the termite gut membrane to be digested later. Mixotricha forms a mutualistic relationship with bacteria living inside the termite. There are a total of four species of bacterial symbionts. It has spherical bacteria inside the cell, which function as mitochondria, which Mixotricha lacks. Mixotricha mitochondria degenerated and lost the ability to produce energy aerobically by oxidative phosphorylation. Mitochondrial relics include hydrogenosomes which produce hydrogen and small structures called mitosomes. Ectosymbionts for movement Three surface colonising bacteria are anchored on the surface. The flagella and cilia are actually two different single celled organisms. The ciliate belongs to an archaic group that used to be called archezoa but this term is no longer in fashion. It has four weak flagella, which serve as a rudder. While Mixotricha has four anterior flagella, it does not use them for locomotion, but more for steering. For locomotion, about 250,000 hairlike Treponema spirochaetes, a species of helical bacteria, are attached to the cell surface and provide the cell with cilia-like movements. The wavelength of the cilia is about and suggests that the spirochaetes are somehow in touch with each other. Mixotricha also has rod-shaped bacteria arranged in an ordered pattern on the surface of the cell. Each spirochaete has its own little emplacement, called a 'bracket'. Spirochetes move continuously forwards or backwards but when they are attached they move in one direction. Sperm tails might have their origin in spirochaetes. The evidence that cilia (undulipodia) are symbiotic bacteria is found unpersuasive. Genome Mixotricha have five genomes, as they form very close symbiotic relationships with four types of bacteria. It is a good example organism for symbiogenesis and nestedness. There are two spirochete and one-rod bacteria on its surface, one endosymbiotic bacteria inside to digest cellulose and the host nucleus. References Metamonads Symbiosis Endosymbiotic events