Beckon anatomy
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Beckon anatomy is the body structure and physiology of Beckons, the stationary Nexus organisms that produce most other parasites. All four species are built on one plan: a flexible spine running from the root crown to the bulb, a body of sealed cells held rigid by internal pressure, a coating of membrane gel, a bulb at the crown that holds most of the organs, and a root mat in the soil that carries the circulation.
In the Adapted Beckon and the two larger species the cells are filled with sulfur hexafluoride, which the organism makes from minerals in the soil. The gas holds the body up, insulates it, stores energy for the winter and is vented to put out fires. In the Primitive Beckon the cells are filled with water, and the gas it makes is released into the air.
Most of what is known comes from dissection and field measurement by the Hyperbiology Division of H&A since 2020. Hyperbiology treats the Beckon as a colony whose organs are specialised members, in the way the parts of a siphonophore are separate animals.
Body plan
Spine
The spine is a column of tough, flexible fibre running the full height of the body, from the root crown below ground to the base of the bulb. It carries the main blood vessels and the main nerve cord, and contains no mineral. Under load it bends without breaking, and it cannot hold the Beckon upright alone: the pressurised cells around it brace it along its whole length, on the principle of inflatable beams built around a strut. A Beckon that loses pressure sags as the unbraced spine bends.
Cells
The trunk and tendrils are packed with sealed cells around the spine, in the arrangement of a closed-cell foam. The cells range from a few centimetres across in small Beckons to about a metre in the largest on Earth. Their walls are living tissue, crossed by blood vessels that branch from the spine to the outer layers. In Adapted Beckons the cells hold sulfur hexafluoride at 1.5 to 3 bar, which is 0.5 to 2 bar above the surrounding air. In Primitive Beckons they hold water. In the other species every gas cell is lined with gas glands, which make sulfur hexafluoride and release it into the cell; in Primitive Beckons the glands lie in the outer tissue and release the gas into the air.
A breach empties only the cells it opens, and the membrane gel flows into the wound and seals it. Valved pores at the base of the trunk can release gas from the lower cells.
Outer layers
Bands of fibre wound in opposing helices around the trunk take the tension of the internal pressure. Over them lies a layer of near-black tissue a few centimetres thick, which absorbs light across the visible spectrum and carries out luxsynthesis. Patches of this layer, and the outer tissue of the bulb, contain a fluorescent pigment and glow green.
Membrane
The outside of the body is coated in membrane gel. It is a suspension of microscopic silica spheres, making up more than half its volume, in a syrup of sugars and glycerol-like alcohols. Under slow force the spheres slide past one another and the gel flows. Under sudden force they jam together across a wide area, and the gel becomes rigid within microseconds. The carrier and the spheres have the same refractive index, and the gel is transparent. Its sugar content keeps it from freezing.
The spheres carry a coat of protein that gives them grip against one another, and the gel hardens only when an impact presses them into contact that friction holds. Heat melts the coat into a slippery film. Spheres that cannot grip cannot lock, and a gel heated at the moment of impact does not harden, which is the principle of RTG ammunition. Sustained heat destroys the coat for good. Proteins dissolved in the carrier set on contact with air, closing wounds in the manner of a blood clot.
Bulb
The bulb, or Assecula Bulbus, sits at the crown and holds most of the organs. It is not pressurised and has no gas cells around it. It is the most vulnerable part of a Beckon at every size. Its outer tissue is the most active light-gathering and glowing tissue in the body.
Tendrils
Tendrils grow from the crown: 4 to 12 in Primitive Beckons, more in specimens on richer soil. They carry the same outer tissue as the trunk and are the main surfaces for light capture and gas exchange. They move slowly, by shifting pressure between their cells.
Root mat
Below ground the Beckon continues as the root mat, a network of strands and vessels in the soil. Around a large Beckon it extends from tens of metres to a few hundred metres, densest in the top metre of soil, and joins the mats of neighbouring Beckons and Dispatchers. The mat digests organic matter outside the body, as fungal mycelium does, and absorbs the products. It holds stored biomass, the brood chambers in which field organisms develop, and the Deterrents of the Dispatchers on it. Digestion in the mat releases ammonia and amines, which give infested ground its smell.
Organs
Heart
The heart lies in the bulb and is the largest organ in it. It contracts once every two to five minutes, and each beat travels out through the mat as a wave of contraction in its vessels, the pulse that can be felt and heard on infested ground. The rhythm resembles the shuttle streaming of slime moulds, which has a similar period.
Blood leaves the heart down the spine to the root mat and returns up the spine. The rising and falling vessels in the spine are rigid and balance each other's weight, and the heart works only against friction. Beckon blood is dark, with a faint glow in the colour of the Beckon's hive. It carries oxygen, nutrients, sulfate and fluoride, and heat, and almost no calcium, which would form fluorite with the fluoride.
