Jotoki resemble large, spindly starfish. They have a torochord (ring-shaped) instead of a notochord, with 5 "self-sections" (apparently semi-independent brains) that operate the Jotok's body cooperatively.
The Jotoki begin life as small eel-like aquatic swimmers, most of which are eaten by predators; in time, five of the survivors will merge to form one collective organism, which grows into an arboreal adolescent; its tails become arms, and its fins differentiate into fingers. When it grows large enough, the Jotok imprints itself on an adult (if one is available) and enters a stage of rapid learning and brain growth. Unimprinted adult Jotoki are considered feral, and regarded as little more than animals.
Since the five subunits that make up one Jotok individual are not necessarily genetically related, reproduction does not require sex; a Jotok can simply find a pond and deposit its offspring to begin the cycle again. A Jotok who desires a family can simply go into the wilderness and "harvest" an adolescent of the proper age (a property that Kzin slavers later exploit).
Before their enslavement, Jotoki operated in groups called "clanpods", as part of their former planet-wide tradeweb. Details of this arrangement are not known. Jotok technological specialties included gravity polarizers, linguistics and biotechnology. They had the ability to force-grow clones to adulthood.
The Jotoki were also experts at trade. Their interstellar trade empire was quite developed for its time, but when the Jotoki attempted to use the Kzin as mercenaries, the Kzin revolted and conquered the Jotoki. In "modern" times (i.e. during most of the Known Space stories), Jotoki are a seldom-seen slave race of the Kzinti. The Kzinti believe that there is a free Jotoki fleet wandering amongst the stars, which would have provided their most strenuous opposition (excepting humans).
Surviving Jotoki swimmers inhabited a swamp near a crashed Kzin cruiser. Although the swamp was rendered uninhabitable, by the end of the book it is established that humans recovered some Jotoki and are attempting to breed a free Jotok species.