Worms do not technically see, as they do not have eyes. Although worms lack eyes, they have sensitive receptor cells around their bodies that act as sensors by helping worms sense light and vibrations. Worms spend much of their time moving underground, and rely on their sensitive receptor cells to navigate through tunnels and avoid excess exposure to sunlight, which may prove fatal.
Worms are cold blooded. They require certain amounts of sunlight to regulate their body temperatures, like other cold blooded organisms. Worms, however, can only tolerate exposure to sunlight for short periods, roughly 1 hour at a maximum. Excess sun exposure dries out worms' skin, causing paralysis or death.
In addition to sensing light, receptor cells, along with special physiological adaptations, help worms move. Worms lack feet, but navigate underground with the help of bristles, also called setae. These bristles function in several ways, depending on where worms are. Underground and on topsoil, they act as sticky anchors by letting worms grip and slide along tunnel floors. Worms can extend and retract their bristles, and may use them to grip walls, too.
In addition to sensor cells, worms have other adaptations, including the ability to regrow body parts, that facilitate survival. Other physiological adaptations include slime production, which helps worms absorb oxygen, and breathable skin, which keeps them hydrated.