When just a dozen of them remained alive, feeding on aquatic organism, doing things which were almost impossible, but still for their survival they did.
They then started swimming on hourly basis evy day, then would spend 12 hours resting and 12 hour swimming in the conquest of food. They didn't give damn to their degenrating hands and feets or their almost disappearing lungs and oxygen system.
Firstly, they could get in water for just minutes. Then slowly it turned to hour, then hour turned into hours and then slowly slowly their body undergoes mutation, giving them tail in place of feet and their phalanges of hands grow further to help them in holding things easily in their hands.
