Feces

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Not to be confused with facies or excretion.
Elephant feces
Cyclosia papilionaris consuming bird droppings

Feces,"poop", or faeces (see spelling differences), also known as excrement, is waste product from an animal's digestive tract expelled through the anus or cloaca during a process called defecation.

Etymology

The word faeces is the plural of the Latin word faex meaning "dregs". There is no singular form in the English language, making it a plurale tantum.[1] There are many colloquial terms for feces, of which some are considered profane (such as shit) while others (such as poo, poop, number two, deuce, doodoo, dookie, and doody) are not. Terms such as dung, scat, spoor and droppings are normally used to refer to non-human animal feces.

Stool is a common term normally used in reference to human feces. For example, in medicine to diagnose the presence or absence of a medical condition, a stool sample is sometimes requested for testing purposes.[2] The term "stool" can also be used for that of non-human species. In this use, the term stool derives from the noun stool of ease or close stool, a piece of furniture enclosing a chamber pot that could be used during the night and closed afterwards.

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 expelled from its body as waste. Though it is lower in energy than the food it came from, feces may still contain 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, which 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 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 their mother's feces 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, which can locate their prey by their middens and territorial markers.[5]

Seeds may also be found in feces. Animals that eat fruit are known as frugivores. The 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 are often 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 which 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 which plants and other autotrophs may once again absorb. 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.

Human feces

Main article: Human feces

In humans, defecation may occur (depending on the individual and the circumstances) from once every two or three days to several times a day. Extensive hardening of the feces may cause prolonged interruption in the routine and is called constipation.

Human fecal matter varies significantly in appearance, depending on diet and health. Normally it is semisolid, with a mucus coating. Its brown coloration comes from a combination of bile and bilirubin, which comes from dead red blood cells.

In newborn babies, fecal matter is initially yellow/green after the meconium. This coloration comes from the presence of bile alone. In time, as the body starts expelling bilirubin from dead red blood cells, it acquires its familiar brown appearance, unless the baby is breast feeding, in which case it remains soft, pale yellowish, and not completely malodorous until the baby begins to eat significant amounts of other food.

Throughout the life of an ordinary human, one may experience many types of feces. A "green" stool is from rapid transit of feces through the intestines (or the consumption of certain blue or green food dyes in quantity), and "clay-like" appearance to the feces is the result of a lack of bilirubin.

Bile overload is very rare, and not a health threat. Problems as simple as serious diarrhea can cause blood in one's stool. Black stools caused by blood usually indicate a problem in the intestines (the black is digested blood), whereas red streaks of blood in stool are usually caused by bleeding in the rectum or anus.

Food may sometimes make an appearance in the feces. Common undigested foods found in human feces are seeds, nuts, corn and beans, mainly because of their high dietary fiber content. Beets may turn feces different hues of red. Artificial food coloring in some processed foods such as highly colorful packaged breakfast cereals can also cause unusual feces coloring if eaten in sufficient quantities.

Clinical laboratory examination of feces, usually termed as stool examination or stool test, is done for the sake of diagnosis, for example, to detect presence of parasites such as pinworms and/or their eggs (ova) or to detect disease spreading bacteria. A stool culture — the controlled growth of microbial organisms in culture media under laboratory conditions — is sometimes performed to identify specific pathogens in stool. The stool guaiac test (or guaiac fecal occult blood test) is done to detect the presence of blood in stool that is not apparent to the unaided eye. Fecal bacteriotherapy — also known as a fecal transplant — is a medical procedure wherein fecal bacteria are transplanted from a healthy individual into a patient.[6][7]

Human feces collected for a specific practical use, such as for fertilizer, is known as night soil.

Odor

The molecule hydrogen sulfide contributes to the smell of feces.

The distinctive odor of feces is due to bacterial action. Gut flora produce 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 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.[8] Human perception of the odor may be contrasted by a non-human animal's perception of it; for example, an animal that eats feces may be attracted to its odor.

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 and defecate there. Training can be done in several ways, especially dependent on species. An example is crate training for dogs. Several companies market carpet cleaning products aimed at pet owners.

Uses

Manure and fertilizer

Waste container in London, England, 1974
See also: Humanure

Human feces may be used as fertilizer in the form of biosolids (treated sewage sludge). The feces of animals are often used as fertilizer; see manure and guano. In northern Thailand, elephants are used to digest coffee beans for Black Ivory coffee, which is among the world's most expensive coffees.[9]

Bio fuel

Animals such as the giant panda [10] and zebra [11] possess gut bacteria which are capable of producing biofuel. The bacteria, Brocadia anammoxidans, can create the rocket fuel hydrazine from feces.[12][13]

Gut flora transplant

Elephants, Hippos Koalas and Pandas are born with sterile intestines, and require bacteria obtained from their mothers' feces to digest vegetation.[14]

Other uses

See also: Fewmets and Kumalak
Pet waste station at government building

Some animal feces, especially those of camel, bison and cattle, are used as fuel when dried out.[15] Animal dung, besides being used as fuel, is occasionally used as a cement to make adobe mudbrick huts[16] or even in throwing sports such as cow pat throwing or camel dung throwing contests.[17]

Kopi Luwak (pronounced [ˈkopi ˈlu.aʔ]), or Civet coffee, is coffee made from coffee berries which 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.[9]

Dog feces were used in the tanning process of leather during the Victorian era. Collected dog feces 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.[18]

Mycobacterium vaccae is a potentially beneficial mind altering bacteria[19] that was first isolated from cow dung.

