Gas giants are very unlikely paces for life to begin because most are mainly composed of hydrogen and helium. Elements required for conventional life, such as carbon, oxygen and nitrogen, are relatively rare in proportion with the amount of hydrogen and helium present.
It can only be hypothsised that lightning storms in the atmosphere of Ngarep (Ngarep is chosen as the most likely candidate for the origin of Jarum by evolutionary xenobiologists because it is the gas giant with the highest biodiversity out of all of the planets in which the Jarum are present; Ngarep is also in the approximate centre of the sphere in which Jarum have been found to date) were what caused life to begin in its atmosphere. This life was obviously in the form of single-celled micro-organisms at first, which evolved over billions of years into multi-celled organisms, much as life has on Earth.
Most life from Ngarep can be likened to ocean life, except they 'swin' though the atmospheres of gas giants, rather than oceans. As you might expect, this life has to be exceedingly light (and therefore fragile) to be able to float in an atmosphere; this light weight is allowed on a cellular level, as the cells are actually gaseous inside; chemical reactions take place within the gas pocket, which is surrounded by a highly intricate cellular membrane.
The main difference between life in Ngarep and on Earth is that Ngarep life is based on the element silicon, rather than carbon, due to the unusual rarity of carbon in Ngarep's atmosphere compared in silicon. In fact, the whole biochemistry of Ngarep life is different. While the medium of life on earth is water, the medium of life in Ngarep is ammonia; for this reason, proteins found in Jarum are made up of a lot more nitrogen, and a lot less oxygen, than proteins typically found in Earth life.
Arguably the most curious thing about (most) life from Ngarep is that it's medium is gaseous, rather than liquid like on Earth; cellular processes take place in a gas rather than a liquid. The exception to this is near the end of the life cycles of the Jarum (and a few related species), in which they travel deeper into the planet, transferring to a condensed, liquid medium.
Jarum have an uncharacteristically complex life cycle that seems to take them into every level and environment of their gas-giant home. Some have even noted that it seems to reflect how life would likely have evolved on a gas giant in the first place. Still others hypothesise that, due to their sheer size in the later part of their life cycle, Jarum must at some point achieve a high level of sapience.
Worms are considered by most circles to be the first stage in the lifecycle of the Jarum, as they are the stage at which Jarum are at their simplest. Worms are single-celled organisms with a nevertheless highly complex cellular biology, with many organelles that biologists have not found a purpose for yet; they are also uncharacteristically large at many hundreds of microns across, millimetre-scale worms are also not uncommon. However, most ecosystems show us that macroscale single-celled organisms are not uncommon.
Worms are fundamentally symbiotic, as they contain smaller, photosynthetic cells, which use anoxygenic photosynthesis to provide their hosts with the necessary chemicals for cellular functions.
At this point in the Jarum lifecycle, worms are highly variable and adaptable. They also posess a surprisingly thick and resiliant cell wall and cell membrane, which protects the worm from damage due to hostile environments while the cellular biology adapts to the local environment. These membranes restrict the consumption of minerals from the atmosphere; as a result the worms actually shrink in size until the membranes eventually deteriorate and the cell's components have adapted to survive in the local environment.
Worms have no means of locomotion, but drift aimlessly throughout the atmosphere of their home gas giant. They must interact to reach the next stage in the Jarum life cycle, Webs; due to the huge volume of the atmospheres of gas giants, this can take anywhere from years to millennia.
It is thought that Worms must reproduce via cellular fission to make up for population losses during the Worm stage of the Jarum life cycle, though there is no evidence of this actually taking place. When two worms make contact with each other, they stick together; however, worms also posess a slight negative electrical charge which only. This charge possibly produced during metabolic reactions within the cell, in which, instead of dumping extra electrons produced by reactions into waste compounds, the electrons are used to 'over-fill' the electron shells of the atoms that make up the membrane. Further charge likely 'leaks' from the membrane into the gas giant atmosphere.
