I've taken quite a liking to the concept of aliens, especially some of the aliens that I've seen in science fiction. This has sparked me to invent my own aliens and the planets they live on. Perhaps some day I'll put up information on those specific alien species and their planets. For now, I would like to show you some of the ideas that I have had for fictional extraterrestrials, as well as ideas that I have derived from others. Perhaps you are a creative mind who enjoys projecting what weird life might live on other worlds. In that case, maybe my list will work as a guide to help inspire you. I will try to update this page over time, adding more ideas to the list.
Before I proceed any further, I would like to say that aliens won't be animals, plants, fungi or bacteria. Scientists have produced quite a rigorous set of classification rules for the life forms on Earth. Whether an organism is classified in kingdom Animalia, Plantae, Fungi, etc, depends on the characteristics of its cells. These features include the presence or absence of chloroplasts, membrane-bound organelles, certain proteins and carbohydrate storage facilities, among others. Aliens may have cellular characteristics that are similar to that of animals, plants, fungi or bacteria, but they would ultimately be classified in different kingdoms, such as paranimalia, alloplantae, etc. Because they come from other worlds, they won't be related to the life forms on Earth and therefore should not be classified in the kingdoms thereof. However, there are a few terms that you may see me using:
- Animaloid - I use this to refer to aliens that are "like animals" in that they are motile during at least part of their life cycle, and cannot produce their own food. They may be carnivores, herbivores, omnivores, etc.
- Plantoid - I use this to refer to aliens that are "like plants" in that they are usually sessile and produce their own food from some outside energy source. This term may encompass some protist-like aliens as well.
These ideas really only encompass those life forms which are "physical" in nature. I tend to shy away from "energy-based" beings or "ultraterrestrials" because we have no idea how they would function. Chemistry-based lifeforms are the only things that we have a real example of, so I tend work from there. Now then, here is a list of possibilities:
COVERING
- Epidermal Gas Pockets - For warm-blooded creatures, temperature regulation can be quite important. In birds we see a covering of feathers to provide insulation. In mammals, fur is used for the same purpose. Although there may be examples of aliens with fur and feathers, I would prefer to use a different type of integument (outer covering) in a designed alien, for originality purposes. It may yet be possible to think-up a covering that provides insulation that is neither fur nor feathers.
One of my ideas was the use of numerous air pockets just underneath the skin of an animaloid. These air pockets would be covered by a thin, perhaps even dead, layer of epidermal tissue that makes the animaloid look as if its body is covered from head-to-toe in tiny bubbles. This is reminiscent of the air pockets one might find on a pizza crust. These air pockets contain some gas, perhaps air or nitrogen excreted by the internal organs. The purpose of these pockets is to separate the outside environment from the underlying layers of the animaloid. The still air in these pockets serves as a kind of insulation, much like still air-space underneath feathers serves the same purpose in birds. In a cold environment, the outside air would have to cool down the air in these pockets before it could chill the tissue layers of the animal. This delay in temperature change would help the creature maintain homeostasis.
These pockets might be ruptured if the animaloid were to sustain injury from a predator, which would be detrimental to their insulation requirements. However, the animaloid could shed damaged air pockets and grow new pockets underneath their skin. If the tissue covering the pockets is living, then they could merely repair the pockets in a similar manner to healing a cut. Tiny pockets would be more difficult to rupture than large ones, but they have less heat-controlling capacity than large ones do. This would lead to a trade-off in pocket size depending on the species of organism that possesses them. We might expect predators to have larger pockets than prey, for instance.
- Photosynthetic "Fur" - Much as mammals have a coat of insulating fur to keep them warm, we may expect aliens to have a similar mechanism for temperature regulation. In this case, I propose the possibility of a symbiotic relationship in which the "fur" of an animaloid is actually a distinct organism in itself; a plantoid. We could think of an animaloid that has strands of tissue protruding from its skin, which covers its body to form a protective layer of insulation. Each strand would actually be a plantoid, similar in shape to blades of grass on Earth, but likely much smaller.
