The Zarbi resembled giant ants. Some Zarbi moved on two powerful human-like legs, (TV: The Web Planet) while others, like the ones in the London Underground, moved on six legs like ants on Earth. (COMIC: Prisoners of Time) They communicated by screeching and rubbing their legs together. (TV: The Web Planet) Much like bees, Zarbi also communicated by dancing. (COMIC: The Macrobe Menace) They were naturally simple-minded creatures, no smarter than cattle. They had no individual motives. (TV: The Web Planet)