When we think of life on other worlds, we seem to think most often about sentient life. We think about the space-faring Greys, or maybe humanoid types whom we will meet.

But what about the other creatures?

Since I was a geek for nature documentaries and books form an early age, I studied animals and their ecosystems at great length.

So if we locate a planet with life, what can we expect to find?

Extremiphiles seem likely. Given what we've seen in the harsh environments on Earth, it seems that there could well be organisms living in extreme environments elsewhere.

In every ecosystem, and in many different environments, we find an array of niches that animals fill.

We find carnivores, herbivores, omnivores, and scavengers.

Where you grazing buffalo or antelope, there are lions or wolves to prey upon them. There are generally vultures to clean up the mess.

The same thing goes for aquatic life. Sharks and killer whales feed on fish and mammals. Crabs, worms, and hag fish, in turn, gobble up the leftovers.

So, we can expect to find ecosystems where there are predators and prey, and scavengers to take care of the garbage left behind.

Imagine if you will, a planet covered in dense clouds and heavily-laden with methane. The few solid surfaces are covered in volcanic ash rich with minerals.

Let's call it Avalon.

Land masses are sparse, and are surrounded by seas of liquid methane and ethane. Mats of bacteria carpet large areas of the seas. Within these mats live organisms who use the nooks and crannies on these islands for shelter.

The Frisbee Slug is a disc-shaped grazer that feeds on the mat. A few of these diner-plate-sized critters keep the mats form growing too thick and heavy to stay afloat. If too many Frisbees are present, the mat will fray and disintegrate.

Scarlet Gadflies make their homes in the larger nooks. They prey on the Frisbee Slugs when they reach adulthood. They are pear-shaped, with two pairs of wings and the same number of legs. They descend upon the Frisbees near the time they reach sexual maturity. Predation keeps the Frisbees in check, as well as their prodigious breeding.

Beneath the surface are the Kraits.

The Leopard Kraits is a meter-long beast resembling a centipede. The first three of its 20 pairs of legs are long, powerful, and tipped with bailing hooks for grabbing and piercing prey. The remaining pairs are flattened into fins. It is an opportunistic predator who is content stealing from neighbors when prey is scarce.

Silver Kraits are bottom-feeders. Frequenting the depths, they dive for worms and carrion. They are twice the size of the Leopard Kraits.

King Kraits are thick-bodied, and up to four meters long. Their short, stubby limbs can haul them onto the rocks where they feed on coral-like organisms at the shore. Packs of Leopard Kraits can handle a King. A single Leopard, though, is likely to get gored and stung repeatedly by the King's spiked tail.

Just some vivid imagery from my own imagination....

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"I am Ripper...Tearer...Slasher...Gouger. I am the Teeth in the Darkness, the Talons in the Night. Mine is Strength...and Lust...and Power! I AM BEOWULF!"

The Wildlife of Star Wars addresses this very well. You might want to look the book up.

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I've never once thought of Greys. And humanoids only before I learned how unlikely they were.

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What is the temperature range?

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I never calculated that. However cold is necessary to liquify methane and ethane...IT all just spewed spontaneously from my fertile brain.

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Fallen, but not Forgotten....
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"I am Ripper...Tearer...Slasher...Gouger. I am the Teeth in the Darkness, the Talons in the Night. Mine is Strength...and Lust...and Power! I AM BEOWULF!"

If you haven't seen it already, try the Alien Planet DVD from the Discovery Channel. The production is quite creative and the graphics are excellent. They solicited speculations from scientists (featured in the film) and also had them speculate on what the film makers created. A clever idea in that it forced them to justify in terms of what we know of life on Earth what they were observing on the hypothetical planet, which was often more bizarre than the website lets on.
http://dsc.discovery.com/convergence...et/splash.html

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I would suggest, then, that the temperature would be very low (although we haven't discussed pressure, the pressure would need to be very high to liquify methane at Earth-like temperatures).

I would say that would mean that methane based life would be very slow in metabolism, which would probably rule out powered flight. Gliding would probably be okay, though, and in a dense, Titan-like atmosphere might be very close to swimming.

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I taped Alien Planet (with my coal-fired, steam powered VCR) and still find it fun, interesting, and, most of all, different. Nothing was more than remotely Earthlike, but they all seemed more or less plausible, given the environment presented. Also, I liked it because nothing was humanoid. I am tired of humanoid aliens. I think thay are just creative laziness. Anyway, your planet, Avalon seems downright Titanesque. Very cool.

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I also took a look at Alien Planet after it was mentioned earlier. I found it insufferable! I really hate these type of programs that pretend to be documentaries but are in fact total fantasy. There is something so jarring when you have so called experts in the field talking about the mating habits and feeding behaviours of imaginary cgi creatures. Bleh!

I really enjoyed Alien Planet, moreso than the NGC's more scientifically-rigorous equivalent Extraterrestial. Ironically, I think that's because AP is fundamentally the product of an artist (Wayne Barlowe) rather than a scientist, someone whose concern is "Does it look cool?" rather than "Is it likely?" I never found Darwin IV very likely, but it is very cool.

Just my two bits.

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(Some slight spoilers)
I thought it was fun that they presented the various animated life forms "as is" to actual scientists, that is, presented them as "a given" and from that the guests had to theorize or justify what they saw in terms of real science. In some cases the speculations seemed believable - such as the rapidly running and turning animal being chased by a predator early on. It was speculated that the running creature's single melded front and rear limbs had apparently evolved from what were once four separate legs.

On the other hand, the way-out, weird things such as the gigantic (mile long) walking forest, (on a planet approximately the same size as Earth,) caused one biologist to be concerned about gravity and to say something like "I guess that creature has a much lower molecular mass." The main problem with that enormous animal is that it had a gigantic mouth. What does it eat?

Communicating with light or color changes as the Earth probe did with some creatures near the end is not far-fetched, as alien as those life-forms looked. Some squid in Earth's oceans also signal with color pulses.

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"Insignificant molehill sometimes more important than conspicuous mountain." - Charlie Chan

One niche is in the chest of humanoid hosts who land in search of a distress signal.

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