Mouthparts are entognathous and are greatly modified between genera. The first pair of legs are used as antennae and have many tarsal sensilla and sensory hairs. Genital opening is between the eleventh segment and the telson. Life History Unique among hexapods, Protura exhibit anamorphosis, i.e., the larvae hatch with a few abdominal segments with the number increasing with subsequent moults. The embryology is unknown.
All proturans have five distinct stages.
One family, Acerentomidae, has six. The eggs of only a few species have been recorded. The prelarva is hatched with nine abdominal segments and weakly developed mouthparts. Larva I also has nine abdominal segments with fully developed mouthparts. Larva II is the third stage and has an additional segment added between the telson and the eighth.