Social implications

Feces elicits varying degrees of disgust — one of the basic human emotions — in all human cultures. Disgust is experienced primarily in relation to the sense of taste (either perceived or imagined), and secondarily to anything which causes a similar feeling by sense of smell, touch, or vision. As such, human feces is regarded as something to be avoided diligently: expelled in private and disposed of immediately and without trace. It is often considered an unacceptable topic in polite conversation and its mere mention may cause offence in certain contexts. An example from the ancient world of the repulsion people have felt toward feces is found in Deuteronomy 23:12-14.

12Designate a place outside the camp where you can go to relieve yourself. 13 As part of your equipment have something to dig with, and when you relieve yourself, dig a hole and cover up your excrement. 14 For the LORD your God moves about in your camp to protect you and to deliver your enemies to you. Your camp must be holy, so that he will not see among you anything indecent and turn away from you.[20]

The disposal of feces has always been associated with the lowest people among a society, the social outcasts, the pariahs, and the social discards. The Caste system in India was created along the lines of profession and the dalits (untouchables) were left to do work related to human emissions. They did such work as cleaning and picking feces from streets, cleaning toilets, and working with dead bodies. Such practices are prevalent even today in the rural and small villages of India.

Animal feces

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

The feces of animals often have special names. For example:

See also

References

Notes

  1. ^ "Feces definition – Medical Dictionary definitions of popular medical terms easily defined on MedTerms". Medterms.com. 2012-03-19. Retrieved 2013-11-11. 
  2. ^ Steven Dowshen, MD (September 2011). "Stool Test: Bacteria Culture". Kidshealth. Retrieved 11 February 2012. 
  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. ^ Rowan, Karen (20 October 2012). "'Poop Transplants' May Combat Bacterial Infections". LiveScience.com. Retrieved 2012-10-20. 
  7. ^ Bakken, Johan S.; Borody, Thomas; Brandt, Lawrence J.; Brill, Joel V.; Demarco, Daniel C.; Franzos, Marc Alaric; Kelly, Colleen; Khoruts, Alexander; Louie, Thomas; Martinelli, Lawrence P.; Moore, Thomas A.; Russell, George; Surawicz, Christina (1 December 2011). "Treating Clostridium difficile Infection With Fecal Microbiota Transplantation". Clinical Gastroenterology and Hepatology 9 (12): 1044–1049. doi:10.1016/j.cgh.2011.08.014. PMC 3223289. PMID 21871249. 
  8. ^ 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. doi:10.1098/rsbl.2003.0144. PMC 1810028. PMID 15252963. 
  9. ^ 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. 
  10. ^ USA (2013-09-10). "Panda Poop Might Help Turn Plants Into Fuel". News.nationalgeographic.com. Retrieved 2013-10-02. 
  11. ^ 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. 
  12. ^ Bacteria Eat Human Sewage, Produce Rocket Fuel
  13. ^ Hydrazine Synthase, a Unique Phylomarker with Which To Study the Presence and Biodiversity of Anammox Bacteria
  14. ^ Coprophagia
  15. ^ "Dried Camel Dung as fuel". 
  16. ^ "Your Home Technical Manual – 3.4d Construction Systems – Mud Brick (Adobe)". Archived from the original on 2007-07-06. Retrieved 2007-07-09. 
  17. ^ "Dung Throwing contests". [dead link]
  18. ^ "Rohm and Haas Innovation - The Leather Breakthrough". Rohmhaas.com. 1909-09-01. Retrieved 2012-10-27. [dead link]
  19. ^ Lowry, C.A.; Hollis, J.H.; De Vries, A.; Pan, B.; Brunet, L.R.; Hunt, J.R.F.; Paton, J.F.R.; Van Kampen, E. et al. (2007). "Identification of an immune-responsive mesolimbocortical serotonergic system: Potential role in regulation of emotional behavior". Neuroscience 146 (2): 756–72. doi:10.1016/j.neuroscience.2007.01.067. PMC 1868963. PMID 17367941. 
  20. ^ Deuteronomy 23:12-14, The Bible, New International Version (NIV)

Bibliography

Further reading

External links