18

Lungs. Crustaceans and arachnids have managed to evolve lungs directly from gills, unlike tetrapods in which the primitive gill structures are homologous to various structural features in tetrapod skulls, and cephalopods could conceivably do the same. The most significant innovation would be a means to keep the mantle chamber housing the gills inflated out ...


12

They are a genetically identical nest, like the social insects. Making war means cooperation, which means putting the needs of the group ahead of the needs of the individual. Humans are able to do that to some degree which accounts for much of our success as a species. The social insects do that better than anything else. The organism is the nest and ...


9

Yes. Rodents are already very close. Depicted: a red squirrel skull. The teeth are far out at the front of the jaw. In some species they protrude right out of the mouth so they can be used (for digging) with the mouth closed. Here is a gopher displaying this source Looking into the future, I foresee protests that these teeth are not curved at the ...


7

Sulfur-based life is pretty unlikely, for the same reason that life on Earth isn't oxygen-based. Sulfur, like oxygen, usually only likes to form two covalent chemical bonds. Thus, you can in principle have chains of sulfur atoms of varying lengths with with different atoms attached to either end, but that really isn't enough variety of structure to permit ...


7

Two-headed creatures - or even humans - are not unknown in reality, and have even been known to survive to adulthood, so as a point mutation it is not beyond the bounds of possibility for it to occur over a very short period relative to the typical evolutionary timescale. In order for this condition to persist across generations, there are several pre-...


7

Let us consider the needs of locomotion in 2, 3 and 4 physical dimensions of a creature with legs walking upon an n-sphere. The simplest situation is a creature in 2 physical dimensions walking upon the edge of a solid disk. Regardless of the number of legs, the greatest efficiency of motion is achieved with 2 or more legs, each leg having a foot joint ...


6

It can be an illusion Many mammals have (the illusion of) glowing yellow eyes - deer, dogs, racoons, etc. I say "illusion" because the eyes themselves are not emitting the light, but reflecting the light. You can think of this something like someone with bleach-white teeth in a dimly-lit room. If the light hits it right, the contrast between that much ...


6

Some fish, such as Betta Splendens (Betta fish), have what are called a Labyrinth organ that allows them to breath air. Its how they survive low oxygen environments when trapped in small, shallow ponds. When oxygen is low, they pop up to the surface and take a breath. Its not a true substitute for lungs (they can't stay out of water forever), but its a ...


5

There's evidence that feathers are an ancestral trait to dinosaurs, and that while people are used to the idea of theropods being feathered, they might have been more widespread, with the possibility that some species, especially larger ones, were mostly featherless but might have retained some feathers for display. On a quadruped, the logical place for that ...


4

The great advantage of echolocation is the ability to judge distance. It works the same way sonar works: The bat sounds a chirp, and distance is estimated by the time it takes for the sound from its source, to the object or obstacle and back to the ears of its originator. Sonar echolocation for hunting as well as hearing you way through has advantages over ...


4

Anticipatory TL;DR: In order to have a large flying hexapod, you might want to consider adding: Flaps between limbs A habitat near some form of updraft - ocean winds, volcanic wind, or some manufactured thing. Honeycombed bones; an organ to create hydrogen An incredibly large diet; perhaps hibernation when this isn't possible Dense atmospheres Depending ...


4

Two thoughts: First, there's no particular reason that the brain needs to be located in the head. Such a creature could have a single brain located in the body cavity, in which case the 'heads' would be little more than sensory extensions, allowing it to see, speak, and smell in different directions simultaneously. The heads would appear to act ...


4

Is yellow bioluminescence a thing? Yeah, look at Firefly How do the eyes work without pupils? It does not, without hole in iris no light would came to eye. In case you meant absence of iris, it can work, but you lose ability to accommodate to different light insensitivity, situation when someone don't have it is called Anidrida, look it up. Doesn't the ...


4

Handwaving away some of the problems here, one basic one appears insurmountable: Decoherence. This is a process that involves the destruction of the superposition of a quantum system. The loss of quantum coherence is a major experimental problem in, among other things, quantum computing. Minute interactions with the outside environment - heat, light, ...


4

If we want it to be realistic, there is no way. This is result of few factors: The solar radiation on the earth in the upper atmosphere (before it is reduced by atmospheric effects and clouds) is 1300 W/m^2. Human body surface is 1.9 m^2, and at least 1/2 of it will be facing away from the sun. Then following that the shape of your body will reduce the ...


