|Publication Type:||Book Chapter|
|Year of Publication:||2009|
|Editor:||Resh, VH, Cardé, RT|
|Book Title:||Encyclopedia of Insects (Second Edition)|
|Pagination:||48 - 50|
Publisher SummaryThis chapter discusses the biography, behavior, and ecology of Archaeognatha. Archaeognatha are apterygote insects with a body size between 6 and 25 mm and a cylindrical shape. The eyes are large and contiguous, and there are two lateral and one median ocelli. The fossil record of Paleozoic and Mesozoic apterygotes is poor, and many of the fossils of ectognathous representatives cannot be clearly assigned to extant orders. The flagellate antennae extend one-half to three times the length of the body. The mouthparts are ectognathous and the mandibles are linked with the head by a monocondylic joint. The mating behavior of archaeognathans is unique. There are three different modes of sperm transfer. Archaeognatha are found in habitats with very different climates. Representatives of the genus Allopsontus are found up to 5,000 m in the Himalayan region. In contrast, two meinertellid species live in the Amazonian forest. Some genera are found near the seacoast. In tropical forests, meinertellid genera are found on the leaves of bushes and trees. Most Archaeognatha feed on green algae, lichens, and dead leaves. Several species of spiders probably are their principal predators. Their protection against enemies is probably provided by three main factors: the presence of long appendages with sensilla; a dense scale cover on the relatively thin and flexible tergites and coxites; and their ability to jump, which is fully developed in all free-living stages and in all recent representatives, and probably is their most effective defense.