My wife and I were talking about sensory organs and what they might be like on animals on other planets. And of course I carried it way to far for my wife to stay interested so I’ll write about it here.

Lets start with the obvious senses that we have. I’m not so much interested in the sensory organs that we have but more what physical attributes can be sensed.

Electromagnetic/vision : sensing the energy contained in photons. This is different than feeling, say the heat from a fireplace. In that case the photons heat the surface of the skin and that in turn is picked up by specialized nerves.

Vibratory : This is our sense of detecting the pressure waves in the air - hearing. Other animals, for instance dolphins, detect pressure waves in water. And snakes detect vibrations in the ground. Though I’m not sure that sense is different than our ability to detect vibrations in a solid only more refined.

Perhaps the difference is in how the vibrations are registered. Our hearing is registered by tiny bones oscillating. Our feeling of vibrations is picking up changes in acceleration.

Molecular analysis : ( not a very good name but the first that comes to mind. ) This is smelling and tasting. Molecules are binding with other molecules in our sensory organs and based on the number of specific bindings produce a sensory input.

Somatosensory : the combination of nerve endings that detect pressure, temperature, heat, etc.

That covers our basic five. What others are there?

Magnetic : Humans probably don’t sense this but migratory birds do.

Electric : I’m not sure if there are any organisms on earth that detect electric currents. Eels produce an electric current so perhaps they have some sort of way of communicating with other eels in this fashion.

It isn’t hard to imagine that there could be environments somewhere in the universe where the ability to sense electric fields might come in handy.

Gravitational : Okay, you could say that we all sense gravity. But that’s probably under the the sense of touch for us. What about organisms that might sense changes in gravitational fields? This might come in handy for an organism in a system with lots of moons. The environment might change due to alignments of the moons/planet so that under certain conditions the organism might need to migrate to another location for food or safety.

Radioactive decay : If an organism had the ability to detect the Weak force it would show up as high energy photons. Imagine an environment where there are areas with lots of radioactive decay and other areas where there is very little. There might be an organism that could detect these photons so that it could avoid the highly radioactive areas.

Note: I’m not sure if this should be considered different than the electromagnetic/vision sense. My first impression is that it should because while it is ultimately sensing photons they are produced by very different means and mean very different things to the organism.

Strong force : This is a real long shot. The strong force isn’t directly detectable outside of the nucleus of an atom. The only environment I could image where an organism might be able to detect the strong force is if there is some form of life on a neutron star.

Any such life would be non biologic since no molecule can exist on a neutron star. But there might be some combination of particles that can exist on/in a neutron star that could maintain a pattern. It’s a real stretch but as is said, “life finds a way.” In this instance we may never know because it may be beyond any technology to ever detect that level of detail on a neutron star. Perhaps someday computer simulations might shed some light on this far out possibility.

Radio : This again is the electromagnetic sense but perhaps like detecting radioactive decay this one deserves it’s own category. I’m thinking about the hypothesized giant gas bags dreamed up in Arthur Clarke’s novels. I would suppose these GGBs can sense radio waves from lightning because they might be attracted to them for energy/nutrients or repelled from them because of the obvious danger. Perhaps more likely they would be attracted to the wake of a lightning storm where there might be specific nutrients that they desire.

Can you think of any other forms of physical perception?