These plantoids, which I call "phur" (short for "photosynthetic fur") would be imbedded in the animaloid's epidermal layers, drawing water, carbon dioxide, and minerals from the animaloid's blood via root-like projections. These nutrients, in addition to a source of light like their planet's Sun, would allow them to produce their own food. As well as being a source of nutrients, the animaloid would also serve as a mobile unit for the phur, allowing it be readily moved from place to place, aiding in dispersal of spores or seeds. Being on an animaloid would offer protection against herbivorous life forms too.
Obviously, there must be some trade-off for the animaloid as well, or the phur would just be a parasite. This is where the insulating properties of phur comes in. It can keep the animaloid (which is presumably warm-blooded) warm during times when temperature regulation is needed for survival. It can also help the animaloid by aiding in the removal of toxic carbon dioxide from its blood. The coloration of the phur may be useful in the animaloid's interactions with members of its own species, in which it can be used as a visual identification tool. It can help in the mating rituals too (the males with the best-developed phur indicate that they are healthy).
How the phur would get into an animaloid's skin in the first place is an interesting question with different possible answers. Perhaps the animaloids are social creatures that care for their young. By keeping them around and raising them, it allows spores from an adult's phur to land on their bodies and launch roots into their skin. Over time, the spores develop into a mature coat of phur. Another method may be for the release of spores from the phur into a pregnant animaloid's blood. The spores travel to the developing embryo inside of the animaloid, and implant themselves in the epidermis. They stay dormant until the animaloid is born, whether hatched from an egg or born alive, upon which time photosynthesis allows them to grow.
HABITATION
- Atmosphere - On Earth, life forms have been known to live permanently on land, or indefinitely in water. However, we have yet to discover complex life forms that dwell endlessly in the atmosphere (some bacteria do, however). An aerial ecosystem would be quite intriguing, and would be home to life with exotic anatomies.
Start off with a source of energy, like some kind of aerial plantoid. The plantoid is shaped like a balloon, with a photosynthetic membrane on its surface. By collecting atmospheric water vapor, it uses photosynthesis to break it down into hydrogen and oxygen. The oxygen is released, but the hydrogen is used to fill its body cavity, thus providing buoyancy. Atmospheric animaloids may use this plantoid as a kind of home, where they can rest in between flights. The herbivores may also eat them as a source of food.
Perhaps these animaloids would have two pairs of wings. One pair flaps to propel the creature through the sky while the other pair rests. Whenever one pair gets tired, it switches to using the other pair that has been resting, thus allowing them to stay aloft for virtually indefinate time periods. The animaloids might also implement a similar mechanism as the plantoids, where they have hydrogen-filled, balloon-like bodies. Wings could still provide motility, but they wouldn't be need them to stay air-borne. The hydrogen in their bodies would be obtained from the plantoids through ingestion.
- Vacuum - A vacuum is any place that is devoid of, or mostly devoid of, gases or other materials. Outer space is generally described as a vacuum. The surface of atmosphere-less planets is also where a vacuum is present. Aliens living on an airless world would need to have quite a few adaptations to survive.
Since there is no oxygen or other oxidizing gases to inhale, the aliens must use anaerobic respiration. This tends to provide much less energy than aerobic respiration, and thus may greatly limit the size and complexity of these aliens. Also, their growth rate would likely be very slow. The aliens would need a hard, armor-like integument to prevent their internal fluids from evaporating into space. Their skins must also be very resistant to changes in temperature, since the difference between night and day temperatures would be typically large.
Since there are no hydrographics on an airless world (they would boil away), the aliens must find liquid through other methods. Perhaps they would be able to tap into underground pockets of water via a long proboscis or roots. They may also be able to produce water by extracting hydrogen and oxygen from rocks and then reacting them together with enzymes.
Walking on this world would be no problem, but flight would be. Without air, wings cannot provide lift and are therefore useless. Some of these aliens may have a form of jet propulsion, similar to the Bombadier Beetle on Earth. This would allow them to jump large distances and perhaps supplement flight.
