Ah, the Gaper. One of the simplest inhabitants of the Basement, appearing all across every one of its floors.
This creature is one of many "Isaac mimics"- creatures similar in appearance to Isaac that are commonplace throughout the Basement. These Isaac mimics most likely all originate from one common ancestor- Fishaacs being the most likely suspect- and Gapers are the most prevalent of them due to their simplicity and adaptability.
Gapers are omnivorous by nature. As a matter of fact, one of their defining features is their ability to eat nearly anything they're capable of putting in their mouth and chewing without breaking their jaws. They're able to eat not only plants, animals, and fungus, but also waste matter (most notably poop, which is a favored food of theirs) and even some minerals. They will also resort to cannibalism surprisingly quickly, even favoring it over several other food sources.
Additionally, Gapers tend to live in loose packs, roaming around within the same general area and only hunting with other members of their group. The hunting strategy employed by Gapers is a simple one- they walk toward their intended prey in a straight line, only altering their course to avoid obstacles. In this way, large numbers of them are able to overwhelm and devour many creatures they would otherwise be incapable of killing.
When a Gaper's head is cut off of its body, it doesn't die immediately- much like a chicken. Instead, its body stays alive via muscle memory, stumbling blindly around as a Pacer.
Gapers begin life as much smaller creatures known as Morsels. Morsels are for the most part similar to their adult counterparts, but unlike them, they cluster together in much tighter-knit groups, travelling only together with their littermates until they grow from baby Morsels into full-sized Gapers.
After spending some time as Gapers, some members of the species undergo the transformation into a special stage of development, known as a Mr. Horf. A Mr. Horf collects the genetic material of other Gapers by ingesting their bodily fluids- most commonly blood- and uses this genetic material to fertilize and begin the development of new Morsel embryos within its head. During this fertilization period, the Mr. Horf will favor poop as a food source even more than usual.
After around four weeks, when the embryo are only a few days away from fully developing into Morsels, the Mr. Horf will tear its head off of its body- a process aided by the degeneration of the neck tissues, which begins around the same time as fertilization and development- and toss it. The body, as with any other Gaper that loses its head, will continue on for some time as a Pacer, while the head will balloon itself with gases from poop it has consumed and stored over the past four weeks, allowing it to float in the air (this wouldn't normally work, but the Basement's atmosphere possesses strange properties that make being perpetually airborne a much easier process).
These heads, now called Horfs, will simply hover in place for the next few days, spitting excess blood at any potential dangers to themselves, until the Morsels hatch from them, at which point they will fall to the ground and die. Newborn Morsels will often eat the corpse of the Horf that birthed them as their first meal.
There are many subspecies of Gaper, but for now, I'll leave off with that.
