🦠microbiology review

Water molds

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Water molds are filamentous, eukaryotic microorganisms that belong to the class Oomycetes. They thrive in aquatic environments and are known for causing plant diseases.

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5 Must Know Facts For Your Next Test

  1. Water molds possess cellulose in their cell walls, unlike true fungi which have chitin.
  2. They reproduce both sexually and asexually, with asexual reproduction involving sporangia and zoospores.
  3. Phytophthora infestans, a type of water mold, caused the Irish Potato Famine in the 19th century.
  4. Water molds are more closely related to algae and plants than to true fungi based on molecular phylogenetics.
  5. Oomycetes can affect both aquatic animals and terrestrial plants, making them significant agricultural and ecological pathogens.

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