Dinoflagellates are a type of single-celled organism found in marine and freshwater environments. They are known for their unique features, including two flagella that allow them to move through water. Some species can produce light, creating a phenomenon known as bioluminescence. These organisms play a crucial role in aquatic ecosystems as primary producers, forming the base of the food web. However, certain dinoflagellates can also cause harmful algal blooms, which can lead to red tides and negatively impact marine life and human health.