Most spiders have four pairs of eyes on the top-front area of the body, arranged in patterns that vary from one family to another.
The main eyes at the front are capable of forming images.
Jumping spiders have visual acuity which is ten times better than that of dragonflies, which have by far the best vision among insects.
The spiders do this by a telephoto-like series of lenses, a four-layered retina.
They can swivel their eyes and put together images from different stages in the scan.
The downside is that the scanning and integrating processes are relatively slow.

Spiders and other arthropods have modified their cuticles into elaborate arrays of sensors.
Various sensors, mostly bristles, respond to touch, from strong contact to very weak air currents.
Chemical sensors provide equivalents of taste and smell.
Spiders also have in the joints of their limbs sensors that detect forces and vibrations.
In web-building spiders all these mechanical and chemical sensors are more important than the eyes.
The eyes are more important to spiders that hunt actively.
Like most arthropods, spiders lack balance sensors, and rely on their eyes to tell them which way is up.
Most spiders have four pairs of eyes on the top-front area of the body, arranged in patterns that vary from one family to another. The main eyes at the front are capable of forming images. Jumping spiders have visual acuity which is ten times better than that of dragonflies, which have by far the best vision among insects. The spiders do this by a telephoto-like series of lenses, a four-layered retina. They can swivel their eyes and put together images from different stages in the scan. The downside is that the scanning and integrating processes are relatively slow.
Spiders and other arthropods have modified their cuticles into elaborate arrays of sensors. Various sensors, mostly bristles, respond to touch, from strong contact to very weak air currents. Chemical sensors provide equivalents of taste and smell. Spiders also have in the joints of their limbs sensors that detect forces and vibrations. In web-building spiders all these mechanical and chemical sensors are more important than the eyes. The eyes are more important to spiders that hunt actively. Like most arthropods, spiders lack balance sensors, and rely on their eyes to tell them which way is up.
Spider