part_of part of part of develops from Homo sapiens orifice proctodeum anus http://upload.wikimedia.org/wikipedia/commons/6/65/Protovsdeuterostomes.svg http://upload.wikimedia.org/wikipedia/commons/7/75/Anorectum.gif 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 anal digestive tract ectoderm-derived structure