The body flat purse like structure with length of 6-13 cms. Breadth is 4-7 cms. Colour is brownish. The animal is pretty buried in sand by means of foot. The body proper has two projections-atrial and branchial siphons. Branchial siphon has a branchial or incurrent aperture or mouth. The atrial siphon has atrial or excurrent aperture or cloaca. Each aperture is surrounded by four lobesorlips. The whole body is covered by thick leathery and translucent Tunicortest. The same is wrinkled. It is formed of cellulose like organic substances known as tunicin.
Herdmaniaisfilterorciliary feeder. Digestive tract is complete. Liver and pyloric glands are present. Respiration is with the help of branchial sac. Water enters the body from the region of mouth or branchial aperture, passes through the pharynx where food is picked up. It comes out through atrial aperture. The current is maintained by cilia lining the gill slits. Water current also helps in gaseous exchange.
When disturbed, Herdmania emits a jet of water through both of its apertures. The animal is hermaphrodite. Cross fertilisation occurs which is external. Larval stage or tadpole undergoes retrogressive metamorphosis to become an adult.
^Sanamyan, K. (2015). Herdmania Lahille, 1888 . In: Shenkar, N.; Gittenberger, A.; Lambert, G.; Rius, M.; Moreira Da Rocha, R.; Swalla, B.J.; Turon, X. (2015) Ascidiacea World Database. Accessed through: World Register of Marine Species on 2015-12-29.