The Hipon resembled giant spiders, although their anatomy more closely resembled that of crustaceans. Their bodies had hard shells, eight hairy legs with inverted joints, and underneath their carapaces were eyes and a round toothless mouth filled with wormlike appendages attached to the upper and lower lips. When nervous, their bodies exuded a brown slime which smelled like rotted fish. They breathed through a gill/lung combination on the sides of their necks. Since their mouths were not connected to their respiratory systems, they were physically incapable of verbal communication. Their form of telepathy, which utilized a strong concentrated beam of psionic energy, was harmful to non-psychic humanoids.
In the 2nd century, the Hipon colonized the southern continent of the planet Fazi, at a time when the natives had not yet begun using tools. It took the Hipon ten years to learn that the Fazi were sentient, but discovered that telepathic communication was fatal to them, and decided instead to keep themselves separate and only feed them information gradually.
In 2151, first contact with humanity and the Hipon was established by Captain Jonathan Archer of the Earth starship Enterprise. After their first two meetings with the Fazi had gone badly, they decided to investigate the Hipon structures on the southern continent. An away team consisting of Travis Mayweather, Elizabeth Cutler and Jamal Edwards was sent there, but when one of the Hipon attempted to communicate with Edwards, inadvertently harming him, it was accidentally beamed aboard along with Edwards. It was confined to sickbay, where it also inadvertently harmed crewmen Pointer and Daniels. The crew studied it and eventually deduced why it seemed to be attacking them, after which they constructed a shield against its psionic energy, enabling Archer to safely communicate with it. (ENT novel: By the Book)