Fungus-Like Protists

• Fungus-like protists can't make their own food so they need to move to find it. These protists have filaments similar to those that make up the mycelium of fungus, but on fungi, these are white, while on protists, they are brightly colored. Fungus-like protists that you'd find on dead or rotting trees act as decomposers, breaking down the decaying tree into material that is useful to other organisms. Fungus-like molds found on dying trees include slime molds and downy mildews.
  
  

Slime Molds

• Slime molds live in moist soils and decaying plants and are typically very bright in color. Slime molds are single-celled, but can be colonial, joining together when necessary to act as multicellular organisms. When they do this, they form sporangia, which consist of a cluster of live cells on top of a stalk made up of dead cells. The stalk lifts the live cells up toward more desirable conditions. When sporangia are no longer needed, the cells separate and return to single-celled organisms. Slime molds thrive in decayed wood, moving in and around the fibers and feeding on bacteria.
  
  

Downy Mildew

• Water molds are part of the protest division called oomycetes. This group of protists includes white rusts and downy mildews, which are often found on rotting trees. They are typically parasitic and cover the surfaces of leaves and stems of the plants they infect. Often these protists play a role in the tree's death.
  
  

Plant-Like Protists

• Plant-like protists are able to make their own food and some may live in the soil as well as on the barks of trees. They can also be found in fresh and salt water. These protists produce oxygen, which is critical to the aquatic food chain. Most plant-like protists are photosynthetic like plants, and may have stem-like and anchoring structures that resemble plants, but they do not have actual stems and roots. The plant-like protists typically found on decaying trees include yellow-green and green algae.
  
  

Yellow-Green Algae

• Chrysophytes are a division of plant-like protists that include diatoms, golden algae and yellow-green algae. They are unicellular and photosynthetic, often found in toothpaste and filters. Yellow-green algae is often found on rotting trees and is named for its color. It is unable to move and doesn't have a cell wall, but does have flagella that enables it to move if it has to. Yellow-green algae is found in most aquatic environments.
  
  

Green Algae

• The most similar of all plant-like protists to actual plants, green algae is found in several forms. Although most are unicellular, some green algae live in colonies, while a few are multicellular. Green algae grows below the soil, on rocks as well as on tree bark. It can also be found growing on the surface of the ocean and other marine water, in snow and in other organisms.