Proturans: Protura

Proturans move slowly through the soil with their forelegs, or front legs, held out in front of the head, while the middle and hind legs are used for walking. Some species curl the tip of the abdomen over the head to discharge a sticky fluid in the direction of their enemies. Occasionally, proturans gather together in large groups, making them easy to see.

The life cycles are known only for a few species. Among proturans, there is no courtship, or activities meant to attract a mate. Males deposit packets of sperm on the ground, which are later picked up by the females. Eggs are laid in early spring. Proturans are the only insectlike animals that add body segments and structures as they grow. Larval proturans, or young proturans, look very similar to the adults but have only eight abdominal segments. As they grow and molt, or shed and replace their skeletons, they add segments. Only after they molt for the fifth time do they reach adulthood. It is unknown whether proturans keep growing and molting after they become adults.

Species living close to the surface in cooler habitats produce one generation per year and spend the winter as adults, while species living deep in the soil may reproduce year-round. Some species spend the summer near the surface and migrate deeper into the soil with the approach of winter.