Recent progress in the structural elucidation, instrumental analyses and evaluation of the toxicological effects of dinoflagellate and related toxins was reviewed: eight polyether toxins were isolated from shellfishes involved in diarrhetic shellfish poisoning (seven with determined structures, categorized into carboxylic acid toxins like okadaic acid and dinophysistoxins, neutral lactones like pectenotoxins, and a sulfated toxin yessotoxin), with okadaic acid and dinophysistoxins detected in Dinophysis acuminata, D. fortii and Prorocentrum lima (the latter producing many okadaic acid derivatives); matotoxin, a bissulfate polyether toxin more lethal than palytoxin, was isolated from Gambierdiscus toxicus; two ichthyotoxic and hemolytic monoacylgalactosylglycerolipids were isolated from Amphidinium carteri; highly sensitive fluorometric HPLC methods for diarrheal and paralytic shellfish toxins were developed; toxicological studies emphasized the need to focus on chronic effects on human health. The biogenetic origin of tetrodotoxin and its derivatives was explored via food chain and symbiotic bacteria tests: tetrodotoxin analogs were found in parrotfishes, an angelfish, xanthid crabs, their diet alga, and an annelid (marked toxin content fluctuation implying exogenous origin); tetrodotoxin and anhydrotetrodotoxin were unambiguously confirmed in the culture broth of Alteromonas sp. from an alga and a crab, and in bacteria from pufferfishes' skin and intestine, identifying bacteria as the biogenetic source, with toxin-containing animals (including pufferfishes) presumed to accumulate toxin through the food chain or infection. Preliminary investigations on hydrolytic enzymes in stonefish (Family Synanciidae) venom sac extracts showed: venom was extracted by homogenizing intact venom sacs in cold phospho-buffered saline (pH 7.4) and centrifuging; proteinase activity was assayed using four synthetic chromogenic substrates (optimum pH 8.5-9.0, specific activities 17.4-1048.5 mU/mg, suggesting presence of thrombin, plasma kallikrein, urokinase, plasmin, trypsin, and glandular kallikrein-like enzymes); phosphodiesterase activity was detected with thymidine 5'-monophosphate p-nitrophenyl ester (no activity with the 3'-substrate, indicating specificity for hydrolyzing 5'-phosphate ester bonds).