You'd have to see it to believe it.
A kitten and a crow. A primate and a pup. Even a predator and its prey.
Defying the laws of nature itself, animal odd couples forge friendships under the most peculiar circumstances. But in the process, they show us that humans aren't the only members of the animal kingdom to demonstrate complex emotions and traits.
"To know that these animals are capable of emotions like love and understanding and caring, like we are, is quite an eye-opener," Tony Fitzjohn, a conservationist with Wildlife Now, says on a National Geographic program airing Saturday.
"Unlikely Animal Friends" features six of the most curious couples the animal kingdom has ever seen. Here are a few of our favorites.
One was an outgoing orangutan, the other an underfed stray dog.
But since the moment they met, Suryia and Roscoe have been inseparable.
Bhagavan "Doc" Antle, founder of The Institute of Greatly Endangered and Rare Species (TIGERS) in Myrtle Beach, S.C., said Roscoe, a Bluetick Coonhound, followed him and Suryia, one of TIGERS' orangutans, through the park's gate one day in 2006.
As soon as Suryia saw Roscoe, he ran over to him and started playing, Antle said. After a few unsuccessful phone calls to find an owner, Antle decided to let Roscoe stay.
Now, the pair has a ball frolicking around the park. For a few hours each day, they swim or roll around in the grass. Suryia will even grab Roscoe's leash and take him for walks around the enclosure, Antle said.
"To me, they seem like long-lost friends. They would make you believe in reincarnation," he said.
After a tsunami washed away his herd and stranded him, a young hippo found himself a most unusual ally: a 130-year-old tortoise.
The 2004 tsunami that devastated Indonesia also hit the eastern shores of Kenya. And after the storm left Owen, a small hippo, all alone, conservationists found a home for him in Haller Park, an animal sanctuary in Mombasa, Kenya.
They hoped that he could be a companion for a female hippo whose previous companion had died. But before they could introduce him to the other adult hippos (which can be aggressive and territorial), they wanted to give him a quiet place of his own to adjust.
And it was there that he met his buddy Mzee, an Aldabra giant tortoise whose name means "old man" in Swahili.
"He ran straight for the tortoise," said Sabine Baer, of Lafarge Eco Systems, which manages Haller Park. "The color is somehow similar like a hippo color. It was somehow round-shaped, so he must have associated it with an adult hippo and with his mother and his family."
At first, it was Owen who made the friendly overtures. But after a while, Mzee appeared to warm up to the heavyset hippo.
They slept together and ate together and even appeared to cuddle together. Owen would nuzzle Mzee's foot when he wanted to eat and Mzee would nibble Owen's tail to steer him.
"[Mzee] taught him to eat the cut leaves, he taught him to eat carrots, so for us, it was an absolute blessing to have that relationship to help us raise Owen," said Baer.
But though the pair became even closer and quite famous, inspiring a Web site and children's books, Baer and others worried that as Owen grew, he would put his smaller friend at risk.
So they decided it was time to move Owen into an enclosure with Cleo, the female hippo who had been waiting for him.
At first, the two eyed each other with suspicion. But it wasn't long before it seemed as though Cleo slowly replaced Mzee in Owen's heart. And, occupied with a new tortoise companion of his own, Mzee didn't seem to mind at all.
"They became inseparable like Owen used to be with Mzee, and now they are together, living together happily ever after," said Baer.
Christian was just a 30-pound cub when Ace Bourke and John Rendall found him in a cage at Harrod's department store in London.
But since that moment in 1969, Christian the lion has become a media sensation, capturing the imagination of people all over the world with his story of unlikely love.
Although he made for a peculiar pet, Bourke and Rendall brought him home and cared for him until he grew to a strapping 130 pounds. They kept him in their furniture store and bonded with him as they would a more traditional house pet.
"They just loved each other," said Wildlife Now's Fitzjohn. "Christian adored them. Ace and John basically were surrogate parents to Christian. They fed him and groomed him and made sure he was safe, and didn't get in trouble, and just wanted the best for him in life."
