Senses

I grew up learning that we humans possessed five senses. Can you quickly name them?

touch

taste

smell

sound

sight

What is a sense? My handy dictionary says, among others,

"a specialized animal function or mechanism (as sight, hearing, smell, taste, or touch) basically involving a stimulus and a sense organ."

I just finished What If the Earth Had Two Moons? by Neil Comins, and he posits an interesting wrinkle to our understanding of senses. Comins writes that two other senses are usually left off the list taught to children, and they are "heat and gravity."

We can put our hand near a fire and feel the heat, but are we using the same sense organs (nerves) we use for touch? Does that make "feeling heat" a part of the sense of touch?

And what sense organs do we use for gravity? To sense when we are falling, do we use another sense organ other than our eyes (seeing the environment pass by) and nerves (feeling the wind, friction and impact)?

What do you think? Seven senses? Or five?