Water mold

The water molds or Oomycota are a group of filamentous protists, which are superficially similar to the fungi, and were originally classified as such. However they are not actually related to them, and show a number of important differences, such as having diploid nuclei in their vegetative state and lacking chitin within their cell walls. Instead they belong among a group called the stramenopiles, which also includes brown algae, diatoms, and the like. One characteristic that water molds show in common with other stramenopiles is the typical heterokont pattern found in flagellate cells.

The water molds include a number of important parasites, including the potato blight, which was a major cause of the Irish potato famine.