrates: Predators and Prey, Allies and Competitors..................................................................................157 John J. Stachowicz Chapter 5 The Chemical Ecology of Invertebrate Meroplankton and Holoplankton ...................................195 James B. McClintock, Bill J. Baker, and Deborah K. Steinberg Chapter 6 Chemical Mediation of Macroalgal–Herbivore Interactions: Ecological and Evolutionary Perspectives.....................................................................................227 Valerie J. Paul, Edwin Cruz-Rivera, and Robert W. Thacker Chapter 7 Secondary Metabolites from Antarctic Marine Organisms and Their Ecological Implications......267 Charles D. Amsler, Katrin B. Iken, James B. McClintock, and Bill J. Baker Chapter 8 Spatial Patterns in Macroalgal Chemical Defenses ......................................................................301 Kathryn L. Van Alstyne, Megan N. Dethier, and David O. Duggins

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Chapter 9 Resource Allocation in Seaweeds and Marine Invertebrates: Chemical Defense Patterns in Relation to Defense Theories .......................................................325 Greg Cronin Chapter 10 Chemical Mediation of Surface Colonization ...............................................................................355 Peter D. Steinberg, Rocky de Nys, and Staffan Kjelleberg Section III Cellular and Physiological Patterns in Marine Chemical Ecology...............................................389 Chapter 11 Effects of Secondary Metabolites on Digestion in Marine Herbivores........................................391 Nancy M. Targett and Thomas M. Arnold Chapter 12 Chemokinesis and Chemotaxis in Marine Bacteria and Algae.....................................................413 Charles D. Amsler and Katrin B. Iken Chapter 13 Natural Chemical Cues for Settlement and Metamorphosis of Marine-Invertebrate Larvae.......431 Michael G. Hadfield and Valerie J. Paul Chapter 14 Contributions of Marine Chemical Ecology to Chemosensory Neurobiology.............................463 Henry G. Trapido-Rosenthal Chapter 15 Chemical Defenses of Marine Organisms Against Solar Radiation Exposure: UV-Absorbing Mycosporine-Like Amino Acids and Scytonemin................................................481 Deneb Karentz Section IV Applied Marine Chemical Ecology ...............................................................................................521 Chapter 16 Marine Chemical Ecology: Applications in Marine Biomedical Prospecting..............................523 Susan H. Sennett Chapter 17 Natural Product Antifoulants and Coatings Development ............................................................543 Dan Rittschof Chapter 18 Metabolites of Free-Living, Commensal, and Symbiotic Benthic Marine Microorganisms .......567 Valerie S. Bernan Index ..............................................................................................................................................593

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Section I Background

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1

Introduction to the Chemical Ecology of Marine Natural Products Mary Kay Harper, Tim S. Bugni, Brent R. Copp, Robyn D. James, Brent S. Lindsay, Adam D. Richardson, Peter C. Schnabel, Deniz Tasdemir, Ryan M. VanWagoner, Sheryl M. Verbitski, and Chris M. Ireland*

CONTENTS I. Introduction ............................................................................................................................3 II. Algae ......................................................................................................................................8 III. Porifera .................................................................................................................................10 IV. Cnidaria ................................................................................................................................14 V. Mollusca ...............................................................................................................................17 VI. Echinodermata......................................................................................................................19 VII. Ectoprocta.............................................................................................................................20 VIII. Urochordata ..........................................................................................................................21 IX. Concluding Remarks............................................................................................................23 References ........................................................................................................................................23 Appendix A: Phylogenetic Distribution of Secondary Metabolites (Tables 1.3–1.11) ..................29

I. INTRODUCTION Chemistry is the foundation of all life. Living organisms utilize chemistry for multiple purposes. Obvious examples include lipids utilizing chemistry for cell structure, DNA utilizing chemistry for genetic expression, and proteins utilizing chemistry for cell function and communication. The processes of chemical synthesis and degradation in living systems are termed metabolism, and, invariably, these processes are under enzymatic control. A well-defined set of biosynthetic pathways (see Table 1.1) is used by all organisms for the production of chemicals that are essential for the well-being and survival of the organism. Such chemicals are collectively known as primary metabolites and include lipids, DNA, and proteins. For many years now, chemists have isolated and characterized a diverse range of natural products from both terrestrial and marine organisms. The reason for the presence of such compounds in the organisms was not immediately apparent. It was obvious, however, that these compounds did not resemble the more classical primary metabolites, and they were therefore termed secondary metabolites or natural products. It is becoming increasingly apparent that this terminology is deceptive. Important functions, including ecological roles,

