part_of part of part of distalmost_part_of develops_from develops from orifice proctodeum anus http://upload.wikimedia.org/wikipedia/commons/6/65/Protovsdeuterostomes.svg http://upload.wikimedia.org/wikipedia/commons/7/75/Anorectum.gif MA:0000331 MESH:A03.492.411.495.767.288 anal orifice WBbt:0005364 Orifice at the opposite end of an animal's digestive tract from the mouth. Its function is to expel feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest, such as bones; food material after all the nutrients have been extracted, for example cellulose or lignin; ingested matter which would be toxic if it remained in the digestive tract; and dead or excess gut bacteria and other endosymbionts. FMA:15711 UBERON:0001245 Wikipedia:Anus GAID:312 anal TGMA:0001279 galen:Anus BTO:0001680 EV:0100082 TADS:0000066 FBbt:00003148 uberon proctodeum UMLS:C0003461 In the lungfish, sharks and rays the rectum opens into the cloaca which also receives wastes (urine) from the kidneys and material from the reproductive organs. In bony fish the rectum reaches the outside environment through the anus, which is normally situated just in front the urinary and reproductive openings. However in some fish the digestive tract may be curled back on itself, and in the Electric Eel (Electrophorus electricus) the anus is situated in the fish's throat. -- http://www.earthlife.net/fish/digestion.html CALOHA:TS-2005 NCIT:C43362 SCTID:181262009 opening of terminal part of digestive tract anal opening OpenCyc:Mx4rvVjaEZwpEbGdrcN5Y29ycA digestive tract ectoderm-derived structure