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Discontent -

This lion looks like he's received some bad news. (Photo by Lemuel Butler)

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Screeching - A rare Pallas's cat reacts to being threatened. (Photo: Flickr/CC BY-ND 2.0)

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Possesive - A seagull being very protective of its wall. (Photo: Flickr/CC BY-NC-ND 2.0)

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Scolded - This tiger is getting a real telling off from its partner. (Photo: Flickr/CC BY-ND 2.0)

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Furious - This ant obviously doesn't like being photographed. (Photo: Flickr/CC BY-NC-ND 2.0)

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Dissatisfied - This bird has an attitude problem. (Photo: Flickr/CC BY 2.0)

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Chided - An adult seal has a sharp word with junior. (Photo: Flickr/CC BY-NC-ND 2.0)

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Scornful - An indignant look says everything about this terse chicken. (Photo: Flickr/CC BY-NC-ND 2.0)

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Hot-headed - A far from happy brown bear snarls its displeasure. (Photo: Flickr/CC BY-NC 2.0-cropped and enlarged)

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Provoked - Penguins arguing with each other. (Photo: Flickr/CC BY-NC-ND 2.0)

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Bitter - This bird is blue in the face. (Photo: Flickr/CC BY 2.0)

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Offended - If looks could kill... this marmoset is left speechless. (Photo: Flickr/CC BY-ND 2.0)

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Riled - Ears back and hissing, this serval is ready for a fight. (Photo: Flickr/CC BY-ND 2.0)

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Sulky - A robin standing in the snow, sulking. (Photo: Flickr/CC BY 2.0)

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Vexed - This fish is wondering what all the fuss is about. (Photo: Flickr/CC BY 2.0)

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Aggravated - Ready to strike! This duck in full battle mode. (Photo: Flickr/CC BY 2.0)

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Mean - You don't want to mess with this emu, who's clearly looking for trouble. (Photo: Flickr/CC BY-NC-ND 2.0)

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Displeased - Woken from its slumber, a cow gets ready to lock horns. (Photo: Flickr/CC BY 2.0)

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Provoked - This pelican is letting his opinion be known. (Photo: Flickr/CC BY-NC 2.0)

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Troublesome - An ill-tempered hawk has no time for photos. (Photo: Flickr/CC BY-NC-ND 2.0)

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Agitated - Even a goose can get down and dirty when it wants to.

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Irate - This snake is slender, smooth, and sinister.

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Incensed - Here's the business end of an angry eel.

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Poker-faced - The day just doesn't seem to be going right for this fed up chimpanzee.

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Upset -

If you upset a hippo, they'll send in the heavy mob. 

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Misbehaving - This cat is throwing a temper tantrum.

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Disgruntled - Sometimes even a muscular, hefty English  bulldog doesn't like getting its paws wet.

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Furious - You simply don't argue with an enraged bald eagle. Period! (Photo by Patrick Brinksma)

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Bothered - You got something to say? This buffalo is in no mood for chit-chat.

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Piqued - This tiny hummingbird looks lost in thought.

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Bedraggled - This is what happens when a praying mantis forgets its umbrella.

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Grumpy - Where's my dinner? A hungry toad is not a happy toad. (Photo: Flickr/CC BY-NC 2.0)

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Fed up - Winter blues appears to have caught up with this snow-bound hound. (Photo: Flickr/CC BY 2.0)

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Uncomfortable - Ever wondered what a rhinoceros chewing a wasp looks like? (Photo: Flickr/CC BY-NC 2.0)

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Dispirited - Getting old is no fun at all. (Photo: Flickr/CC BY-SA 2.0-enlarged)

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Argumentative - This fluffy bird is preaching to the converted. (Photo: Flickr/CC BY 2.0)

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Impatient - Clearly grumpy, this gorilla is fed up waiting for something to happen. (Photo: Flickr/CC BY-SA 2.0)

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Miffed - I mean, did I ask for a shower? A picture that speaks volumes as to why cats don't like water.

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Lonely - This monkey looks like it's in a reflective mood. (Photo: Flickr/CC BY 2.0)

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Bewildered - For this goldfish, seeing is believing!

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Morose - Has this monkey received some bad news or what?

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Dejected - Soaked through, this pony could probably use a towel and comb.

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Worried - Looks like this pug is waiting for its exam results. (Photo: Avigyan Chatterjee)

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Harassed - It's a really bad hair day for this alpaca.

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Exasperated - A vocal zebra voices its displeasure.

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Mouthy - Too much gossip for one snow leopard whose partner just won't shut up. (Photo: Flickr/CC BY-ND 2.0)

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Fearsome - Fluffy but fierce, this feline likes its own space. (Photo: Flickr/CC BY-NC 2.0)

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Defiant - An iguana guarding its territory. (Photo: Flickr/CC BY-NC 2.0)

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Troublesome - This little guy is probably growling, "Get your own cave!" (Photo: Flickr/CC BY-NC 2.0)

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Outraged - An attacking swan doing its torpedo impression.

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Preoccupied - This young polar bear seems to have a lot on its mind.

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Marauding - Fancy an argument with this fuming mountain lion? Thought not.

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Overzealous - An otter proudly shows off its new dentures. (Photo: Jason Hafso)

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