MOVEMENT
- Wheels - Although it's not an idea that is completely my own, I feel that I may be one of the first to describe it in detail. Using wheels for locomotion is unheardof in biology, but that doesn't mean it is infeasible. Of course, there are many considerations that need to be made when thinking of an alien with "wheels".
Wheels are designed to make continuous revolutions about some supporting structure, like an axle (in this case, the axle doesn't rotate with the wheel). Because of this, the wheel cannot be directly connected to the axle or any other part of the creature's body, as this would only provided limited revolution or no revolution at all. This is a problem. Blood vessels cannot connect to the wheel in a conventional sense and would therefore be unable to provide it with nourishment. This problem might possibly be overcome if there is some indirect blood supply.
For instance, let's say that the blood vessels near the wheel dump their supply into some kind of holding chamber between the static supporting structure (like the axle) and the rotating wheel. Here, the chamber is composed of two hemispherical parts, one inside the other, where one side is imbeded in the static flesh and the other in the wheel. The wheel half can rotate inside the axle half and forms a tight seal between them, thus allowing blood to travel from the rest of the organism to the wheel without direct connections. This would allow the wheel to grow and regenerate worn-down skin on the wheel's exterior.
This also has a problem though. If there is blood in the wheel, then centrifugal force from the rotation of the wheel will cause the blood to concentrate itself just under the wheel's surface. This would cause the inner portion of the wheel to become blood deficient, and may cause it to die. An organism like this may only be able to move for limited periods of time, afterwhich it must rest to allow recirculation of blood.
A possible way to avoid this is by having wheels composed of tough, dead tissue or proteins similar to keratin. Since the wheel no longer needs a blood supply, it doesn't have circulation issues. This also allows it to be completely detatched from surrounding limbs and tissue. You might imagine an organism that has an axle-like extension that it grows the wheel on, much like we grow fingernails. The proteins eventually grow out from it to produce a thick, tough, wheel-like structure. After completing the growth, the connections between the axle and the wheel are broken by using enzymes. Now the wheel is free to rotate about the creature's axle. Of course, the ends of the axle would be blocked so that the wheel would not slip off the axle while it spins.
Of course, wheels wear down over time, and a dead wheel could not repair this damage. Perhaps the organism's wheels would be designed to last only until it reached sexual maturity, at which point it could reproduce and thus become expendible. It shouldn't be too difficult to make the wheels out of some material that would last that long, depending on the creature's top speed and the terrain it covered. Imagine wheels made of a turtle shell-like material, for example.
Now that at least two wheel-types have been designed, the issue of propulsion is at hand. Wheels alone cannot move an organism. One possible method of movement would be to use a foot-like limb to continuousy spin the wheel about the axle. In the case of a living wheel, there may be structures that spin the wheel from the inside, by gripping some internal part of the wheel and pushing against it each time it made a revolution. Either of these methods would likely result in a creature that isn't too fast, perhaps going 30 mph at best in Earth's gravity. In other environments, their speed may be much greater.
REPRODUCTION
- Liquid Fruits - By botanical definition, a fruit is the ripened ovary of a seed plant with various accesory parts that may surround that ovary. Although there would be no true plants on alien worlds (as explained earlier), we can imagine that plant-like aliens may indeed produce fruits or fruit-like structures as well. The reason that many fruits are even produced is so they can be eaten by animals, thus allowing the seeds within to pass unharmed through the digestive tract to a new location. We might imagine some alien plantoid as changing this strategy a bit. What if they produced fruits not as a food, but as a drink?
The fruit in this case would be a mixture of some nutritious, pleasant-tasting liquid and seeds. The liquid could be secreted into several cup-like organs that grow out from the plantoid. A thirsty animaloid could use these organs to its advantage, drinking drom them whenever necessary. The seeds (which would presumably be very small) would be taken up with the liquid, and would be dispersed in the usual manner as seen on Earth.
