Jovian (Not Final!)

The Jovians are a sapient, extremely arrogant and xenophobic species from the planet Jupiter.

Biology and Society
Almost nothing is described about the Jovian biology other than noting that they have radial symmetry and are equipped with tentacles. They also possess sense organs directly responsible for detecting mass. Since substances of low specific mass are transparent to them, they are able to see through the dense Jovian atmosphere as well as Humans see through Earth air. Oxygen is lethal to them, and they may also drown if submerged in ammonia, which is known to form lakes in the vast islands where the Jovians build their mostly-underground cities. A very populous planet, even small cities are home to up to ten millions of them.

History
For 25 years they have established radio contact with Human settlers on Ganymede, initially believing the settlers to be creatures similar to them. It is speculated that because of Jupiter's huge size, new civilizations of their own species were still being discovered via radio contact on many points of the planet, hence their natural conclusion that the Ganymedeans would be members of the Jovian race too. As soon as they realize that they're actually dealing with non-Jovians, they immediately cut off all contact, feeling sudden repulsion and hostility towards humanity and the fact that they had been making diplomacy with "lower animals". A trio of sapient robots was later sent down to the planet in hopes of restoring contact and diplomacy with the Jovians.

Technology
Their weapons are mostly based on heat, poison and electricity, since combustibles would be excessively unstable in a hydrogen atmosphere such as Jupiter's and the pressure is high enough to prevent the efficient use of explosives anyway. Furthermore, although their society is very advanced and their technical science at least on pair with that of Humans (as demonstrated by their successful construction of a force field), their astronomy is extremely awkward, as they know about the existence of the sun and the four Galilean moons of Jupiter, but are ignorant over all other celestial bodies (although it's reasonable to suppose that they likely known about Jupiter's lesser moons too but consider them irrelevant, and their definition of "satellites" covers only the four major ones).

Appearances

 * Not Final!, by Isaac Asimov (1941)
 * Victory Unintentional, by Isaac Asimov (1942)