Post-anal tail

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The postanal tail is a muscular tail located behind the anus and (originally) used for locomotion in water . On land, it also takes on a balancing function (e.g. in cats) and / or gripping function (e.g. in primates) for many animals.

It is one of the four synapomorphies (jointly derived basic structural plan features) of the chordates . As a monophylum , it distinguishes it from the closest related tribe of Echinodermata (echinoderms) and the other animal phyla, as their digestive tract usually extends over the entire length of the body and the anus opens at the end of the tail.

In humans, an adult post-anal tail is in most cases regressed ( tailbone ), but it appears embryonic (indication of its evolutionary origin).

literature

  • Neil A. Campbell, Jane B. Reece, Jürgen Markl: Biology . 6th edition. Spectrum Academic Publishing House, 2003, ISBN 3-8274-1352-4 .
  • William K. Purves, David Sadava, Gordon H. Orians, HC Heller: Biology . 7th edition. Spectrum Academic Publishing House, 2006, ISBN 3-8274-1630-2 .