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Feces

From Wikipedia, the free encyclopedia
Elephant feces
Human feces
A comparison of elephant (left) and human feces (right)

Feces or faeces (British and Latin) are the solid or semisolid remains of the food that could not be digested in the small intestine, but has been rotted down by bacteria in the large intestine.[1][2] It also contains a relatively small amount of metabolic waste products such as bacterially altered bilirubin, and the dead epithelial cells from the lining of the gut.[1] It is discharged through the anus or cloaca during a process called defecation. Urine and feces together are called excreta.

Collected feces has various uses, namely as fertilizer or soil conditioner in agriculture, as a fuel source, construction material, or for medicinal purposes (fecal transplants or fecal bacteriotherapy, in the case of human feces).

Ecology

The cassowary disperses plant seeds via its feces
Earthworm feces aid in provision of minerals and plant nutrients in an accessible form

After an animal has digested eaten material, the remains of that material are discharged from its body as waste. Although it is lower in energy than the food from which it is derived, feces may retain a large amount of energy, often 50% of that of the original food.[3] This means that of all food eaten, a significant amount of energy remains for the decomposers of ecosystems. Many organisms feed on feces, from bacteria to fungi to insects such as dung beetles, who can sense odors from long distances.[4] Some may specialize in feces, while others may eat other foods as well. Feces serve not only as a basic food, but also as a supplement to the usual diet of some animals. This is known as coprophagia, and occurs in various animal species such as young elephants eating the feces of their mothers in order to gain essential gut flora, or by other animals such as dogs, rabbits, and monkeys.

Feces and urine, which reflect ultraviolet light, are important to raptors such as kestrels, who can see the near ultraviolet and thus find their prey by their middens and territorial markers.[5]

Seeds also may be found in feces. Animals who eat fruit are known as frugivores. An advantage for a plant in having fruit is that animals will eat the fruit and unknowingly disperse the seed in doing so. This mode of seed dispersal is highly successful, as seeds dispersed around the base of a plant are unlikely to succeed and often are subject to heavy predation. Provided the seed can withstand the pathway through the digestive system, it is not only likely to be far away from the parent plant, but is even provided with its own fertilizer.

Organisms that subsist on dead organic matter or detritus are known as detritivores, and play an important role in ecosystems by recycling organic matter back into a simpler form that plants and other autotrophs may absorb once again. This cycling of matter is known as the biogeochemical cycle. To maintain nutrients in soil it is therefore important that feces return to the area from which they came, which is not always the case in human society where food may be transported from rural areas to urban populations and then feces disposed of into a river or sea.

Characteristics

Fresh bear scat showing a diet of apples
Bear scat showing consumption of bin bags in garbage

The distinctive odor of feces is due to bacterial action. Gut flora produces compounds such as indole, skatole, and thiols (sulfur-containing compounds), as well as the inorganic gas hydrogen sulfide. These are the same compounds that are responsible for the odor of flatulence. Consumption of foods prepared with spices may result in the spices being undigested and adding to the odor of feces.

The perceived bad odor of feces has been hypothesized to be a deterrent for humans, as consuming or touching it may result in sickness or infection.[6] Human perception of the odor may be contrasted by a non-human animal's perception of it; for example, an animal who eats feces may be attracted to its odor.

Human feces

Depending on the individual and the circumstances, human beings may defecate several times a day, every day, or once every two or three days. The extensive hardening that interrupts this routine for several days or more is called constipation.

The appearance of human fecal matter varies according to diet and health.[7] Normally it is semisolid, with a mucus coating. A combination of bile and bilirubin, which comes from dead red blood cells, gives feces the typical brown color.[1][2]

After the meconium, the first stool expelled, a newborn's feces contain only bile, which gives it a yellow-green color. Breast feeding babies expel soft, pale yellowish, and not quite malodorous matter; but once the baby begins to eat, and the body starts expelling bilirubin from dead red blood cells, its matter acquires the familiar brown color.[2]

At different times in their life, human beings will expel feces of different colors and textures. A stool that passes rapidly through the intestines will look greenish; lack of bilirubin will make the stool look like clay.

Pets

Sign ordering owners to clean up after pets, Houston, Texas, 2011

Pets can be trained to use litter boxes or wait to be allowed outside to defecate. Training can be done in several ways, especially dependent on species. An example is crate training for dogs. Several companies market cleaning products for pet owners whose pets have soiled carpets in the home.

Uses of animal feces

Fertilizer

The feces of animals often are used as fertilizer; see guano and manure.

