Cercus
As Cercus (from ancient Greek κέρκος kérkos , German , tail ' ; also Afterraife , Analraife , after probe , Raife ) are the paired abdomen attachments in the last abdominal segment Tracheentieren called, so in the Sechsfüßern ( insects , springtails , diplura and protura ) and millipedes . The majority of these are spoken of as the cerci.
Layout and function
The cerci represent the extremities of the last abdominal segment in front of the telson and are also present in many taxa in which there are no or only rudimentary extremities on the remaining abdominal segments. Cerci are originally long, articulated and thread-shaped and equipped with many whiskers, so that they serve as tactile organs, similar to antennae .
In many groups they have been modified and taken on a different form and different functions. In the case of earwigs , dragonflies and representatives of the double tails ( Japyx ), for example, they form gripping tongs. In springtails , they are designed to be a jump fork . In some forms, some of the whiskers also function as auditory hairs ( sensillae ) in the form of trichobothria , for example in cockroaches .
In many groups within the insects the cerci are completely absent or only present in rudimentary form.
Other abdominal appendages
In some groups of insects, such as the mayflies , there is another abdominal appendage that arises unpaired at the telson. This is known as the terminal filum . In addition, dragonfly larvae, for example, have so-called anal valves , consisting of an unpaired epiproct and two paraprocts . Beetle larvae can have cerci-like structures on the 9th abdominal segment, which are called urogomphi , corniculi or pseudocerci.
Web links
supporting documents
- ↑ a b c d Herder Lexicon of Biology . CD-ROM. Spektrum Akademischer Verlag, Heidelberg 2003, ISBN 3-8274-0354-5 , keyword “Cerci”.