Ramicristates

Ramicristates
Scientific classification
Kingdom: Protista Taxon: Ramicristates
Classes & Orders
Class Mycetozoa     Liceida     Echinosteliida     Trichiida     Stemonitida     Physarida     Protosteliida Acanthamoebida Dictyosteliida Stereomyxida Leptomyxida Euamoebida Arcellinida Trichosida Euglyphida Amphitremida

The Ramicristates are a large group of amoeboid protists, including most forms with lobose and filose pseudopods. They are united by the presence of branching tubular cristae within their mitochondria, which gives them their name, and appear to share a common origin. All undergo open mitosis without centrioles, but most characters show some variation within the group. The most famous member is Amoeba proteus, which is often studied as a representative unicellular organism.

Many members of this group produce shells. These may be relatively simple secreted shells, as in Arcella, shells covered in sand grains and other collected detritus, as in Difflugia, or shells covered in internally formed siliceous scales, as in Euglypha. Some are fairly structured, though not nearly as ornate as those found in some other amoeboid groups.

The true slime molds, or Mycetozoa, belong here. These grow to form a multinucleate plasmodium, which in some may reach several square feet in size. Eventually this produces one or more fruiting bodies or sporangia, superficially similar to those found in fungi. The spores develop into biflagellate gametes, which fuse to form new sporangia. The Dictyosteliida also form fruiting bodies, but these are formed by aggregates of separate amoebae which come together under unfavorable circumstances rather than individual plasmodia. Similar life styles are found in other unrelated groups, collectively referred to as cellular slime molds.