Question

Complete the following descriptions of the general anatomy and physiology of a planarian, a free-living flatworm.

a) Respiration occurs through __________.
b) Excretion is mainly through __________.
c) Movement is facilitated by __________.
d) Nutrition is primarily __________.

Answer 1

Respiration in planarians occurs through diffusion, excretion is mainly through tubules and excretory pores, movement is facilitated by cilia, and nutrition is primarily obtained through a gastrovascular cavity.

Step-by-step explanation:

a) Respiration occurs through diffusion across the outer membrane of the flatworm's body.

b) Excretion is mainly through a network of tubules connected to flame cells, which direct waste fluids concentrated in the tubules out of the body through excretory pores.

c) Movement is facilitated by the presence of cilia on the intake end of the excretory tubules that propel waste matter down the tubules.

d) Nutrition is primarily obtained through a branching gastrovascular cavity, which is used for digestion and distribution of nutrients throughout the body.