Organisms that are r-selected have short life spans, are generally small, quick to mature and waste a lot of energy. K-strategists, on the other hand occupy more stable environments. They are larger in size and have longer life expectancies. They are stronger or are better protected and generally are more energy efficient. They produce, during their life spans, fewer progeny, but place a greater investment in each. Their reproductive strategy is to grow slowly, live close to the carrying capacity of their habitat and produce a few progeny each with a high probability of survival.