(i) Their bodies are long, cylindrical and slender.
(ii) The upper part of the body is open and the lower part is closed.
(iii) Twisted hypostome is located at the free end of the body.
(iv) Hypostome has 6–8 scutes.
(v) One or more buds are present on the body
(vi) At the lower end of the body is the foot-disc.