eye spot - A dent lined with photosensitive cells. It is only capable of detecting the direction of light, not of creating images.
pharynx - The animal grasps food by extending it.
gastrovascular cavity - It plays an important role in both digestion and the distribution of nutrients to all parts of the body. This is necessary because flatworms do not have a separate circulatory system.
paired ganglia - This is where most of the nerve cells are located. Through evolution nerve cells became concentrated in the head of organisms, as most of the stimuli affect this body part. This process is called cephalisation. Planaria show an early stage of cephalisation.
lateral nerve bundles
transverse nerve bundles
ovary - It produces eggs.
testis - It produces sperm.
yolk gland - It secretes the yolk of the egg, which contains cells and substances that surround, protect and nurture the zygote.
copulatory sac - During copulation the sperm is stored here.