Proturans do not have eyes or antennae. Ametabola lacking metamorphosis eggs hatch into young which are smaller than adults, but similar in appearance. All of these families are similar in ecology and habitat. Proturans do not have eyes or antennae. The front pair of legs are usually held in front of the body and apparently serve as sensory organs.
All gas exchange occurs through the integument.
With only about 500 species worldwide, Protura is the smallest class in the phylum Arthropoda.