The body plan is generally centauroid, but much more leonine than equine in appearance. The arms tend to be fairly well muscled. The hands have four digits each, with the last digit on each hand opposite the thumb appearing much more like elongated thumbs than human pinky fingers. The head is large and round, with a vaguely leonine appearance with whiskers and catlike ears, but with a humanlike chin. The nose is actually a flattened single nostril flared at the ends. The feet end in three toes each, with the forefeet having somewhat more prehensile toes. Eyes are catlike, with males having blue eyes and females, golden eyes.
A male Ishtarian is about two metres (6 ft) in height from head to forefeet - about the same as a tall human and the lower torso is about the size of a small horse's. Females are generally shorter in height by about 15 cm (6"), with a slighter build. There is a hump resembling that found on a bull in both sexes, but the female's hump tends to be smoother and not as blocky as a male's. The female has two udders near the genitals on the lower torso to suckle their young. The Ishtarian has a tail, but only males have long tails resembling vaguely that of a lion's; the female has only a short stub for a tail, resembling a cropped dog's tail, but longer. The odor also differs by sex - females have a sweet odor, while males' are acrid. Females have better hearing than males and can also produce a wider range of frequencies in speech.
A striking feature of Ishtarians is that they have a "mane" of red vinelike leaves covering their heads, and the back of the neck and most of the upper torso. They even have "eyebrows" made of a smaller version of these leaves. This is because they are highly symbiotic with plant and microbial life in their bodies. The leaf-mane serves to remove carbon dioxide and other wastes from the body and giving oxygen and certain nutrients in return. This makes for a more efficient metabolism, and the leaves in the leaf-mane can also act as a last-resort food supply.
The skin of Ishtarians is generally smooth and completely hairless. The skin colour of Ishtarians can vary widely from light brown to nearly black. The skin is covered with a tawny-green mosslike growth which aids in nourishing the blood and skin.
Like humans, Ishtarians are omnivores and thus can eat a wide variety of meats and plant matter. Their biochemistry is similar enough to humans that they and humans can each most kinds of either race's native foods. But an Ishtarian would suffer nutritional deficiency disorders if they tried to eat an exclusively human diet. The same goes for a human if he or she tried to eat only Ishtarian foods (fortunately, the human colonists are able to raise their own Earth crops and livestock apparently with little problem). Ishtarians are able to ingest ethanol, and thus brew alcoholic drinks such as beers and ciders of their own.
Ishtarians have much longer lifespans than humans, generally about 300–500 years. They also have a very long period of adolescence, not reaching adulthood until about 64 years of age.
The Ishtarians have a low level of technology, roughly comparable to the Bronze Age on Earth. Roughly every one thousand years, a red giant in a highly eccentric orbit approaches Ishtar closely enough to cause a rise in temperatures. Subsequently, severe weather changes such as droughts and storms occur for over a century. Civilizations collapse during this time as barbarians flee affected lands to plunder better ones. Ishtarians aptly name this period the Fire Time. This, coupled with their long lifespans, has caused them to be locked into their current level of technology for millennia in spite of being a creative and inventive race with greater mental stability than humans.
The northern continent is inhabited by nomads and hunter-gatherers. The southern continent, less affected by the Fire Time, is a more advanced agriculturally based civilization known as the Gathering, with villages along trade routes and shipbuilding is extensive in the southern island arcs.