Being able to recognize ones self in a mirror ( which a dolphin supposedly can) is much different that being sentient or "self aware".
@Bhs and @Hannibal
How would you guys define "sentient" and "consciousness"?
IF all our thoughts etc. were created in our brain by neural cells - would consciousness be possible?
Sentience is the ability to feel, perceive, and to have subjective experiences. > Awareness is then developed - sense data can be confirmed by a being without necessarily implying understanding. > Consciousness – an ignited, robust, internally stable awareness of one's own sense of values derived through abstract thought processes that are capable of adapting to and integrating with functionally similar processes in a wider range.
Reaching that level of awareness, one have become a creator of his own consciousness – you are no longer just a sentient being – you have evolved to have become a conscious being; capable of processing your experiences and not being subjective to it.
Instincts are God given abilities to all sentient beings to give them awareness, while consciousness is our acceptance and appreciation to what God has given us of abilities and values!
How do you know that other animals aren't conscious? Remember Koko? The gorilla that was taught how to speak sign language, not just copy hand movements, but actually learn the language and use it. She knows up to 1000 words and can speak at the level of a 3 year old child. She can process her surrounding and make decisions on what she wants to say to her caregivers. Her first sign she used was "queen" because she knew that she was getting more special attention than any of the other gorillas. She even became sad when she was told of Robin William's death, as she remembered the time they had met.
https://www.theatlantic.com/technology/archive/2015/08/koko-the-talking-gorilla-sign-language-francine-patterson/402307/
http://www.dailymail.co.uk/news/article-2723584/She-extremely-sad-Sign-language-gorilla-Koko-close-tears-following-news-Robin-Williams-death-13-years-video-captured-two-fast-friends.html
(Sorry for only giving two sources, I'm sure if you care you can find many more examples)
Oh, I've seen many intelligent creatures in aqua park - they even taught them to kiss you on the cheek!

But, what does that have to do with consciousness?
The "Animal Consciousness" debate has been going on for ever, and different scientists have different opinions on the subject!
A New York University neuro-scientist Joe LeDoux, one of the most vocal of a group of researchers who think non-human animal consciousness isn’t relevant in experiments or even scientifically resolvable, once said, “The basic idea is about how many assumptions scientists are willing to make about consciousness.”
To dive in a deep field where famous scientists and philosophers have failed to conclude, is like blowing in a hollow object!
The way I see it, though;-
Animals are subjective to their instincts, and follow a law that secures their needs.
Humans can evolve and develop a conscious that can free them from being subjective to their instincts, and become in control of their needs, feelings and behavior.
When a man doesn't have control over his sexual and feeding activities > they say he's an animal or eats like a pig!
When a person doesn't have control over his life; he lives in chaos, which leads to destruction. - How can you develop a consciousness in a chaotic state of awareness?
Consciousness is the highest state of awareness and without consciousness we'd go back to the jungle and live with the animals by our instincts and by the jungle law!