What about Lovecraft's Elder Things? Those had radial symmetry, and they still had perfectly usable graspers/feet/ways of eating and sensing, while also being completely alien. Also, just like in Alien Planet, with the Eosapiens, they could float, thus eliminating the need for legs. You'd only need bipedal movement or bilateral symmetry if the conditions on their planet were similar to those on Earth.

I think life evolved the way it did here because of several sets of circumstances. For one, there was a LUCA (last universal common ancestor) with a few characteristic traits, that all life shares today (i.e. cells). Life on other planets may have a radically different LUCA, that used different methods to achieve the same goals. With different constraints, a different set of results is optimal for natural selection. An example on Earth, even, are molluscs. Cuttlefish and octopi have evolved intelligence near to that of many vertebrates, yet they have extremely different nervous systems. Sentient life would still need to see/think/feel/hear etc., but there are so many ways of doing this, the possibilities are endless.

Something else that makes it even more unlikely that aliens will be similar to us is climate. A slight change in gravity would change everything. If there was low gravity, flight would be more feasible, and maybe sentient flying creatures could evolve (like in Alien Planet). If there was high gravity, things might have pressurized internal cavities and would look more like slugs.

@Fearful_Ferret psychohistory would certainly help, wouldn't it.

Plants still consume and use energy, they just don't physically kill other organisms to do so.



Again a moot point because humans 'hear' due to the way our ears perceive vibrating air and ground particles.



Technically a form of hearing.



Fun fact; when you smell something you're actually breathing in extremely small particles of that substance which your nose all sorts out for your brain, and your nose has thousands of specialized cells which detect the chemicals etc in what you've inhaled to give you a 'smell'. Remind you of another sense? Snakes' "tasting the air" isn't really different from humans "smelling" it.



There's a few other creatures that can do that as well, can't remember many of them though.



Except for superficial differences, the different ways that certain things are done on our planet are remarkably similar if not completely identical. But I do agree with you that in different environments, there would be different ways of life.

The aliens are like, reptiles. But they have a blue tongue. And can flatten out their body. And now comes the best: They're Blue tongue Skinks!

I wasn't saying that everything would be a copy of how things are on earth, I was saying that the same niches will be filled on any planet, regardless of environment, such as a form of mobility, and a dominating intelligent species. I don't see how the ability to fly effects this. I also mentioned somewhere in my bloated post (I commend you if you read it all) that there are alot of possibilites.
Basically what I was trying to do was give some of the necessary traits of any form of life on any planet.

No, it wouldn't, at least in this instance. In case you haven't read Foundation and Earth, I won't say why.

I don't really plan on reading the foundation series any time soon, I don't really like Asimov that much. So please tell me why using psycho-history to predict the most basic and obvious of traits, such as the need to move and the tendency to fill general biological niches is not feasible.

Uh, that plant thing was meant to point out that a living being doesn't necessarily require a mouth to eat.