* Corresponding author. 0-8493-9064-8/01/$0.00+$1.50 © 2001 by CRC Press LLC

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are being attributed to secondary metabolites. Indeed, natural products may contribute as much as primary metabolites to the survival of the producing organism. Theories abound as to why secondary metabolites are produced by marine organisms. Early theories suggested that such natural products represented chemical “ballast,” waste or products of primary metabolic overflow. However, increasing evidence that many marine natural products play fundamental roles in ecology suggests a more premeditated scenario. In an authoritative account of the theories pertaining to secondary metabolite production, Williams et al. concluded “natural products have evolved under the pressure of natural selection to bind to specific receptors,” and therefore represent ecological responses of organisms to their environment.1 Marine organisms are under intense competitive pressure for space, light, and nutrients especially in such populous locations as tropical reefs. Thus, it is not surprising that these organisms have developed a range of defense mechanisms including behavioral (e.g., cryptic, nocturnal), physical (e.g., sclerites, tough external surfaces), and chemical strategies to ensure survival. Reputed ecological roles for marine natural products include anti-predation, mediation of spatial competition, prevention of fouling, facilitation of reproduction, and protection from ultraviolet radiation. Most studies to date have attempted to assess the more easily quantified feeding deterrence effects of purified compounds. The design, interpretation, and ecological relevance of such experiments, however, have recently come under close scrutiny.2 Although difficult to implement, calls for a holistic approach to marine chemical ecology should not be ignored, as marine natural products do not act in isolation from one another or from physical defenses. For example, testing for synergy between chemical and physical defenses has only recently been addressed in any meaningful manner.3–5 In many cases, preliminary ecological studies have failed to demonstrate well-defined roles for natural products.6 This may be interpreted as support for a chemical “baggage” model, but more likely reflects a present lack of understanding of the complexity of chemically mediated inter- and intra-specific interactions in the marine environment. Marine natural products have already proven their value as catalysts for the discovery and investigation of medicinally important biological systems (e.g., ion channels),7 thus it is inevitable that similar developments will occur in marine biology. The factors that will drive such developments will most likely stem from studies in applied marine chemical ecology. For example, the quest for new nontoxic marine anti-fouling coatings will lead to the identification of natural products that could also be used to probe biochemical mechanisms associated with microbial adhesion, larval settlement, and the induction of metamorphosis. A recent example of such work is the report that furanone natural products interfere with the acylated homoserine lactone (AHL) signaling system in Gram-negative bacteria, a system which is implicated in bacteria bioluminescence, motility, and exoenzyme synthesis.8 Chemists typically classify secondary metabolites according to the metabolic pathways from which they were derived, also called their biosynthesis. The natural products presented in this chapter were classified according to their probable biosynthetic pathway, specifically isoprenoid, acetogenin, shikimate, amino acid, nucleic acid, or carbohydrate.9 Glycosides were classified by the aglycone. Compounds arising from aromatic amino acids were listed as amino acid-derived rather than as shikimates. Compounds that appeared to originate from multiple pathways (i.e., mixed biosynthesis) were classified according to the probable source of the majority of carbons present. Table 1.1 lists representative chemical classes and structures for each biosynthetic pathway. No attempt has been made to second-guess the actual producing organism of secondary metabolites presented in the following sections. For example, natural products isolated from sponges are reported as sponge products, even though in some cases there is evidence that intrinsically associated symbionts are the actual producing organisms. In a similar fashion, metabolites isolated from nudibranchs, which are typically sequestered from dietary sources, are reported as products of the mollusc. This chapter presents macroalgae first, followed by invertebrate phyla listed from the most primitive to the most advanced marine phyla. The seagrasses and several invertebrate phyla, which account for none or a very small number of natural products (