Anal pyramid

The end of the abdomen with the anal pyramid in an empty sample of the blue-green maidenhead ( Aeshna cyanea )

The anal pyramid is an anatomical feature of the larvae of the dragonfly (Anisoptera), consisting of the totality of the abdominal appendages . These are the unpaired, dorsal epiprocts and the paired, ventral paraprocts , which are arranged around the anal opening and together form the anal valves , as well as the paired cerci . These abdominal appendages are thorn-like in the larvae and are mobile.

The epiproct and the paraproct can be put together to form a pyramid-like unit. A tube is formed in the interior of this pyramid by channel-like depressions.

function

The anal pyramid of the dragonfly larvae has different functions. Due to their strong, thorn-like formation, the thorns can be used as a weapon against potential attackers as well as against prey animals that defend themselves. Since the dragonfly larvae perform an anus breathing with the help of their rectal gills , the tube that is created when the appendages are folded can be used as a breathing tube , with which older larvae in particular can take in oxygen outside of the water like a snorkel . Long hair on the inner surfaces of the epiproct and the paraproct also cleans the respiratory water by sifting out dirt particles like a net. The tube has a further function in rapid locomotion, as the larvae can swim over long distances by means of expelled breathing water in accordance with the recoil drive and thus flee from threats, for example.

supporting documents

1. ↑ ^{a b c d} Keyword “Anal pyramid” In: Herder-Lexikon der Biologie . Spektrum Akademischer Verlag GmbH, Heidelberg 2003, ISBN 3-8274-0354-5 .
2. ↑ G. Jurzitza: The Kosmos dragonfly guide . Franckh-Kosmos, Stuttgart 2000; P. 35, ISBN 3-440-08402-7 .
3. ↑ Andreas Thomas Hein | Berlin and Brandenburg: Trachea | LibellenWissen.de. (No longer available online.) Archived from the original on June 15, 2017 ; accessed on May 8, 2017 (German). Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.