Imagining Alien Lifeforms (part 2)

I've always been interested in biology, so designing aliens is very exciting to me. When the intelligent alien races of Solar Echoes were developed, one of the main questions I asked was: what are some of the most resilient creatures on earth that would be likely to survive a variety of environments on different worlds? For example, insects are an obvious choice, so the Chiraktis seemed a logical and believable type of alien race that might exist on other planets. I asked myself the same question when designing alien lifeforms, but it was broader—these creatures didn't have to be intelligent or have any form of civilization, and they might only be indigenous to their own respective planets. Often, I imagined lifeforms based on their environments rather than design them and then try to explain why they made any sense biologically. For example, I thought about an ice-covered planet like Jupiter's moon, Europa. What might live there, and how would it adapt to living there? I designed a creature that had grown its hoof-like toe-nails into blades for skating upon the ice while using a membrane stretched between a two-pronged tail to catch the wind like a sail, propelling it at high speeds over the planet's icy surface. This lifeform was designed while considering how it would adapt to and survive in a specific environment.