Death is called “Grim Reaper” or “Danse Macabre” is the ultimate or final reality of all living beings whether animals or plants. To beat the death, the species procreate and seek to preserve their identity through numbers of offspring. Lower an species is on the ladder of evolution, more the numbers it produces and believes that survival is in sheer numbers.
Take fish. It is the food of innumerable species of sea creatures and land animals including human beings. They lay their eggs in millions, large portion of it goes unfertilized and even then the fish is there surviving and proliferating. Now rise some higher on the eveolution ladder and you see the frog. It lays less number of eggs but their survival is better than that of fish roes. These eggs are held together in one place by a covering on them. Thus fertilizer is much better.
As we go higher and higher in the ladders rungs, species produce lesser and lesser numbers but then they have to take utmost care of the their offsprings. This process attains the maxima at human beings whose child when born is so helpless to defend and survive and for many years parents have to take care to rear them.