Shadow Spiders

The Shadow Spiders of The City in Flux are one of the more horrifying and terrible things to be found in a city already crawling in a bevy of nastiness. As their name suggests, they are arachnids which cannot exist in either pure light, or the emptiest of blackness, but instead are only found where light and dark mingle. They can be found across nearly the entire city (seeing as they are immaterial, to varying degrees), but in most of it they present nothing more than a vague annoyance, unless of course you happen to be an arachnophobe. Basically act like spiders everywhere else in the real world, with two important exceptions. One is the fact that they never cease growing throughout their lives, so long as they can maintain a steady diet, leading, in rare circumstances, to the creation of true monsters. The other, of course, is the reason for their name. In addition to only being able to appear in places of shaded light, Shadow Spiders also appear to be made of shadows themselves. As they grow larger they grow more corporeal, but even at their largest documented sizes they are never fully solid. Babies, ranging in size from several inches to a foot or two, are barely there, and have trouble interacting with much at all. As such, it is hard for them to grow much bigger than that, except in extenuating circumstances. After reaching a size greater than a foot or two in length however, they can grow rapidly if the environment is right, and in many of the shaded, cramped alleys of the city, they are just that. In some cases the only thing preventing a full-out spiderpocolypse is the fact that the true monstrosities cannot venture out of their lairs to hunt anymore for lack of enough shade to house them, leaving to sit, waiting for full shadow to fall on their entire body once again so that they may come out and feed.
There are several sections of the city where proper maintenance has not been kept up however, and their the spiders reign. After enough time without proper food however, they tend to shrink in size, leading to vagrants and lower members of society re-colonizing these areas, until the last few spiders large enough to do so begin feeding on their sleeping forms and ballooning in size once again. Regular lighting of all of the city would of course prevent such occurrences, but that would require a far higher level of organization, and far lower level of corruption than is present in the city, or will be present in it for the forseable future.

Basic Information

Anatomy

Like a normal spider in shape and function, Shadow Spiders continue to grow throughout their lives, and it is unclear if they are capable of dying of old age. Unlike normal spiders, they can only exist in shadow, and when exposed to either bright light or pure darkness they disappear. When shadows return to the place where the vanished from however, the spider will return, as if no time had passed for it. Even when present on this plane, they and their webs are partially immaterial. The larger a specimen grows, the more physical its form however. It is not until they grow to the size of a large cat or small dog that they can interact with enough of the real world to begin hunting most vertebrates however.

Ecology and Habitats

They have only been extensively documented in @Flux as of yet, which is probably for the best. Some poorer, more run-down neighborhoods have been basically taken over by them, however in most of the city they are small nuisances, and nothing more. Rooftops at night and narrow alleyways during the day are their preferred habitats.

Dietary Needs and Habits

Shadow Spiders are known to eat all manner of prey, so long as it is still alive. When at their smallest, they can only prey on insects and the like. In the rare cases that one is able to grow large enough, it will start preying on small children, sleeping vagrants, and sometimes, in the rarest and most nightmarish of cases, fully grown adults. Their paralytic venom allows them to keep prey "alive" enough for feeding for extended periods of time, and as a result they do not need to hunt especially often. If prey and shadows are available however, there does not appear to be a practical limit on how much they CAN eat. The only side effect of such gluttony is a rapid growth in said spider, without apparent limits, seeing as they are not natural creatures, and do not have normal bodies constrained by conventional biology. There have been documented scenarios where one or two spiders gained access to large stores of living victims in a short period and were able to balloon to truly terrifying proportions in an extremely short period of time.

Biological Cycle

When the shadow a spider is living in vanishes, the spider vanishes with it. Researchers have been unable to determine where it vanishes to, although some posit they return to whatever plane of shades they are native to. Once the shadow reappears however, in sufficient dimensions to house the entirety of the spider that was there before, it reappears, none the worse for wear. As such, they tend to be most active in the hours of dawn and dusk, when shadows are the longest and most prolific, and most rare during the darkest of nights and brightest of days. Overcast days are also especially good for them. Otherwise the seasons don't appear to affect them much.

Geographic Distribution