Dinoflagellates are unicellular protists that thrives mainly in oceans and seas. They are photosynthetic and are freely existing in nature. They are important in the food chain since they are source of food and oxygen to other marine animals and plants.
There is a phenomena called the algal bloom where in a specific dinoflagellate populate a specific area of the sea thus discoloration of the sea surface is noticeable. This is termed locally to be as red tide. During red tide, dinoflagellates produces toxins which are neurotoxic to aquatic/marine creatures when ingested.
Humans can be affected by the toxins when they eat any of the fish or shellfish that are contaminated with neurotoxins. These neurotoxins can affect our respiratory tract by affecting first the nerves thus paralyzing it. Respiratory difficulty will now arise because as the nerves are incapacitated, the blood vessels will function abnormally thus decreasing the supply of oxygen throughout the body. Unattended victim may become comatose due to severe lack of oxygen in the brain. This is collectively termed as respiratory paralysis.