There are certain advantages liquid fruits would have over solid ones. Solid fruits must be formed from the growth of specific tissues into a certain shape and size. With a liquid fruit, the job is easier on the plant because it only needs to secrete a mixture of chemicals into the seed-containing chamber. This requires no new growth of tissue. It would easier for many animaloids to consume liquid fruits than solid ones as well, since no chewing would be required.
Liquid fruits also have disadvantages. Because their nutritious parts are fluid, it allows most any animaloid to consume them, even tiny ones. Very small creatures (like insects), might be able to readily consume the liquid without taking in the seeds. That would add up to a waste on the plantoid's part. This problem might be solved if the plantoid secreted "insecticides" into the liquid. The fruit might also be subject to evaporation, which solid fruits don't experience. In order to avoid this, the plantoid's cup-like organs may close-up when temperatures raise past a certain point.
- Mature Birth - In the vertebrates, we can see an increasing amount of devotion to the survival of individual offspring as we go through classes. With many fish and amphibians, sperm and eggs are released externally to unite and develop in a relatively hostile environment. In reptiles, the survivability of individuals is increased due to the implementation of a hardened shell that surrounds the egg. The same applies to birds, but they tend to go further by protecting and raising their offspring. Placental mammals contribute the most to the survival of their young by growing them within their own bodies, and then by suckling them.
As the parental resources devoted to individual offspring increases, the number of young tends to decrease. Because of this, some mammals can get by even if they raise only 1 offspring every mating season. My proposal is to continue the trend, where a hypothetical alien parent devotes even more resources to a single offspring than mammals do. Imagine a placentally-reproductive alien that keeps a developing fetus within itself until that fetus has reached full maturity. By doing this, the offspring is fully developed and ready to mate as soon as it is born.
Obviously, the mother would need to have a very elastic body to allow for the growth of an organism within herself that equals her own size. This is possible, since the Gulper Eel on Earth is known to eat prey that is even bigger than itself. During pregnancy, the female will no doubt have difficulty avoiding predators, so her mate may well have to feed her and protect her. We might expect the male to be brightly colored to attract the attention of predators, while the female uses camouflage to stay inconspicuous. The male could then lead predators away from the their mate.
They probably would not have notable intelligence, since the offspring would be fully developed at birth and wouldn't have a chance to learn from their parents during the growth phase. Thus, we could expect them to live on instinct alone and be as intelligent as perhaps reptiles.
- Mutagenic Reproduction - It is thought by some that sexual reproduction is beneficial because it allows a population to adapt to change quickly by varying the genetic code. The only way that an asexual line of organisms can do this is through mutation, which tends to be rare and disadvantuous. However, an asexual organism that purposefully produces mutations in its offspring may allow for variation.
The parent organism would secrete mutagenic chemicals into its batch of gametes or zygotes, which would generate changes in their genetic code. The secretion would need to be limited to only short periods, otherwise dangerous mutations could result in the parent organism itself. Of course, many of these mutations would be harmful. This may be offset if the parent produces a very large number of offspring, or if it tests for its offsprings' viability itself. This may work similarly to the womb of a shark, where fetuses often compete and consume one-another. Those fetuses with the best genetic material survive, and those with lethal mutations never see the light of day.
- Virus-like Reproduction - Viruses provide a unique reproductive pathway which might be interesting to see in well-developed, multicellular organisms. Imagine a creature that injects virus-like reproductive particles into a host organism. Whether these particles contain genetic material from that single parent organisms alone, or whether they are the product of mating, is optional.
These particles seek out specific cells in the host, and then inject their genetic code into them. However, the injected genetic code does not provoke the cells to produce more virus-like particles. Instead, the host cells are stimulated to become zygotes of the parasite. These zygotes grow parasitically, sapping nutrients from the host organism until they reach maturity and burrow out through its skin, perhaps even killing the host. This is reminiscent of the bot fly life cycle. Suppresion of the host's immune system may be necessary to ensure survival of the zygotes, perhaps through the use of some chemical.