Final answer:
Tunicates have an excretory system consisting of nephridia that filter waste materials and release them outside of the body.
Step-by-step explanation:
Tunicates, also known as sea squirts, have an excretory system composed of sac-like organs called nephridia. Nephridia filter waste materials from the body fluids and release them outside of the body. The waste is expelled through an opening called the cloaca or the excurrent siphon. Nephridia in tunicates function similarly to the nephridia in earthworms, as they also filter fluid and remove waste products before excretion.