Lyngbya
Lyngbya is a genus of cyanobacteria, unicellular autotrophs that form the basis of the oceanic food chain. As a result of recent genetic analyses, several new genera were erected from this genus: "e.g.", "Moorea", "Limnoraphis", "Okeania", "Microseira", and "Dapis". "Lyngbya" species form long, unbranching filaments inside a rigid mucilaginous sheath. Sheaths may form tangles or mats, intermixed with other phytoplankton species. They reproduce asexually. Their filaments break apart and each cell forms a new filament. The mats grow around atolls, salt marshes, or fresh water. Some "Lyngbya" species cause the human skin irritation called seaweed dermatitis. Some "Lyngbya" species  can also temporarily monopolize aquatic ecosystems when they form dense, floating mats in the water. Ingestion of "Lyngbya" is potentially lethal. Most commonly, poisoning is caused by eating fish which have fed on "Lyngbya" or which have fed on other fish which have consumed "Lyngbya". This is called "ciguatera-like" poisoning.