Diplura

Double tails ( Diplura )

The twin tails (Greek Diplura ) are a class of Hexapod. 15 Of the 500 known species of the group are also common in Central Europe. Most species are 2-5 mm long, the Australian style Heterojapyx Gallardi reached a total length of almost 58 mm. The main dissemination have the double cocks in the tropics and subtropics.

Double dicks live in soil and under stones, leaves and pieces of bark. Some species are also found in the moss, others are den animals. Generally, they are moist loving and photophobia. The members of the Japygidae hunt springtails and live according predatory, other species feed on organic material in the soil or fungal threads.

Construction of the twin tails

The body of the twin tails consists of more or less similar segments, the first three segments ( thoracic ) legs wearing as with all Sechsfüßern. The antennae of the insects are vielgliedrig and consist of members, all of which are furnished with muscles ( limbs antenna). Eyes are missing the double tails completely. The mouthparts are located in a pouch-like structure of the head and can be acute or converted scraping organs.

The abdomen of the animals consists of 10 segments, the first 7 individual segments still carry remnants of the originally present in all segments extremities. The remains are called styli. On the last segment there are two very well-trained and most filamentous caudal appendages Cerci, which are transformed in the Japygidae to strong, single-term pliers. The Projapygidae and some other groups, the Cerci are very short, push -shaped.

Reproduction and Development

The sperm are transmitted indirectly with the double tails. The male is from a pedunculated sperm package ( spermatophore ), which is picked up by a female. Eggs are laid in small burrows as Eiballen, which are hung with some representatives of the Campodeidae by a thread. Some types of Japygidae guard the eggs and hatchlings ( parental care ).

Position of the double cocks in the system

The position of the double tails within the Hexapod is not yet fully understood.

The most common classification of double tails is located within a common group with the springtails and Beintastlern as Sackkiefler ( Entognatha ). The reason for this taxon - Education is the mouth pocket in which the mouthparts are and which is present in all three groups. This Sackkiefler are compared with the Freikieflern or insects as a sister group.

According to an alternative hypothesis ( Kukalová - Peck (1987)) and the Diplura could itself be regarded as a sister group of insects, while a common taxon named Ellipura could in turn be viewed as a sister group of these two groups. As a causative feature here the evolutionarily different number of leg sections is considered, which are fused with the abdominal plates of the abdomen. This feature, and thus the hypothesis is very controversial.