The brain is used to relay sensory information to other parts of the body and to help with movement. The first ventral ganglion is used primarily to control movement of the mouth. The segmental ganglia throughout the length of the grasshopper are connected to the first ventral ganglion by a double nerve cord and serve to coordinate local activities. Each ommatidia is like an individual lens that samples a small part of the visual field. There can be thousands of ommatidia in a single insect eye.
Some insects are sensitive to ultraviolet light and others can detect infrared wavelengths of light.
Octopus The octopus has the most complicated brain of all the invertebrates. The octopus brain is estimated to have 300,000,000 neurons. These neurons are arranged in lobes and tracts that are more specialized than simple ganglia. The eye of the octopus is very similar to that of vertebrates in that it has a cornea, lens, iris and retina. It can also focus and form images.