Perkinsus marinus is a prevalent pathogen of oysters, causing massive mortality in oyster populations. The disease it causes is known as "Dermo", and is characterized by proteolytic degradation of oyster tissues. Due to its negative impact on the oyster industry, parasitologists interested in helping oyster farmers are trying to find novel strategies to combat the disease. P. marinus are found in marine water, and grow especially well in warm waters during the summer months. A pathogen (literally birth of pain from the Greek παθογένεια) is a biological agent that can cause disease to its host. ... The name oyster is used for a number of different groups of mollusks which grow for the most part in marine or brackish water. ...

P. marinus are protozoa, and in particular belong to a group called the alveolates. The individual cells have two flagella, and have a partial polar ring used to attach to their hosts at the anterior. This is similar to structures found among the Apicomplexa, and Perkinsus was previously classified with them. However, genetic studies show that P. marinus is probably closer to the dinoflagellates, which also appear to have modified polar rings. Protozoa (in Greek protos = first and zoon = animal) are single-celled creatures with nuclei that show some characteristics usually associated with animals, most notably mobility and heterotrophy. ... The alveolates are a major line of protists. ... Classes & subclasses Class Conoidasida    Gregarinasina    Coccidiasina Class Aconoidasida    Haemosporasina    Piroplasmasina The Apicomplexa are a large group of protozoa, characterized by the presence of an apical complex at some point in their life-cycle. ... Classes Dinophyceae Noctiluciphyceae Syndiniophyceae The dinoflagellates are a large group of flagellate protists. ...