Energy source

Dry animal dung is used as a fuel source in many countries around the world by burning it. Some animal feces, especially those of camel, bison, and cattle, are used as fuel when dried.[8]

Animals such as the giant panda[9] and zebra[10] possess gut bacteria capable of producing biofuel. The bacteria, Brocadia anammoxidans, can create the rocket fuel hydrazine from feces.[11][12]

Coprolites and paleofeces

A coprolite is fossilized feces and is classified as a trace fossil. In paleontology they give evidence about the diet of an animal. They were first described by William Buckland in 1829. Prior to this they were known as "fossil fir cones" and "bezoar stones". They serve a valuable purpose in paleontology because they provide direct evidence of the predation and diet of extinct organisms.[13] Coprolites may range in size from a few millimetres to more than 60 centimetres.

Paleofeces are ancient human feces, often found as part of archaeological excavations or surveys. Intact feces of ancient people may be found in caves in arid climates and in other locations with suitable preservation conditions. These are studied to determine the diet and health of the people who produced them through the analysis of seeds, small bones, and parasite eggs found inside. These feces may contain information about the person excreting the material as well as information about the material. They also may be analyzed chemically for more in-depth information on the individual who excreted them, using lipid analysis and ancient DNA analysis. The success rate of usable DNA extraction is relatively high in paleofeces, making it more reliable than skeletal DNA retrieval.[14]

The reason this analysis is possible at all is due to the digestive system not being entirely efficient, in the sense that not everything that passes through the digestive system is destroyed. Not all of the surviving material is recognizable, but some of it is. Generally, this material is the best indicator archaeologists can use to determine ancient diets, as no other part of the archaeological record is so direct an indicator.[15]

A process that preserves feces in a way that they may be analyzed later is called the Maillard reaction. This reaction creates a casing of sugar that preserves the feces from the elements. To extract and analyze the information contained within, researchers generally have to freeze the feces and grind it up into powder for analysis.[16]

Other uses

Pet waste station at government building

Animal dung occasionally is used as a cement to make adobe mudbrick huts,[17] or even in throwing sports such as cow pat throwing or camel dung throwing contests.[18]

Kopi Luwak (pronounced [ˈkopi ˈlu.aʔ]), or civet coffee, is coffee made from coffee berries that have been eaten by and passed through the digestive tract of the Asian palm civet (Paradoxurus hermaphroditus). Giant pandas provide fertilizer for the world's most expensive green tea.[19] In Malaysia, tea is made from the droppings of stick insects fed on guava leaves.

In northern Thailand, elephants are used to digest coffee beans in order to make Black Ivory coffee, which is among the world's most expensive coffees.[19]

Dog feces were used in the tanning process of leather during the Victorian era. Collected dog feces, known as "pure", "puer", or "pewer",[20] were mixed with water to form a substance known as "bate." Enzymes in the dog feces helped to relax the fibrous structure of the hide before the final stages of tanning.[21]

Elephants, hippos, koalas and pandas are born with sterile intestines, and require bacteria obtained from eating the feces of their mothers to digest vegetation.

Terminology

Cyclosia papilionaris consuming bird droppings

Feces is the scientific terminology, while the term stool is also commonly used in medical contexts.[22] Outside of scientific contexts, these terms are less common, with the most common layman's term being poo (or poop in North American English). The term shit is also in common use, although is widely considered vulgar or offensive. There are many other terms, with some of the more widely used being crap, dump, load and turd.[23]

Etymology

The word faeces is the plural of the Latin word faex meaning "dregs". In most English-language usage, there is no singular form, making the word a plurale tantum;[24] out of various major dictionaries, only one enters variation from plural agreement.[25]

Synonyms

"Feces" is used more in biology and medicine than in other fields (reflecting science's tradition of classical Latin and New Latin)

  • In hunting and tracking, terms such as dung, scat, spoor, and droppings normally are used to refer to non-human animal feces
  • In husbandry and farming, manure is common.
  • Stool is a common term in reference to human feces. For example, in medicine, to diagnose the presence or absence of a medical condition, a stool sample sometimes is requested for testing purposes.[26]
  • The term bowel movement(s) (with each movement a defecation event) is also common in health care.

As with urine, there are many synonyms in informal registers for feces. Many are euphemismistic, colloquial, or both; some are profane (such as shit), whereas most belong chiefly to child-directed speech (such as poo or poop) or to crude humor (such as deuce or turd). It is also represented in emoji form in the Miscellaneous Symbols and Pictographs block of Unicode as U+1F4A9 💩 pile of poo, called unchi or unhci-kun in Japan.[27][28]

Horse feces

The feces of animals often have special names, for example:

Society and culture

Feelings of disgust

In all human cultures, feces elicit varying degrees of disgust, a basic human emotion.[citation needed] Disgust is experienced primarily in relation to the sense of taste (either perceived or imagined) and, secondarily to anything that causes a similar feeling by sense of smell, touch, or vision.

