Feces, faeces, or fæces (see spelling differences) is a waste product from an animal's digestive tract expelled through the anus (or cloaca) during defecation. The word faeces is the plural of the Latin word fæx meaning "dregs". There is no singular form in the English language, making it a plurale tantum.

Etymology

Due to the nature of feces, several synonyms have developed. Of these, some are generally used as profanity (such as shit and crap) while others have been deemed inoffensive (such as poo, poop, dookie, and turds). Other terms (such as dung and droppings) are normally used for animal feces rather than human feces.

Ecology

Feces are also important as a signal. Kestrels, for instance, are able to detect the feces of their prey (which reflect ultraviolet), allowing them to identify areas where there are large numbers of voles.

Seeds may also be found in feces. Animals which eat fruit are known as frugivores. The advantage in having fruit for a plant 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: 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. 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.