The  hippopotamus, nicknamed  Owen  and  weighing about 300 kilograms  (650  pounds), was swept down Sabaki  River into the Indian  Ocean, then forced back to  shore when tsunami waves struck the Kenyan coast on December 26,  before wildlife rangers rescued  him.   "It  is incredible. A-less-than-a-year-old hippo has adopted a male  tortoise, about a  century  old, and the tortoise seems to be very happy with being a  'mother'," ecologist  Paula  Kahumbu,  who  is in charge of Lafarge  Park,  told AFP. 

"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.