What constitutes a head? InWhat constitutes a head? In alien and otherworldly anatomy the answer may be very different than that which is familiar to us.
The head and neck arrangement as we know it has always seemed to me somewhat maladaptive. With the brain, eyes, ears, nose and mouth all in the head any injury to it is catastrophic. A broken neck or a ruptured trachea or carotid artery are all quickly fatal for a wild animal and easily sustained. The whole assembly could be considered a single point of failure.
So it doesn't seem unreasonable that in a rerun of evolution a different body plan might win out. Perhaps a creature might have a head for eating that can double as a backup respiratory tract, but isn't intimately entwined. A head each for two (or more) eyes as a protection against blindness. They could even have localised visual cortices.
Does it even make sense to have the brain perched up there? Maybe it should be in the centre of the body. Then having multiple heads has no significant impact on neurology.
I think considering the disadvantages of single headed anatomy could help you find a lot of ideas. I hope this small selection helps.
** Ecology ** To put this in an ecological context imagine a savannah watering hole. All manner of creatures must visit it for hydration and many would be at each other's throats, if they have them.
In the real world a drinking animal must lower its entire head to drink, which places its eyes just above the water level. A low bush could conceal a predator.
But if the animal has its mouth on a dedicated extremity then it may lower this to the water while its eyes remain high, granting greater visibility. This is arguably an advantage enjoyed by elephants who use their trunks to transport water to their mouths; a nice precedent.
The eyes could each stand alone, or even four eyes in pairs for all around binocular vision. With its mouth in the water but eyes and nose in the air, the animal would be much harder to sneak up on.
But if this anatomy is established early in evolutionary history then predators could also benefit. Imagine a muscular neck and jaws with sharp teeth buried, vulture like, in a carcass while elevated elevated eyes remain alert to opportunists or its own predators. Out could much more readily turn that powerful maw upon a foe.
High above, fruit eating avian creatures have only eyes in their head. A large brain sits at their centre of mass and a mouth between the shoulders, ready to snap up berries when, perched, the creature uses its over developed eyelids to pick them.