Final answer:
Cells of the cellular slime molds group, such as Dictyostelium, aggregate and form a moving 'slug' when food is scarce, engaging in phagocytosis to ingest food along the way.
Step-by-step explanation:
When food is scarce, cells of the cellular slime molds group of protists swarm together and crawl as a mass, commonly referred to as a 'slug', ingesting any food they find along the way. A representative genus of cellular slime molds is Dictyostelium. These organisms function as independent amoeboid cells when nutrients are plentiful. However, in conditions of food scarcity, they aggregate to form a multicellular structure that moves as a collective mass to find nutrients, showcasing a fascinating example of cooperation and temporary multicellularity among protists.
Dictyostelium shows that protozoa can adapt to lack of food by changing their behavior and physiology significantly. While most cellular slime molds are harmless, their role in ecosystems is vital as they provide nutrients for other organisms and can also serve as a model for understanding cell communication and differentiation.
Cellular slime molds like Dictyostelium resort to phagocytosis, a type of heterotrophic nutrition, where they engulf whole food particles. This form of nutrition is shared by many protozoans which vary greatly in their means of movement, including the use of cilia, flagella, and pseudopods.