a something becomes larger it is able to act upon more of something else & fins move animals through water by pushing against water ->  the larger and animal's fin is, the more water it can push against  the larger and animal's fin is, the more water it can push against & the more water an animal's fin pushes against, the faster that animal will move through water ->  the larger an animal's fin is, the faster it can move through water  the larger an animal's fin is, the faster it can move through water & fins are a part of aquatic animals used for moving through water ->  large fins can be used to move quickly through water  if an organism 's prey moves quickly then that organism may need to move quickly to catch its prey & a predator is a kind of organism ->  if a predator's prey moves quickly then that predator may need to move quickly to catch its prey  if a predator's prey moves quickly then that predator may need to move quickly to catch its prey & eating prey requires catching prey ->  some predators move quickly to catch prey  large fins can be used to move quickly through water & some predators move quickly to catch prey -> large fins can be used to move quickly through water in order to catch prey