Marine Toxins: Toxic or poisonous substances elaborated by marine flora or fauna. They include also specific, characterized poisons or toxins for which there is no more specific heading, like those from poisonous FISHES.Oxocins: Compounds based on an 8-membered heterocyclic ring including an oxygen. They can be considered medium ring ethers.Ciguatoxins: Polycyclic ethers produced by Gambierdiscus (DINOFLAGELLATES) from gambiertoxins, which are ingested by fish which in turn may be ingested by humans who are susceptible to the CIGUATERA POISONING.Hydrocarbons, Cyclic: Organic compounds composed exclusively of carbon and hydrogen forming a closed ring that may be either alicyclic or aromatic.Shellfish Poisoning: Poisoning from toxins present in bivalve mollusks that have been ingested. Four distinct types of shellfish poisoning are recognized based on the toxin involved.Cardiidae: A family of bivalve MOLLUSKS with heart-shaped shells, commonly known as cockles. Unlike most BIVALVES, cockles are hermaphroditic.Spiro Compounds: A group of compounds consisting in part of two rings sharing one atom (usually a carbon) in common.Acrylamides: Colorless, odorless crystals that are used extensively in research laboratories for the preparation of polyacrylamide gels for electrophoresis and in organic synthesis, and polymerization. Some of its polymers are used in sewage and wastewater treatment, permanent press fabrics, and as soil conditioning agents.Dinoflagellida: Flagellate EUKARYOTES, found mainly in the oceans. They are characterized by the presence of transverse and longitudinal flagella which propel the organisms in a rotating manner through the water. Dinoflagellida were formerly members of the class Phytomastigophorea under the old five kingdom paradigm.Marine Biology: The study of the origin, structure, development, growth, function, genetics, and reproduction of organisms which inhabit the OCEANS AND SEAS.Cholera Toxin: An ENTEROTOXIN from VIBRIO CHOLERAE. It consists of two major protomers, the heavy (H) or A subunit and the B protomer which consists of 5 light (L) or B subunits. The catalytic A subunit is proteolytically cleaved into fragments A1 and A2. The A1 fragment is a MONO(ADP-RIBOSE) TRANSFERASE. The B protomer binds cholera toxin to intestinal epithelial cells, and facilitates the uptake of the A1 fragment. The A1 catalyzed transfer of ADP-RIBOSE to the alpha subunits of heterotrimeric G PROTEINS activates the production of CYCLIC AMP. Increased levels of cyclic AMP are thought to modulate release of fluid and electrolytes from intestinal crypt cells.Aquatic Organisms: Organisms that live in water.T-2 Toxin: A potent mycotoxin produced in feedstuffs by several species of the genus FUSARIUM. It elicits a severe inflammatory reaction in animals and has teratogenic effects.Oceans and Seas: A great expanse of continuous bodies of salt water which together cover more than 70 percent of the earth's surface. Seas may be partially or entirely enclosed by land, and are smaller than the five oceans (Atlantic, Pacific, Indian, Arctic, and Antarctic).