Trochozoa protostome bilaterally-symmetric worms {flatworm} (Platyhelminthes) can have mesoderm, have gastrovascular cavities, have muscular pharynx past mouth, and have reproductive organs.
front and back
Bodies have front and back. They keep back upward.
longitudinal
Bodies are longitudinal, with head, trunk, and tail, requiring body orientation. Head is body part that moves first, holds forward senses, and has mouth.
movement
Flatworms move by cilia, using muscular contraction. Muscles have opposing motions and have rhythms controlled by different cells.
nervous system
Flatworms have one brain ganglion with interconnected ventral nerves. Flatworms fused head ganglia to make brain.
Marine-flatworm brain bimodal neurons can habituate to vibration offset, using vibration-sensitive and tactile-sensitive interneurons. They can habituate to illumination offset, using light-sensitive interneurons.
senses
Flatworms have pigmented eyespot cells and can detect light, smell, and touch.
Biological Sciences>Zoology>Kinds>Flatworm
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Date Modified: 2022.0224