But as Christian grew, the friends knew that their urban accommodations would soon become an insufficient home.
So, with the help of actor Bill Travers, they contacted George Adamson, a conservationist in Kenya, who agreed to reintroduce Christian to his natural habitat.
Bourke and Rendall flew with Christian to the Kora National Reserve in Kenya. When it was clear that Christian would blend with the lions already there, the friends said their goodbyes.
Although the transition was difficult, Christian eventually lived and thrived with a group of lionesses in the wild.
But his first owners missed him terribly and one year later returned to Kenya. They didn't know what to expect or if Christian would remember them. But the lion's greeting said it all.
Immediately, the 300-pound creature raced to the pair and leapt up to embrace them.
"Once they've given you that trust and their affection, they don't forget who you are and what your relationship was any more than a kid forgets who his mother is, however long," Fitzjohn said.
In one of the most extreme examples of odd animal pairings, a lioness in Kenya adopted a baby antelope in 2001.
Conservationists were dumbfounded as to why the lion, a top African predator, would care for its own prey.
"I couldn't believe my ears when I first heard about the adoption. I just thought that's absolute nonsense. Give it a few hours and that lioness will definitely eat the calf," said Saba Douglas-Hamilton, a conservationist with Nairobi, Kenya-based Save the Elephants.
The lioness was dubbed Kamuniak, which means "blessed one" in the local Samburu language. She wouldn't let the young oryx out of her sight.
"It was very moving to watch," said Douglas-Hamilton. But the situation was deadly for both. Caught at opposite ends of the food chain, neither would eat while they were together. The lion wouldn't hunt and the young calf had no way to get milk.
Douglas-Hamilton said she and others thought the lion had experienced some sort of trauma that "clicked a switch" in her brain, and caused her to see "baby" instead of "food" when she looked at the oryx.
For weeks, the pair traveled the wilderness together. But the relationship was not meant to last. One day while drinking by the river, Kamuniak let the oryx out of her sight for a few seconds – and another lion leapt out of the bushes and attacked the baby.
"[Kamuniak] was clearly terrified of the male lion but she acted exactly like a mother losing her cub, she couldn't leave the scene," said Douglas-Hamilton. But the very next day the lioness went out and killed an impala and fed herself.
She went on to adopt five more oryx calves, though none of the relationships lasted as long as the first, she said.
"It was really charming to see them together. It was like something out of a fairy tale and there was a real sort of intimacy between them. It was really strange. But then again, we develop strong intimate relationships with our pets which are different species," said Douglas-Hamilton. "We do it? Why can't lions?"
If bonds were based on size, these two wouldn't even be acquaintances.
But somehow Bella, a 30-pound dog, and Tara, a 4-ton Asian elephant, have become the best of friends since meeting in 2005.
"They are close. They are always together. They play together, they talk. They sleep, they eat – everything together," said Carol Buckley, founder of The Elephant Sanctuary in Hohenwald, Tennessee.
One day, while exploring property near their sanctuary, Buckley and her partner, Scott Blais, came across a white chow mix that appeared to have a bizarre fascination with big pieces of equipment, such as tractors.
The two brought her home and watched as that attraction extended to the hulking creatures at their park, including one in particular: Tara the elephant.
"Elephants are incredibly careful around their young. Even when they're running and a baby is running around in and around their legs, family members never trip up over a baby. They never nick the baby, they never step on the baby, so I never was concerned for Tara and Bella," said Buckley.
In 2007, when an injury partially paralyzed Bella and forced her indoors, Tara held a vigil outside her window and called to her until caretakers brought her outside. Bella's injury eventually healed and the two now roam the refuge together again.
"It's 24/7. It is a very loving and compassionate relationship they have," said Buckley. "They play together and they never want to be separated."
"Unlikely Animal Friends" will air Saturday, Sept. 26 at 8 p.m. ET on the National Geographic channel. For more information, click here.