The survival and number of your species does not depend at all on radio waves and whatever they're up to. Not at all! (at least not Earth)

And so all animals are blind and mute.

But it seems like it wouldn't have been hard if there had been a motivating factor.

> be greentext

Imagine another planet with lots of life but eternal clouds so dense visible light has no chance of getting through in useful quantities and/or with any information intact. Let's invent whatever gasses the atmosphere needs to absorb everything up to near microwaves. In any case, suppose the only source of "light" or "electro-magnetic waves" is something in the sky that emits radio. Some point. It could be just constant, giving maybe navigation capabilities when combined with gravity and "down-ness".

An organ to sense the direction of that thing could totally form. It would be pretty crazy. I can imagine some neat ideas. Maybe isolated charges in some blubbery organ. And "nerves" to communicate an "event" to some thing that has a sense of time...maybe it writes out a chained molecule, with a "tagging" molecule whenever an event is received: the rate of the lengthening chain is roughly constant under constant conditions. Like a seismometer protein.

Suppose, all in one specialized fat cell:

1. Cell is "charged" somehow, but can jiggle as it is in some fat.
2. Protien in same cell churns out this seismometer tape molecule.
3. Seismotape has timestamps.
4. Seismotape has an identifier on it too: approximate physical location of cell (x,y,z).
5. There is an organ within this organ that "reads" all of the seismotape. It tries to piece all this together to reconstruct the way a wave could propagate though ..."us" and produce this combination of EM tics. On the tic, er, tape.

Ergo direction of source, or at least axis.

[Update: hmm... electric eels...]