The Gas Bladder

Gas Bladders are strange creatures found in the Underdark drifting between different regions for food. Known for the use of a gas bladder at the top of their bodies to float around the Underdark, they use these to convey basic & very simple warnings, greeting and suchlike to others of their species.

Basic Information

Anatomy

They are floating sacs with a large internal bladder of gas and a stomach. Long tentacles hang below it surrounding a sphincter that leads to the stomach. Everything organic is digested, and everything else is dumped out. Gasses escape through another sphincter on the top that is used to control the bladder size. This allows the Gas Bladder to communicate with others by controlling the amount & chemical composition of the expelled gasses.

Biological Traits

They can be extremely long lived with ones encountered to be thousands of years old, and massive enough to have grown into whole rifts in the floors or roofs of the Underdark. The tentacles are exceptionally long growing up to 10 feet in length for an average sized one, and well over 75 feet for sentient ones.

Genetics and Reproduction

Gas Bladders bud off half a dozen small versions of themselves when reproducing. If they meet others of their kind, they may exchange genetic material that they store under their tough leathery skin until it's time to bud.

Growth Rate & Stages

They start off as small buds that float to an area with a source of water. They then attach to a solid surface nearby waiting for prey to come near. If small enough they will latch on and feed for a while on blood similar to a leech. Then they drop off and slither into a dark hole ore crevice to grow. When large enough, they will take in gas to their bladder and start to float off. Then they start to hunt.

Ecology and Habitats

The Gas Bladders act as scavengers & predators in the Underdark eating any organic matter they find or catch. Since the smell of their gasses and the sound at times a number of creatures learn to avoid them over time, leading them to become almost exclusively scavengers. Other predatory animal sometimes hunt them as prey, letting them get close enough to pounce on them.

Dietary Needs and Habits

Primarily predatory they rely mainly on animal tissue to digest and grow. When this material is lacking they will quite happily feed on plants & fungus living quite happily on it, but taking longer to grow on it alone. If they do eat more of the latter they can easily take in toxins, storing it through their whole body making it sometimes dangerous to attack, breathe in their gasses, get caught in their tentacles, or swallowed.

Biological Cycle

They continue to grow if fed well enough and the largest go one of two ways. Some take up positions high in Underdark caverns & passageways waiting for prey to come close before seizing them in it's tentacles, or the drift down to the floor and flip over into cracks or holes on the floor, squeezing in, and wait for prey to come close.

Behaviour

The Gas Bladders are eating machines. Wherever there is life in the Underdark, there is a number of Gas Bladders nearby. They do work together when prey is plentiful, but will aggressively attack others of their kind if resources are limited. They use their gas bladders to call to one another using pheromones to 'talk' to one another allowing for some coordination or to scare off would-be rivals.

Additional Information

Domestication

So far no-one has been able to tame or train one as the Gas Bladders are just eating machines and will keep growing until nothing short of a warband will bring one down.

Uses, Products & Exploitation

Their bladders, stomach and over bodies have a number of uses to Underdark denizens. The gas bladder is used to trick other Gas Bladders that there is a hostile force into leaving or into a trap. The general smell can be used to mark territory too, to put off any unwanted creatures in a region. Their skin grows thicker with age and the older it is the stronger any leather products is made from it. Sometimes the tissues of one that has ate fungi or plants in a given area will contain highly dangerous toxins that can be used in warfare, for assassinations, or for torture purposes. The stomach acid of a Gas Bladder is extremely potent and strong enough, like a vultures, will destroy virulent disease. This can be used in production of various metallic based objects, alchemy, and magic.

Geographic Origin and Distribution

Spread throughout the Underdark.

Perception and Sensory Capabilities

Sensitive to vibrations & organic compounds in the air and on solid objects, their primitive central nervous system also can detect heat & cold.

Civilization and Culture

History

Nobody knows exactly where the first Gas Bladder came from, just that they are an incredibly ancient species. Many Underdark species tell stories that the Gas Bladders were there far longer than their own species took up residence. Even underground dwelling dragons & Giants mention how old the creatures are saying they remember seeing great herds of them at one stage or another, though have gone down in numbers since others took over & hunted them down.
Their bodies make them targets for many other creatures looking to get toxins, their leathery skin, digestive acids or gas bladders for their own uses. So far they are still abundant enough, but only about half their numbers exist now. They still flourish in regions where little intelligent life exists, and Aboleths sometimes keep a few around to keep the nearby cave systems clean so to speak, and deter unwanted guests.

"Heard some of my clan used to hunt these strange creatures in the Underdark. They are useful for their stomach acids. Powerful stuff indeed lassie. It is used to work metal, for details on armour & weapons. Dangerous it is though so I'd have to be very careful, properly armoured, and uninterrupted. Spill a bit of it on your hand, just a little bit, and you can say goodbye to your while hand & wrist at least."
Childrec Ludger taking to Alfre the Pixie.