Against Which of the Following Do the Circular and Longitudinal

Question

Against which of the following do the circular and longitudinal muscles of annelids work?
A) cuticle
B) shell
C) endoskeleton
D) hydrostatic skeleton

Accepted Answer

The circular and longitudinal muscles of annelids work against the hydrostatic skeleton. This type of skeleton is formed by a fluid-filled cavity, the coelom, which provides the resistance needed for muscle contraction, allowing movement and flexibility.