Terrian (Battle for Terra)

Terrians are a sapient alien species and the native inhabitants of a ringed planet that has been christened Terra by Humans.

Biology
Terrians are slim, mermaid-like creatures with a humanoid body and no legs, which swim through their planet's atmosphere by vertical undulation. They have pale hairless skin, thin necks and round heads, with a single crest-like tentacle growing from the back of their heads. Their eyes are large, and their nostrils are located on a high point between the eyes. Their arms terminate on tridactyl hands with flat broad fingers.

How the Terrians remain airborne is not clear, since the gravity and atmospheric density of Terra doesn't seem to differ significantly from Earth's, given how Humans move around normally while on the planet. It's thus possible that the Terrians might have internal bladders filled with lighter-than-air gases, to allow them to fly without wings.

The Terrian atmosphere is mostly devoid of oxygen, which is only produced by a few species of Terrian vegetation. The oxygen level is so low that a Human cannot survive for more than 27 seconds in Terra's atmosphere. Likewise, Earth-like levels of oxygen are lethal for Terrians.

Culture and society
In the past, Terrians were a warlike species, which almost resulted in their extinction. The survivors recreated their society as a peaceful one, with emphasis on artistic endeavors, low-level technology, and keeping in tune with nature. Their advanced technology wasn't destroyed, however, but preserved to be used to defend themselves in case of emergency, which proved useful when their world was invaded by Humans.

Modern Terrians build their settlements within the trunks of humongous tree-like life forms which grow amidst the clouds and mountainous outcrops of their homeworld. Their religion is polytheistic and they're ruled by a Council of Elders.

Appearances

 * Battle for Terra (2007)