Figure 1. Myxobacterial fruiting bodies. Each is a few tenths of a millimeter tall. (a) Myxococcus fulvus (b) Stigmatella aurantiaca (c) Chondromyces crocatus. Dworkin M (1996) Recent advances in the social and developmental biology of the myxobacteria. Microbiological Reviews 60: 70–102.

Figure 2. Life cycle of M. xanthus. A swarm (a group of interacting cells) can have either of two fates depending on the swarm's environment. (a) A Myxococcus fruiting body is a spherical structure of approximately 1×10⁵ cells that contains stress-resistant spores. The fruiting body is small (1/10 mm), sticky and its spores are tightly packed. (b–d) When a fruiting body receives nutrients, the individual spores germinate and thousands of M. xanthus cells emerge together as an ‘instant’ swarm. (e–f) When prey or other nutrient is available, the swarm becomes a predatory collective that moves and feeds cooperatively, pooling extracellular enzymes to lyse and consume prey bacteria. Fruiting body development is highly advantageous given the collective hunting behaviour. Nutrient-poor conditions elicit a unified starvation stress-response that initiates a complex programme of self-organization which changes cell behaviour and leads to the formation of densely packed aggregates. These complex behaviours include wave formation (g), streaming into aggregates (h), mound building (i) and finally sporulation. Goldman BS et al. (2006) Evolution of sensory complexity recorded in a myxobacterial genome. Proceedings of the National Academy of Sciences of the USA 103(41): 15200–15205.

Figure 3. Various types of myxobacterial cells; (a–d) vegetatve cells. (a and b) the Cystobacterineae type. (a) Cystobacter ferrugineus; (b) Stigmatella aurantiaca. (c and d) the Sorangineae type. (c) Chondromyces crocatus; (d) Sorangium compositum. (e–h) myxospores of the Cystobacterineae; (e) Cystobacter ferrugineus; (f) Cystobacter velatus; (g) S. aurantiaca; (h) M. xanthus. Bars=10 m. Shimkets LJ, Dworkin M. and Reichenbach H (2006) The myxobacteria, In: Dworkin M, Falkow S, Rosenberg E, Schleiffer KH and Stackebrandt E (eds) The Prokaryotes, vol. 7, 3rd edn, pp. 31–118. Heidelberg: Springer.