Anatomy
A nerve net is a diffuse network of cells that can congregate to form ganglia in some organisms, but does not constitute a brain. There are two categories of nerve cells that are found in the nerve nets of hydra: ganglion and sensory. While ganglion cells are normally found near the basal ends of the epithelial cells, sensory cells generally extend in an apical direction from the muscle processes of the basal ends.
There are many subsets of neurons within a nerve net and their placement is highly position specific. Every subset of a neuron has a constant and regional distribution. In a hydra, cell bodies of epidermal sensory cells are usually found around the mouth at the hypostome’s apical tip, neurites are usually directed down the sides of the hypostome in a radial direction, and ganglion cells are found in the hypostome’s basal region (in between tentacles and just below the head).
Read more about this topic: Nerve Net
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“Man is a shrewd inventor, and is ever taking the hint of a new machine from his own structure, adapting some secret of his own anatomy in iron, wood, and leather, to some required function in the work of the world.”
—Ralph Waldo Emerson (1803–1882)