From Simple English Wikipedia, the free encyclopedia
Snout?vent length
(
SVL
) is the length of an animal's body. It is measured from the tip of its
snout
to its rear end. The snout is the part of the face at the front. Snout-vent length does not count the tail or any teeth or tusks.
[1]
So, in a frog, it is the length of the frog's body but not the frog's legs. For turtles, scientists use carapace length (CL, the length of the shell) and plastral length (PL) instead.
The SVL can change depending on whether the animal is alive, dead, moving, or still. It can change if scientists have used chemicals to stop its dead body from rotting.
[2]
Scientists also use snout-vent length on
fossils
. With fossils, they use
osteological correlate
, which is a way the bone can match the rest of the body. Precaudal length is one osteological correlate. A scientist can look at the animal's SVL, weight, and body and may be able to tell if it is male or female or how old it is.
[3]
Scientists use snout-vent length instead of the animal's whole body length because it does not change much. In some animals, young ones do not have tails or do not have large tails.
[4]
The scientist or other person can measure snout-vent length with
dial calipers
or
digital calipers
.
The scientist can use other tools to hold the animal still. For example, snake tubes, "Mander Mashers,"
[5]
or a "Salamander Stick."
[6]
The term is useful for
mammals
. It's not so useful for animals where the tail is an important part of the body. For example, fish have tails that are parts of their bodies. But horses and elephants use their tails to hit flies but not much else. Dinosaurs that
walk on two legs
are a good example too. It took a long time for
dinosaur scientists
to understand this. Snake tails go far past their vent.
- ↑
"direct line distance from tip of snout to posterior margin of vent"
Watters, Jessa L.; Cummings, Sean T.; Flanagan, Rachel L.; Siler, Cameron D. (2016).
"Review of morphometric measurements used in anuran species descriptions and recommendations for a standardized approach"
.
Zootaxa
.
4072
(4): 477?495.
doi
:
10.11646/zootaxa.4072.4.6
.
ISSN
1175-5334
.
PMID
27395941
.
- ↑
Vitt, Laurie J.; Zug, George R. (2012).
Herpetology: An Introductory Biology of Amphibians and Reptiles
. Academic Press. p. 34.
ISBN
978-0127826202
.
- ↑
Kupfer, A. (2007). "Sexual size dimorphism in amphibians: an overview". In Fairbairn, D. J.; Blanckenhorn, W. U.; Szekely, T. (eds.).
Sex, Size, and Gender Roles: Evolutionary Studies of Sexual Size Dimorphis
. New York: Oxford University Press. pp.
50
?59.
ISBN
978-0-19-920878-4
.
- ↑
Bolton, Melvin (1989).
"7. Capture, Transport, Marking and Measuring of Young Crocodiles"
.
The management of crocodiles in captivity
. FAO.
- ↑
Wise, S. E.; Buchanan, S.W. (1992). "An efficient method for measuring salamanders".
Herpetological Review
.
23
: 56?57.
- ↑
Walston, L. J.; Mullin, S. J. (2005). "Evaluation of a new method for measuring salamanders".
Herpetological Review
.
36
: 290?292.