What Do Animals Think Of?

There was this episode in Friends where everyone's thoughts are narrated out loud. The six of them are in their cafe and Ross is talking about one of his many dinosaur stories, and the others are sitting there listening to him. Or at least they pretend to. Now that their thoughts are being narrated out loud, here's what they're all actually doing.

Rachel : *squints eyes* I love how he cares so much about stuff. If I squint, I can pretend he's Alan Alda.

Monica : *Giving him the Pan Am Smile* Oh good, another dinosaur story. When are those gonna become extinct?

Chandler : *nods his head as if he was understanding every bit of it* If I was a superhero, who could fly and be invisible, that would be the best!

Gunther : *serves coffee* What does Rachel see in this guy? I love Rachel. I wish she was my wife.

Joey : Hums a song in his mind. Taa da taaa ta duu.

Phoebe : Hey, who's singing?

The 6 of them are all sitting within a 10 meter radius, and yet they're all in completely different worlds. In Joey's mind, he's probably a sandwich shop owner somewhere, Chandler is a Flash/Superman hybrid in his own world, this is Phoebe in her mind, and Rachel is probably dating Justin Theroux in her world. Oh wait. ;) 

Each individual thinks. Even though Joey is portrayed as the dumbest of the lot, he still thinks. And so is the case with every human soul.

Now look at this.

6 camels. The third one from the left, zoned out in his own world looks most like Joey!

What are these creatures doing apart from the time they spend eating, sleeping, and drinking water? Those that are not enslaved by humans have absolutely no job at all! All those animals in the Amazon, away from humanity, live their lives hunting or being hunted. But in all that mean time, what are they doing?

Does a zebra think of how it'd be like to fly like a Pigeon? 
Or does a crocodile think of what its life would be like if he was less lazy? 
Wait, does he know what being lazy is?

I've been researching on this for some time now, and honestly find it very difficult to comprehend the fact that we are still unable to communicate with animals. Though I understand animals have a limited set of emotions, and hence less signals for each one, they still manage to communicate to their own species that danger is arriving when it does. An elephant knows exactly how to 'act sexy' to find a mate. (The male elephant attracts its mate by continuously dripping a trail of strong smelling urine. It also makes mating calls, which attracts females.) Though primitive, animals do communicate amongst themselves.
Take your pet labrador for example. You know when it is excited and in the mood to go outside for a run. The lab also knows when you are upset, and cuddles up to you. On returning from a vacation, there is no human alive that missed you as much as the lab. (Do watch this).
We have established that animals do have feelings, and that they communicate with each other through simple signals, sounds, or calls. But, do they have a complete language that forms structured sentences? Or is their vocab limited to
"Run!" 
"Danger." 
"Love." 
"Oh, sexy"
Maybe so. Coming back to questioning an animal's ability to think, I believe it is the lack of a complete language that animals do not think. A dog may understand his owner is upset, and that is as far as his ability to think/understand goes, as I am certain it never questions itself,
"Why is he upset?"

So, if you can't speak, are your thoughts just limited to emotions, and your present state of being? -Happy, excited, upset, lazy?
I don't buy that. To make this more relatable, let's talk about a deaf and dumb person. One who has never heard a word in his entire life, nor has spoken one. Does he think? We're certain he has feelings. And that throughout the day there are instances that make him feel one of the many emotions a human portrays. But during all those voids where there is no prevalent feeling/emotion, what does he do? Compare this exact thought to this animal. There are flashes of great emotions, but when there is nothing to do, does he think?

Again. Is the ability to think limited to the ability to speak? If so, do we think in a specific language? 
I am not sure of whether I've ever thought without a language. Conscious thoughts are all in the language you choose to think in. Unconscious thoughts, for example reactions, or immediate responses to an event, are generally in your mother tongue (remember the tale where Birbal determines a multilingual man's mother tongue by throwing cold water on him during the middle of the night?)

I've left several questions unanswered. Almost all, in fact. If it all I ever get into the field of research, animals and communication will be the topic of my first research.