A sturgeon is a large, ancient fish that has existed almost unchanged for over 200 million years, swimming in rivers and coastal waters long before dinosaurs disappeared. These remarkable fish can grow enormous: some species reach 18 feet long and weigh over 3,000 pounds, making them among the largest freshwater fish in the world.

Sturgeons look prehistoric, with bony plates called scutes running along their bodies instead of regular scales, and four whisker-like sensors called barbels dangling near their mouths to help them find food along river bottoms. They have no teeth. Instead, they use their tube-like mouths to vacuum up small creatures from the mud.

These fish are famous for their eggs, called caviar, which people consider a delicacy. Unfortunately, this made sturgeons extremely valuable, and overfishing brought many species close to extinction. Some sturgeons live incredibly long lives, over 100 years, and don't reproduce until they're 15 or 20 years old, which makes it hard for their populations to recover.

Today, many sturgeon species are protected by law. The beluga sturgeon, lake sturgeon, and Atlantic sturgeon are all endangered, and scientists work to restore their populations through conservation programs. These living fossils remind us that some creatures have survived countless changes to our planet.