See also

References

  1. ^ a b c Tortora, Gerard J.; Anagnostakos, Nicholas P. (1987). Principles of anatomy and physiology (Fifth ed.). New York: Harper & Row, Publishers. p. 624. ISBN 0-06-350729-3. 
  2. ^ a b c Diem, K.; Lentner, C. (1970). "Faeces". in: Scientific Tables (Seventh ed.). Basle, Switzerland: CIBA-GEIGY Ltd. pp. 657–660. 
  3. ^ Biology (4th edition) N.A.Campbell (Benjamin Cummings NY, 1996) ISBN 0-8053-1957-3
  4. ^ Heinrich B, Bartholomew GA (1979). "The ecology of the African dung beetle". Scientific American. 241 (5): 146–56. doi:10.1038/scientificamerican1179-146. 
  5. ^ "Document: Krestel". City of Manhattan, Kansas. Retrieved 11 February 2012. 
  6. ^ Curtis V, Aunger R, Rabie T (May 2004). "Evidence that disgust evolved to protect from risk of disease". Proc. Biol. Sci. 271 Suppl 4 (Suppl 4): S131–3. PMC 1810028Freely accessible. PMID 15252963. doi:10.1098/rsbl.2003.0144. 
  7. ^ Stromberg, Joseph, ...Nine surprising facts about feces..., Vox, Friday, January 23, 2015
  8. ^ "Dried Camel Dung as fuel". 
  9. ^ "Panda Poop Might Help Turn Plants Into Fuel". News.nationalgeographic.com. 2013-09-10. Retrieved 2013-10-02. 
  10. ^ Kathryn Hobgood Ray (August 25, 2011). "Cars Could Run on Recycled Newspaper, Tulane Scientists Say". Tulane University news webpage. Tulane University. Retrieved March 14, 2012. 
  11. ^ Bacteria Eat Human Sewage, Produce Rocket Fuel
  12. ^ Harhangi, HR; Le Roy, M; van Alen, T; Hu, BL; Groen, J; Kartal, B; Tringe, SG; Quan, ZX; Jetten, MS; Op; den Camp, HJ (2012). "Hydrazine synthase, a unique phylomarker with which to study the presence and biodiversity of anammox bacteria". Appl. Environ. Microbiol. 78: 752–8. PMC 3264106Freely accessible. PMID 22138989. doi:10.1128/AEM.07113-11. 
  13. ^ "coprolites - Definitions from Dictionary.com". 
  14. ^ Poinar, Hendrik N.; et al. (10 April 2001). "A Molecular Analysis of Dietary Diversity for Three Archaic Native Americans". PNAS. 98 (8): 4317–4322. PMC 31832Freely accessible. PMID 11296282. doi:10.1073/pnas.061014798. 
  15. ^ Feder, Kenneth L., Linking to the Past: A Brief Introduction to Archaeology. New York: Oxford University Press, 2008. Print.
  16. ^ Stokstad, Erik (28 July 2000). "Divining Diet and Disease From DNA". Science. 289 (5479): 530–531. doi:10.1126/science.289.5479.530. 
  17. ^ "Your Home Technical Manual – 3.4d Construction Systems – Mud Brick (Adobe)". Archived from the original on 2007-07-06. Retrieved 2007-07-09. 
  18. ^ "Dung Throwing contests". Archived from the original on October 11, 2007. 
  19. ^ a b Topper, R (15 October 2012). "Elephant Dung Coffee: World's Most Expensive Brew Is Made With Pooped-Out Beans". The Huffington Post. Retrieved 10 December 2012. 
  20. ^ "pure". Oxford English Dictionary (3rd ed.). Oxford University Press. September 2005.  (Subscription or UK public library membership required.) n., 6
  21. ^ "Rohm and Haas Innovation - The Leather Breakthrough". Rohmhaas.com. 1909-09-01. Archived from the original on October 19, 2012. Retrieved 2012-10-27. 
  22. ^ http://medical-dictionary.thefreedictionary.com/stool
  23. ^ http://www.heptune.com/poopword.html
  24. ^ "Feces definition – Medical Dictionary definitions of popular medical terms easily defined on MedTerms". Medterms.com. 2012-03-19. Retrieved 2013-11-11. 
  25. ^ Houghton Mifflin Harcourt, The American Heritage Dictionary of the English Language, Houghton Mifflin Harcourt. 
  26. ^ Steven Dowshen, MD (September 2011). "Stool Test: Bacteria Culture". Kidshealth. Retrieved 11 February 2012. 
  27. ^ "The Oral History Of The Poop Emoji (Or, How Google Brought Poop To America)", Fast Company, November 18, 2014 
  28. ^ DAMON DARLIN (March 7, 2015), "America Needs Its Own Emojis", The New York Times 
  29. ^ Meyer-Rochow V.B., Gal J (2003). "Pressures produced when penguins poo - calculations on avian defaecation". Polar Biology. 27: 56–58. 

External links

  • MedFriendly's Article on Feces
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