Slime molds are eukaryotic organisms that share characteristics of both protozoa and fungi. They can be divided into two main categories - cellular slime molds and acellular slime molds.

Cellular slime molds are singular organisms with ameoba like cells. A well known example is Dictyostelium, which is used by many biologists as a system for biochemical experimentation. Dictyostelia have an interesting life cycle. They spend most of their time in a vegetative state, but at some point, they all join together and form a large mass which grows a stalk known as a fruiting body. This then releases spores. When dictyostelia are starved, they will fuse together and form a larger organism known as a pseudoplasmodium. They do not lose their individuality but solidify into a large, slimy migrating mass known as a slug. At some point, the slug stops moving and becomes vertically oriented. This then grows into the stalk and head of the fruiting body.

Acellular slime molds are naked masses of protoplasm known as plasmodia. They feed mostly on other microorganisms, particularly bacteria. They are usually found on decaying matter such as rotting logs. They also form fruiting bodies in order to reproduce.

See also: syncitium Myxomycota