The shape of the Styela plicata digestive tract is "U". The tract includes esophagus, stomach, foreguU midgut, hindgut, rectum and anus.
皱瘤海鞘的消化道为一条“U”形的管道，包括食道、胃、前肠、中肠、后肠、直肠至肛门。
肛门;肛孔
权威例句
1.
The first night, I woke up every hour on the hour, heated the bottles, rubbed the anuses.
NEWYORKER: A Box of Puppies
2.
He checked each dog for a cleft palate and explained that I had to feed them every two hours, and that I should rub their anuses with a hot cloth to express their bowels.