how did the sea creature go about defying instinct and journeying onto land?
How do you know that journeying onto land was against it's instincts? You are making an assumption without evidence. Do humans defy our instincts when we journey to the stars or the depths of the oceans? We are explorers, we do it to push ourselves. However, most animals continuously expand to new places in order to locate new food supplies and ensure the survival of their species by creating more baskets for all their eggs.