Digestive organ
Food reaches the Beckon already broken down by the mat. The digestive organ in the bulb reduces it further to the materials the production organ builds with. Field organisms that return to the Beckon are reabsorbed into the mat with the biomass they have eaten, and are its main source of food.
Filtering organ
All fluid entering from the mat passes through the filtering organ in the bulb before it reaches the rest of the body. The organ removes toxins and metals and stores them, and poisons applied to the soil have little effect on a Beckon. Substances injected into the trunk reach its tissue before they pass through the organ.
Nerve centre
The bulb holds the largest concentration of nerve tissue in the body. It stores the blueprints from which the Beckon produces organisms, in chemical form, and receives revisions of them through the Dispatcher network. It controls the heart, the gas glands, venting and body temperature, and relays signals between the field organisms around the Beckon and the Beckons above it in the chain of command. A main nerve cord runs down the spine, and nerve fibres run through the tendrils and the root mat into the mats of neighbouring Beckons and Dispatchers.
The Beckon senses light, temperature, pressure and touch through its outer tissue, and soil chemistry and vibration through the mat.
Production organ
The production organ in the bulb makes the eggs from which field organisms develop. The eggs are carried down the spine to brood chambers in the root mat, where they grow on stored biomass and emerge from the ground. A Dispatcher on the same mat takes in finished organisms and stores them.
Physiology
Luxsynthesis
Luxsynthesis takes place in the outer tissue. Its black pigment absorbs light across the visible spectrum, and the energy is captured in chemical form and used to build biomass from carbon dioxide and absorbed nutrients. In light the tissue takes in carbon dioxide and gives off oxygen. Luxsynthesis covers the Beckon's running costs; the production of organisms is paid for from stored biomass.
Sulfur hexafluoride
Synthesis. The gas glands make sulfur hexafluoride from sulfate and fluoride carried in the blood. An activating enzyme first joins sulfate to ATP, the same first step taken by every organism on Earth that uses sulfate. The activated sulfate is loaded onto a large enzyme complex, which holds the sulfur atom bound to one of its own amino acids and replaces the oxygen atoms one at a time with fluorine. The complex strips fluoride of its surrounding water before use, as the fluorinating enzymes of some soil bacteria do. The late intermediates react violently with water to form hydrofluoric acid; they remain bound to the complex and never enter the water of the cell, and only the finished gas is released. Each molecule costs about 30 molecules of ATP.
Fluorine supply. Sulfur hexafluoride is 78% fluorine by mass, and a 30-metre Adapted Beckon holds about half a tonne of the gas. Fluoride is scarce in soil water, and the root mat obtains it by dissolving minerals such as apatite and fluorite. Filling an empty Beckon takes one to two years, and replacing gas lost to venting takes weeks to months. Beckons refill fastest on fluorine-rich ground: volcanic soils, granite, farmland that has received phosphate fertiliser for decades, and land downwind of aluminium smelters and brickworks.
Support and insulation. The gas holds the body up. Its large molecules pass through the cell walls far more slowly than those of air, and the cells keep their pressure for years; the same property led to its use for inflating tyres. It conducts heat about half as well as air, and the gas-filled trunk insulates the Beckon in the manner of foam insulation.
Fire suppression. When the outer tissue senses fire, the pores at the base of the trunk open and the lower cells release gas. Sulfur hexafluoride is about five times as dense as air. The vented gas flows down over the base of the trunk and the ground around it, displacing air and absorbing heat, and puts out a small fire within seconds. Each venting uses gas that takes weeks to replace.
Energy storage. Sulfur hexafluoride is chemically unstable in water but reacts with it so slowly that it keeps indefinitely. Its breakdown into sulfate and fluoride releases about 4.6 MJ per kilogram, comparable to the glycogen stores of animals. The gas glands can run in reverse, breaking the gas down and recovering the energy as ATP and heat, and the sulfate and fluoride are kept for later use. Through Overwinter, Adapted Beckons draw on their gas for energy and warmth. An Adapted Beckon uses between a fifth and a third of its gas over an Overwinter and is measurably softer by the end of it, and refills in Upspring and Fullbloom. The gas supplies about a fifth to a quarter of its energy through the winter; the rest comes from stored biomass and winter light.
Body temperature
Adapted Beckons are warm-blooded. They hold the bulb and trunk at 18 to 25 °C in freezing weather. The heat comes from luxsynthesis, from tissue in the bulb that breaks down stored biomass to produce heat, as in the flowers of skunk cabbage and the sacred lotus, and in winter from the breakdown of sulfur hexafluoride. The gas-filled trunk holds the heat in, and in hard cold the tendrils fold over the bulb. In the root mat, warm blood leaving the Beckon passes its heat to cold blood returning to it, as in the legs of wading birds. A gas cell cooled from 20 °C to −10 °C loses a tenth of its pressure, and an Adapted Beckon that cools softens and leans.
