ELI5: Why have crocodiles and alligators survived for millions of years?

Crocodiles and alligators have survived for millions of years because their bodies are built like ultimate, energy-saving survival machines that can handle almost any disaster.

Think of other animals like fancy sports cars: they are fast and exciting, but they need the exact right fuel, warm garages, and constant care to run properly. Crocodiles and alligators, on the other hand, are like tough, old pickup trucks that can drive through mud, run on almost any fuel, and keep working even after a giant storm.

Here is why they are so good at surviving everyday life:

• They have a super-saver battery mode: Just like your tablet or phone can go into low-power mode to keep from turning off, these reptiles can slow down their bodies. They are cold-blooded, which means they do not waste energy trying to keep themselves warm. Because of this, they can rest for months, or even over a whole year, without eating a single bite of food.
• They are not picky eaters: Imagine being able to eat anything in the fridge, even the stuff that has been sitting there for weeks. While some animals only eat one special plant or bug, crocs and gators will eat fish, birds, turtles, or whatever happens to wander near the water. If food gets scarce, they simply adapt and eat whatever is available.
• They wear tough armor: Their thick, scaly skin is like wearing a built-in bicycle helmet and knee pads all over their bodies. This protects them from scratches, bites, and infections. Their bodies are so tough that they rarely get sick, even when living in dirty, muddy swamp water.
• They are master hide-and-seek champions: Their eyes, ears, and noses are all placed on the very top of their heads. This means they can float like a soggy tree log, almost completely invisible under water, while secretly breathing and watching everything around them.