I can't imagine the increase in cerebral pressure from a 2-ft slug. :p But since you all are so apt to describe Yeerks, I feel I must describe an Andalite. *gang-sign* <Represent!>
First off, imagine a blue centaur. (A centaur is a half-human half-horse crossbreed...I won't go into details about how they look, I assume if you've had any middle-school lit classes you'll know.) Okay...Andalites are generally a little slighter than what a centaur would be... the 'horse' portion of the body is usually closer to the size of a deer's body than a horse's, though with my character Ossanlin, he's a bit on the large side...closer to horse-sized. I digress. Okay, now instead of a little poof-ball tail like a deer or a long fly-flicking tail like a horse, put a long, muscular, fur-covered but snake-like tail on that body, then put a wicked-sharp scythe-shaped blade on the tip of the tail, and you've got a good idea of what the Andalite's lower half looks like. The tail is a nasty natural defense that can be cracked around like a whip with speed, accuracy, and power.
The upper body is humanoid, though the frame and arms especially are generally frail-looking and somewhat weak. Again this is not the case with my character, Ossanlin, who has a developed upper body...but I digress yet again. The main differences from humans on the upper body are 1.) Seven-fingered hands (I'm pretty sure it was seven), 2.) The lack of a nose and mouth, in the place of these features are three vertical slits used for breathing, 3.) fairly large, pointed ears, and 4.) Two prehensile "antennae" on top of the head that each has an eye on the end...called "stalk-eyes". They can be rotated 360 degrees and allow Andalites to have panoramic vision of all of their surroundings.
Most Andalites range from blue to purple and anywhere in between for coloration. The lower body is furred like most cloven animals, but the upper body has only a very fine fur, akin to "peach-fuzz". Eating, drinking, and elimination are accomplished through the hooves. Communication is accomplished through a form of telepathy called "thought-speech". This can be a general speaking tone or even a shout, denoted <like this.> Or it can be directed to one person or a small group akin to a whisper, denoted <<like this.>> The species "hearing" the thought-speech does not need to be telepathic in any way. Most andalites also posess the ability to "morph", or alter their own genetic structure to take on the forms of other living creatures for short periods of time (no longer than 2-hours or there are nasty consequences.) Andalites use more of their brain mass than humans (comparably) and are incredibly intelligent, they also posess more than one heart. I think that covers most generic stuff.
