Principle #1 Genetic Variation There are 2 types of sharks there are those who have dull teeth and are small and there are those with very sharp teeth and are big. Sharks prey on seals, sea lions,smaller fish, and other marine mammals.
Principle #2 Overproduction & Struggle for Survival Unlike most fish, shark's eggs are fertilized inside the female's body. The male shark has "claspers," extensions of the pelvic fins that are used to transfer sperm to the female and fertilize her eggs. The shark are on top of there food chain and nothing can eat them.
Principle #3 Differential Survival and Reproduction Those males and females with sharp teeth and big body tend to survive and catch prey more easily while it is harder for those with a small body and dull teeth to catch prey, survive, and reproduce.
Princple #4 Change in Gene Pool The sharks who have sharp teeth and a big body are those who are going to grow in population and keep reproducing and the sharks with dull teeth and small body are going to decrease in population