The nervous system of earthworms
The common earthworm has both a PNS and a CNS. Its main nervous system structure consists of two ganglia which are above the mouth, on either side. These ganglia are connected to one common nerve cord which runs down the length of its back. There are large amounts of chemoreceptors in the worm. These are concentrated near the worm's mouth. In the earthworm's PNS, there are longitudal and circumfrential muscles on each annelid segment. These muscles on the outside are what allows the worm to move.
Fun facts
There are a few chords in the worm's nervous system, but there is only one main nerve cord.
The 13 main parts of the worm's nervous system are anus, intestine, cerebral ganglion, prostomium, mouth, nerve collar, segmental ganglion, pharynx, esophagus, segmental nerve, crop, gizzard, and ventral nerve cord.
Worms have no vertebrae, but they maintain their "skeletal structure" using fluid in sacs which are spread throughout their body.
The 13 main parts of the worm's nervous system are anus, intestine, cerebral ganglion, prostomium, mouth, nerve collar, segmental ganglion, pharynx, esophagus, segmental nerve, crop, gizzard, and ventral nerve cord.
Worms have no vertebrae, but they maintain their "skeletal structure" using fluid in sacs which are spread throughout their body.