Slime mold

Slime molds are various kinds of protists that have an amoeboid body form and, like fungi, reproduce by spores produced within fruiting bodies. Traditionally they were studied both by zoologistss as amoebae and by mycologistss as fungi. They are now treated as several separate groups in the kingdom Protista.

In true or plasmodial slime molds, called Mycetozoa or Myxomycetes, the feeding stage generally takes the form of a multinucleate amoeba, called the plasmodium. Spores are produced in sporangia, aethalia, or sporocarps, and give rise to biflagellate gametes called swarmers that fuse to form new plasmodia. Some reach several feet in size, and many are brightly colored. However, most are only visible as tiny sporangia or as plasmodia growing to produce them, and so although they are genuine cosmopolitans they are rarely noticed.

It has been observed that plasmodia can find the shortest route through a maze, by means of spreading out along all possible paths and then taking the best one, an interesting example of sophisticated information processing without a nervous system.

In Finland one particular unusually prominent slime mold with a yellow plasmodium (Fuligo septimia) was supposedly used by witches to spoil a neighbours milk, called "paranvoi" (trans. butter of the familiar spirit).

Other groups are called cellular slime molds. They usually exist as individual amoebae, but under stress these aggregate to form a colony or pseudoplasmodium, which migrates to a better location and then forms into a fruiting body. Spores release new amoebae. There are two groups, the dictyostelids and acrasids, which show several differences in life cycle and are not closely related. A similar life cycle has also appeared among the myxobacteria. Some other protists that form cellular aggregates have also been considered slime molds, such as the labyrinthulids and plasmodiophorids.