Spirochetes, Myxobacteria, and Cyanobacteria [take a quiz on this topic]

Chapter Seven: The Classification of Unicellular Organisms General classification of organisms Spirochetes, Myxobacteria, and Cyanobacteria Algae Euglenas Chrysophytes and Pyrrophytes Protozoa Phyla Mastigophora and Sarcodina Phyla Sporozoa and Ciliophora

Spirochetes
One important class of bacteria consists of spiral-shaped cells called spirochetes. Although these heterotrophs may be aerobic or anaerobic, they share the common distinct spiral feature.

Spirochetes (image courtesy of Thad Stanton)

They hold their shape through the means of special flagella called axial filaments which the cell wraps itself around, resulting in a spiral shape. In order to move, the axial filaments are rotated, the spiral turns, and the organisms swims along. Among the many varieties, one class of spirochetes is transmitted by fleas and causes Lyme disease.

Myxobacteria
The name myxobacteria is derived from the slimy mucus-like secretion which they release. The prefix myxo is equivalent to the word mucus; hence the name, myxobacteria. Most of them live in soil rather than an aquatic environment. They do not possess flagella but are able to glide through the use of strange fibrils on the inside of the cell. Myxobacteria are heterotrophic aerobic organisms.

One of the most interesting aspects of myxobacteria is their method of reproduction. Unlike most prokaryotes which reproduce simply by division, myxobacteria first form large structures called fruiting bodies which may have between thousands and millions of organisms. Some of the cells in the fruiting body divide, and the daughter cells come together to form what are called cysts, small groups of cells which are released into the environment. When a cyst finds an environmentally-friendly location, the cells divide and grow.

Cyanobacteria
Cyanobacteria are prokaryotic organisms sometimes referred to as blue-green algae. They are autotrophic and utilize photosynthesis, using a type of chlorophyll called chlorophyll a. Cyanobacteria, which can be aerobic or anaerobic, are in many ways the most advanced class of prokaryotes in that they possess specialized membranes which help perform specific functions, especially those devoted to photosynthesis. However, they do not possess flagella like many other prokaryotes do.

One interesting aspect of cyanobacteria is that they often form sophisticated colonies in which different cells actually perform certain roles. These colonies usually can form in any wet environment, including the ocean and freshwater lakes.