4

You basically just described the last common ancestor of reptiles and amphibians so yeah, absolutely possible. The only issue is that this would be an absolutely ancient species, or a living fossil type situation.


4

What you're describing is (on balance of probabilities) Chromium Based Life. First of all we need to address what we mean when we say 'X-based life'. Carbon based life for instance means that the organic compounds on which that life is based relies on Carbon as a 'binding agent' (simplification but functionally correct). That is to say, Carbon forms the ...


3

An option that others have not mentioned... Consider a creature whose vision works well down in the infrared (effectively 'seeing' heat), or well up into the ultraviolet (the way some insect eyes do). In that case, a yellow glow would not interfere with its vision, because yellow is out of its visual range, and pupils might not be recognizable as such ...


3

One possibility is has been answered already, for various reasons related to evolution in a low light environment. Another possibility is similar to an astronaut's visor: The eyes may have evolved a reflective sheen to reduce the incoming light. Ideally this would adjust for lighting conditions the same way the iris would contract or expand. In this ...


3

Clearly you're talking about a photosynthetic organism, albeit one with very precise responses to different wavelengths. My suggestion would be a creature that evolved on a planet orbiting a ternary star system, where the wavelength of sunlight changes dramatically in a cycle with a period of months of years, and which has evolved such that this cycle ...


3

To calculate it, you need to choose a wing-loading factor: Wing loading for birds is generally between 1 to 20 kg/m2. The maximum possible wing load before a bird is unable to fly is about 25 kg/m2. This is when the bird is too heavy for its wings (like the kiwi, which has tiny wings and a large body mass). So 1638 lbs is c.a. 743kg. That means: with a ...


3

There is a balance between the length of the limb and the amount of force it can apply to draw the string. Longer than a certain point and the amount of force the limb can produce declines, shorter than a certain point and the length of the draw, and hence the time available to accelerate the arrow, will decline. So probably what you want is a little less ...


3

I'm going to assume you want the classical "brute extremely dangerous fighter culture in space" type of warrior, if not then Willk's answer should be it. While strength is often prized, strength will not win you a space battle with guns. An intelligent silverback gorilla would carry a big gun and take a lot of firepower to take down but he would also ...


3

For a race of galactic conquerors, biological traits would be secondary to social and psychological ones. The species may be small and weak, but they should value cooperation, possess an expansionist's mindset and feel no mercy towards other sentinels. Physical weakness can be complemented by technology. The lack of bravery and determination can not be. ...


3

Predator features here on earth include: - Eyes on the front of the head: binocular vision helps tracks prey - Claws, Fangs and sharp teeth for eating meat - Fast reflexes - Lean build - tails are possible, they help with balancing during high-speed chases Senses like smell or eyesights are equally important for predator and prey, so I would not expect ...


2

You might want to first ask yourself where the fungus would be hosted. Each of your organs offer very different environments in which a micro-organism can live. The additional functions granted by the fungus would then depend on which organs are affected: Skin: By forming a thick coating on the host's skin, the fungus would serve as a protection against ...


2

Even if the feathers may not solve a physical purpose, There could be some reasons for their existence like: Mating A peacock has those bright beautiful feathers as a tail, they don't serve much of a purpose other than the real purpose, that is attracting a female. Almost all birds use their feathers to attract a potential mate. Your creature may use these ...


2

Birds developed beaks in order to lighten their structural mass as part of the evolutionary adaptations for flight. The beak replaces the canines in terms of being able to cut through meat (or seeds) in order to get at the nutritious interior, while the grinding molar function has been taken over by a muscular crop in the digestive system (often filled with ...


2

Its not unplausable, however there needs to be a reason for the creature not flying again. Animals are very much living creatures, and all things equal - being alive tops being dead. Also if these creatures have general intelligence there will be a learning period, this is often provided for by the parent/herd/pack. In the absence of the mother these ...


2

Taxonomically speaking, the class of a living entity is usually determined by a common mode of reproduction. The class Reptilia is different from the class Mamalia and different from the class Amphibia primarily because amphibians (usually) deposit gel-encased eggs in bodies of water, reptiles (usually) produce leathery eggs that they bury, and mammals (...


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