Head to torso length

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The head-trunk length is a body measurement and describes the length of a terrestrial vertebrate from the tip of the snout or nose to the base of the tail. The measure is used especially in mammals . To measure, the body of the animal is stretched out on its back on a flat, horizontal surface and gently pressed and straightened, but not overstretched. The forehead and nose are pressed against the surface.

The actual tail root, the joint between the sacrum and the first caudal vertebra , lies between the pelvic wings and can only be exposed through a skin incision and the removal of connective and muscle tissue . This is too expensive, especially when examining large series. Therefore, the anus or the externally visible root of the tail are often used as the rear measuring point , which can lead to deviating and more fluctuating dimensions. In old-world mice, for example, the anus is often only located below the fourth to sixth caudal vertebra. In addition, the tail, which is under a certain tension due to muscles and tendons , even in dead animals, can not be bent at right angles, especially at its point of attachment.

Sufficiently accurate measurement results cannot usually be obtained on living animals. Measurements on freshly dead animals are recommended, but measurements during rigor mortis are not recommended. After rigor mortis, the body can be easily overstretched due to slack ligaments , so that the length then measured is usually greater than immediately after death. The determined head-torso length can fluctuate with repeated measurements even by the same person. In the case of mice, fluctuations of a few millimeters cannot be excluded.

In some cases, the head-torso length is subtracted from the measured total length in order to determine the tail length . In fish , the standard length is used to indicate the length of a fish from the foremost end of the animal to the base of the caudal fin.

literature

  • Doris Freudig, Rolf Sauermost (Ed.): Lexicon of Biology. Volume 12: Reso to Sim . Spektrum Akademischer Verlag (Elsevier), Heidelberg 2003, ISBN 3-8274-0337-5 .
  • Martin Görner, Hans Hackethal: Mammals of Europe: Observe and determine . Ferdinand Enke / Deutscher Taschenbuch-Verlag, Stuttgart / Munich 1988, ISBN 3-432-96461-7 (licensed edition).
  • Joachim Jenrich, Paul-Walter Löhr, Franz Müller: Small mammals: body and skull features. Ecology . Michael Imhof, Fulda 2010, ISBN 978-3-86568-147-8 .
  • Erna Mohr: The free-living rodents in Germany and neighboring countries . 3. Edition. VEB Gustav Fischer, Jena 1954.
  • Jochen Niethammer, Franz Krapp (Hrsg.): Handbook of mammals in Europe. Volume 1: Rodents I . Akademische Verlagsgesellschaft, Wiesbaden 1978, ISBN 3-400-00458-8 .
  • Matthias Schaefer: Brohmer: Fauna of Germany . 21st edition. Quelle & Meyer, Wiebelsheim 2002, ISBN 3-494-01326-8 .

Remarks

  1. ↑ According to Freudig and Sauermost, 2003 (“Tail”), fish do not have a tail morphologically.
  2. ↑ a b c d e Niethammer and Krapp, 1978 (p. 46)
  3. ↑ Schaefer, 2002 (p. I)
  4. ↑ a b c d e Jenrich and coworkers, 2010 (p. 16)
  5. ↑ Mohr, 1954 (p. 73)
  6. ↑ Mohr, 1954 (pp. 73–74)
  7. ↑ Görner and Hackethal, 1988 (pp. 12-13)
  8. ^ Mohr, 1954 (p. 76)
  9. ^ Niethammer and Krapp, 1978 (p. 43)