Marine Organisms and Natural Products : Why are there poisons and how did they get there? “More than Meets the Mouth”

Why do marine organisms produce secondary metabolites: Many plants and animals, both terrestrial and marine, produce compounds that help them survive by, for example, deterring potential predators, warding off pathogens, keeping their living space free from competitors, and even reducing the impact of exposure to environmental stresses, such as high levels of solar UV radiation. Thus, these chemicals have an enormous impact on the outcome of interactions between species and the structure and function of communities and ecosystems. Many plants and animals, both terrestrial and marine, produce compounds that help them survive by, for example, deterring potential predators, warding off pathogens, keeping their living space free from competitors, and even reducing the impact of exposure to environmental stresses, such as high levels of solar UV radiation. Thus, these chemicals have an enormous impact on the outcome of interactions between species and the structure and function of communities and ecosystems.

Secondary metabolites Many organisms have been found to defend themselves by producing toxins or other small molecules. Many organisms have been found to defend themselves by producing toxins or other small molecules. Also known as natural products. Also known as natural products. Chemicals which posses an unknown functional role. Chemicals which posses an unknown functional role. Generally limited to a specific species or even a chemotypical subset of a species. Generally limited to a specific species or even a chemotypical subset of a species.

Examples of Marine Organisms that produce or harbor natural products: Sponges Sponges Algae Algae Bryozoans Bryozoans Mollusks Mollusks Cnidarians Cnidarians Tunicates Tunicates Echinoderms Echinoderms Sea worms Sea worms Microorganisms Microorganisms

Evolution of chemical defense: Animals that are mobile or that have hard shells or spines are typically not defended by noxious or toxic chemicals.

Sea slugs: Nudibranches, also called sea slugs, typically get their defensive chemistry from the sponges, bryozoans, and sea squirts that they eat. Nudibranches also put defensive compounds in their soft egg ribbons. Many sea slugs have an unusual endosymbiotic association between algal chloroplasts and a marine mollusc, resulting in photosynthetic sea slugs.

Sea weed: Soft fleshy seaweeds found where herbivorous fishes and invertebrates are abundant typically deter predators through the production of distasteful secondary metabolites. Phenolics appear to deter herbivores, but not fish. Most algae produce both polyphenolic and nonpolyphenolic secondary metabolites.

Sponges: An abundant group of coral-reef invertebrates that are very chemically rich. Many sponge chemicals effectively deter potential predators, and many of the distasteful compounds, such as formoside, have now been isolated and structurally characterized. They occasionally develop symbiotic (mutually beneficial) relationship with both algae and bacteria and may contain many complex chemicals that have medicinal value.

Soft coral: Gorgonians, a type of soft coral, lack the hard calcium carbonate skeleton. Their soft texture would seem to make them susceptible to diverse reef predators, but the many novel compounds they produce effectively protect them from predators. Several chemicals have been collected from various types of soft coral: sesquiterpenoids, tetraprenylbenzenoids, diphenylpropane, methylenecholesterols and diterpenoids. Several chemicals have been collected from various types of soft coral: sesquiterpenoids, tetraprenylbenzenoids, diphenylpropane, methylenecholesterols and diterpenoids.

Cnidarians: Hydroids are related to corals and anemones. Stinging organelles called nematocysts protect hydroids that lack a chemical defense. Chemicals, like tridentatol A, defend some hydroids from predators..

Sea squirts: Tunicates, also called sea squirts, are a rich source of secondary metabolites, several of which have been shown to deter feeding by fish, crabs and snails. As chemical defenses, many sea squirts intake and maintain an extremely high concentration of vanadium in the blood, have a very low pH of the tunic due to acid in easily-ruptured bladder cells, and/or produce secondary metabolites harmful to predators and invaders. Some of these metabolites are toxic to cells and are of potential use in pharmaceuticals.

Isopod: Has a thick carpet of blue- green alga growing on it. The alga produces a noxious compound that deters fish from eating the isopod. Because the isopod isn’t eaten by fish, instead of hiding from fish, the isopods live on sun exposed substrates where their symbiont gets plenty of light for photosynthesis. The isopod also eats its symbiont.

References: Charles D. Amsler, James B. McClintock, and Bill J. Baker Secondary Metabolites as Mediators of Trophic Interactions Among Antarctic Marine Organisms Amer. Zool. 41: Charles D. Amsler, James B. McClintock, and Bill J. Baker Secondary Metabolites as Mediators of Trophic Interactions Among Antarctic Marine Organisms Amer. Zool. 41: Kenneth L. Rinehart Secondary Metabolites from Marine Organisms, Ciba Foundation Symposium Secondary Metabolites: their Function and Evolution, (2007) Kenneth L. Rinehart Secondary Metabolites from Marine Organisms, Ciba Foundation Symposium Secondary Metabolites: their Function and Evolution, (2007) Botanica Marina. Volume 51, Issue 3, Pages 161–162, ISSN (Online) , ISSN (Print) , DOI: /BOT , June Botanica Marina. Volume 51, Issue 3, Pages 161–162, ISSN (Online) , ISSN (Print) , DOI: /BOT , June development-marine-sponge-secondary/ development-marine-sponge-secondary/ development-marine-sponge-secondary/ development-marine-sponge-secondary/

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