The charge posessed by the worms prevents tham from sticking together into compact masses, instead causing them to spread out into three-dimensional fractal patters that constantly change as they are disrupted by weather. These patterns have become the subject of a small group of travelling artists, as air trapped within the fractal patterns of the Webs becomes slightly warmer than the surroundings, causing the Webs to rise up into the upper atmosphere of gas giants, making them viewable from orbit using telescopes.
Webs are generally viewed as being colony-organisms, because if they are damaged or break apart, they will eventually re-grow without sign of damage (though two webs can rarely stick together due to their mutual negative charge repelling them from each other). At first, the growth rate of Webs increases as their surface area increases, allowing them to catch more worms. Then, due to the fact that the total negative charge of Webs increases as the Webs get larger, the growth of Webs usually begins to level off at a few hundred metres across, as they become more prone to breaking apart. In exceptional conditions, the largest Webs have been logged as being several kilometres across.
At a certain point in their lives (perhaps determined by the magnitude of their electrostatic charge, which limits their size), Webs undergo a transformation. They gradually turn from highly distributed colony organisms that rely on air currents to stay afloat in the atmospheres of gas giants to much more compact multicellular organisms that use gas density to stay afloat.
Moulds are surprisingly small compared with the Webs they developed from, despite having the same mass; a Mould can be up to thousand times smaller by volume than the Webs they developed from. This presents a problem as it means their surface area is massively reduced, meaning that less energy can be collected from sunlight and there is less surface area to catch air currents to stay aloft.
Moulds therefore have to stay floating in a different manner to Webs, developing an internal gas chamber of hot gases of low density (usually primarily a mixture of hydrogen and helium). Moulds also spread out and flatten so that more surface is presented toward the sun (it has been remerked that Moulds look like blankets or quilts); they very in colour depending on the nature of the star they are under (red stars usually result in black moulds; yellow stars in green or purple moulds; blue stars in yellow or orange moulds), this is a characteristic determined by the first chemical changes in the Worm stage of the life cycle.
Moulds also begin to transition to consuming organisms present in the atmosphere (to make up for the energy deficit caused by the lower surface area for collecting sunlight), often cannibalising Worms or even Webs. This makes Moulds dangerous; there have been accounts of people trying to parachute on top of Moulds, finding that the mould can support their weight, but then being enveloped and digested by the organism.
Moulds appear to have limited locomotion achieved by ejecting gas at high pressure from their float chamber in different directions.
Sinks are sometimes classified as being the same as Moulds, as the transition from Mould to Sink represents no significant change in biology, rather, it is a change in behaviour. One they reach a certain size (this may be from hours to years after the organism becomes a Mould, depending on its size and growth rate), Moulds begin to increase in density and sink into the atmosphere of their gas giant.
Just before it becomes a Sink, a Mould stops consuming food (whether it be produced photosynthetically or directly consumed) and usually reduces in surface area, adopting a more streamlined shape (this is to prevent high winds from blowing the Sink back into the upper atmosphere). The colour of the Mould usually becomes slightly 'washed-out' in this process.
As the organism sinks further into the atmosphere, it gradually has to adapt to the new, more extreme conditions within the gas giant. The rate at which the Sink sinks changes to match the rate of adaptation. It is unknown how extensive the internal changes of a sink are, but by the time it has reached the liquid part of the gas giant's core, it has become a Pseudo-Floater.
Pseudo-Floaters mark the first stage in the Jarum life cycle in which there is little to mention, as at this stage they are so hard to study, being so deep within the cores of their gas giants. All that is known is that a Pseudo-Floater is a kind of intermediate stage which takes place when a sink impacts in the huge ocean of liquid light-elements present below the atmosphere of every gas giant. At this point, the sink becomes inactive, gradually undergoing its transformation into a floater in a cocoon-like state.
Floaters represent a dramatic change in the biology of Jarum; they float on the surface of the liquid part of a gas giant's core. In an ideal world, they would transition directly to Crystallisers, but this is not always possible due to energy constraints. The lucrative amount of energy that can be tapped from the temeperature gradient between the liquid core and the gaseous atmosphere is rarely disused.