Wednesday, June 24, 2009

Today in "Organs I wish I had..."

Despite the fact that his relatives are complete bastards who tunnel through my front lawn and create soft spots that I will inevitably step on sprain my ankle, I am madly in love with this little guy. The fingers! The teeny-tiny eyes! The incredible schnoz! And he lives in wetlands, which I generally don't venture into as I donate more than enough blood to mosquitoes as it is and do enjoy not smelling like a poorly kept men's room, so I can totally get behind his tunnelling to his heart's content there.

But the nose! THE NOSE!! It's the best thing ever. Seriously. Look what it can do underwater:

Don't act like you're not impressed.

Even better than blowing some seriously sweet bubbles though, the nose acts like an eye. It's a bit dark in tunnels, as you will have learned from watching "The Descent", which makes finding food a bit tricky (unless you are a big scary monster with a taste for man-flesh). As you may note, the eyes on these guys are a bit hard to find, and their ears really aren't much better equipped. Sense of smell isn't exactly something to write home about either...but their touch reception on the end of those rays is amazing. Each one of the rays is covered with Eimer's Organs, which are fun little bazoomba-looking nerve endings:

Good stuff. The rays closest to the mouth have the most nerve fibers going to these organs, so these rays are the most sensitive. When I say that the star works like an eye, I really mean it. The moles jam their nose around in their tunnels until it touches something interesting - just like how you would scan bar patrons in search of someone who is not a complete douchebag. Once the prey is located by the peripheral rays, the mole brings the center rays into contact with it to be sure of what it is, or to go back to the bar example, turning your eyes toward the bright red blob in the corner and bringing it into focus (I really don't recommend this, as red blobs almost invariably turn out to be some asshole you met once at a party in college, but I digress).

So, not only do these central rays on the nose act as a kind of tactile fovea for these moles with tons of peripheral nerves supplying it, they also takes up a huge portion of their brain to process the information coming from it. One quarter of the sensory cortex is taken up by just this one ray. To give you some comparison, here is a map of the human sensory cortex where all of the body parts are drawn to scale with amount of representation they have in the brain:

Here's another super-fun representation, just in case you were sleeping too well at night:

Those of you who survived freshman psychology will recognize these as homunculi, which I'm almost positive translates loosely into "Wow, God surely does have a sense of humor to devote so much sensory area to lips and so little to the genitals." Seriously, I was expecting something more like this:

Although something less wrinkly would have appealed to my aesthetic sense a bit more. Also, I can't imagine the data they are losing with this by not including the foreskin...*tsk tsk*

Um, where was I?

Oh yes. Tactile foveation in the star nosed mole. Pretty amazing brain organization for something that most people consider to be quite a simple creature. And...yeah. Mostly I just wanted to post mole pictures. And accompany them with penis pictures. And, well, I have accomplished that, and managed to couch it in something that resembles intelligent discourse. So I win.

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