Primitive Beckons are cold-blooded. Their temperature follows that of the air and soil, and their growth slows in cold weather. Frost kills them by freezing the water in their cells.
Glow
The green glow of Beckons comes from the fluorescent pigment in the outer tissue of the bulb, the trunk and the root mat. By day the pigment re-emits part of the light the tissue absorbs. At night it is excited by a light-producing chemical reaction in the same tissue, which runs on stored energy, in the way the blue light of the jellyfish Aequorea victoria is converted to green by its fluorescent protein. Both rise with the activity of the tissue, and the brightness of a Beckon is a measure of how active it is. Infested ground glows from the root mat near the surface, as the mycelium of some fungi does. Beckons of each Vagrant's hive carry a variant pigment in that hive's colour, and those of the Knox hive glow purple.
Seasonal cycle
Hyperbiology divides the Beckon year into five seasons, based on its measurements of Beckon growth, output and gas stores. In Upspring growth resumes and the gas cells are refilled. Fullbloom, the longest season, has the highest rates of luxsynthesis, growth and production. In Ingather Beckons stock biomass and gas. Fallow is a short, quieter phase. Through Overwinter Beckons draw on their stored gas and biomass for energy and heat, and continue to produce organisms.
Variation
Species
Primitive Beckons have water-filled cells and a softer body, and can be cut down with hand tools. Their gas glands release the gas into the air instead of storing it, and their blood carries no antifreeze and freezes in a hard frost. Root and Supreme Beckons are built on the Adapted plan at larger scale, and the bulb of the Supreme Beckon of the Iris is kilometres across.
Genome variants
Boreic Beckons, in Siberia, have a denser membrane gel and carry larger gas stores for their size, and remain fully active through Overwinter. Alclidic Beckons, in Australia, carry smaller stores and are more vulnerable to cold.
Control
Beckons are destroyed by attacking the bulb, by fire, or by exhausting their gas. RTG ammunition penetrates the membrane and is the standard munition against Beckons, aimed at the bulb.
Fire works on every species. A sustained fire forces an Adapted Beckon to vent until its gas runs out, after which the trunk burns and the body sags. Field crews commonly burn a Beckon twice, the second time a day or more after the first, before it has replaced the vented gas.
Incendiaries based on magnesium or other reactive metals continue to burn inside a Beckon's gas. Sulfur hexafluoride, which smothers ordinary fires, is a strong oxidiser for these metals, and magnesium releases about as much heat burning in it as in oxygen. A charge of this kind placed inside the trunk cannot be put out by venting.
Trunk injection of sodium molybdate, a cheap industrial salt, stops the gas glands making gas. A treated Beckon cannot refill its cells and breaks down its own gas over the following winter, releasing none, and Federation municipalities use the treatment to clear Beckons in built-up areas, where burning is restricted (see gas gland).
Hazards
Vented sulfur hexafluoride is not toxic, but it has no smell, displaces air, and in still weather collects in hollows, trenches and cellars near Beckon ground, where it can suffocate people. Breathing it lowers the pitch of the voice, which crews treat as a sign of an oxygen-poor atmosphere. Towns next to infested ground in the Federation require oxygen alarms in basements.
In a fire, part of the vented gas breaks down into sulfur oxyfluorides, sulfur dioxide and hydrogen fluoride, with traces of disulfur decafluoride, which is highly toxic. Smoke from a burning Beckon is acidic. Crews burning Beckons wear acid-gas respirators, window glass near a burn is etched, and fluoride damage to crops and livestock has been recorded downwind of large burns.
Beckons are often the tallest objects in a landscape and are frequently struck by lightning. The strike's current runs through the wet outer tissue and blood, and where it arcs through gas cells it breaks down part of the gas; a struck Beckon loses the cells along the path of the strike and gives off acid fumes for about a day.
A Beckon that is burned or dies releases most of its gas into the atmosphere, and Beckons have been the largest source of sulfur hexafluoride on Earth since the mid-2020s. The Federation regulates the emissions of Beckon clearance under its environmental law.
History
Sulfur hexafluoride brought the Beckons to public attention through the sulfur hexafluoride case, the Federation's lawsuit against H&A in 2020, and the gas glands were the first Beckon organ studied in detail. Hyperbiology described their chemistry in 2021, and measured the seasonal drawdown of the gas in 2022; its Beckon seasons are based on those measurements. The reversibility of the glands was established in the same work. Magnesium incendiaries entered service in 2023 and molybdate treatment in 2024.