AP BIOLOGY

Detailed explanation-1: -It does have a nerve net, but these are connected by long nerve cords. These cords are connected to cerebral ganglia located in the head region. The central nervous system has been described as “ladder-like” because of the nerves connecting the nerve cords.

Detailed explanation-2: -The bilaterally flattened body of flatworms preserves a common organization of the central nervous system (CNS). The CNS of flatworms consists of: (i) the orthogon, composed of main longitudinal nerve cords and transverse commissures that form a ladder-like network.

Detailed explanation-3: -Flatworms have a cephalized nervous system that consists of head ganglion, usually attached to longitudinal nerve cords that are interconnected across the body by transverse branches. Excretion and osmoregulation by flatworms is controlled by “flame cells” located in protonephridia (these are absent in some forms).

Detailed explanation-4: -Flatworms have a ladder-like nervous system; two interconnected parallel nerve cords run the length of the body. Most flatworms have a distinct head region that includes nerve cells and sensory organs, such as eyespots.

Detailed explanation-5: -The ancient flatworms were the first animals to develop a central nervous system and a head with a brain.