"After it was swept and lost its mother, the hippo was traumatized. It had to look for something to be a surrogate mother. Fortunately, it landed on the tortoise and established a strong bond. They swim, eat and sleep together," the ecologist added. "The hippo follows the tortoise exactly the way it follows its mother. If somebody approaches the tortoise, the hippo becomes aggressive, as if protecting its biological mother," Kahumbu added.

"The hippo is a young baby, he was left at a very tender age and by nature, hippos are social animals that like to stay with their mothers for four years," he explained.