Sturgeon

Sturgeon are a special group of fish with 27 different kinds, all in the family Acipenseridae. These fish have been around for a very long time, with the earliest fossils from the Late Cretaceous period. They are related to other ancient fish called acipenseriform fish, which lived as far back as the Early Jurassic period.

Today, sturgeons live in rivers, lakes, and coastlines across Eurasia and North America, and they were once found in northern Africa too.

Sturgeons look quite unique. They have a long body without scales, but instead, they have five rows of bony plates called scutes along their sides. Many species can grow very big, usually between 2 to 3.5 meters long.

Unfortunately, many sturgeon species are in big trouble. People have taken too many of them for their eggs, which are made into a special food called caviar. Because of this, most sturgeon species are now critically endangered, meaning there are very few left.

Etymology

The word "Sturgeon" in English comes from old words in different languages. It started in Middle English as sturgiun. This came from Old French estorjoun. Even earlier, it was styrġa in Old English. All these words share a common root from an ancient Proto-Germanic language *sturjô.

People traded sturgeon in ancient Europe, so the word spread to many languages. Scholars think the word may have come from a very old language near the Volga river, where people caught and sold sturgeon, or it might have roots in Proto-Indo-European *_str̥(Hx)yón'-.

Evolution

Sturgeons are a group of fish that have been around for a very long time. Their fossils first appeared about 174 to 201 million years ago, during a time called the Early Jurassic. They are some of the earliest ray-finned fish still living today. True sturgeons show up in fossils from about 100 to 94 million years ago, in a place called the Cenomanian in Canada. Over millions of years, sturgeons have changed very little.

Sturgeons have been hard to classify because they look very similar to each other. They come from bony fishes and have evolved slowly. There are 27 different kinds of sturgeons today, grouped into five main families. These fish live in many parts of the world, from North America to Europe and Asia.

Range and habitat

Sturgeon live in many kinds of water, from warm to very cold, in both North America and Eurasia. In North America, they are found along the Atlantic Coast from the Gulf of Mexico to Newfoundland, including big lakes like the Great Lakes and important rivers such as the St. Lawrence, Missouri, and Mississippi. They are also in rivers along the West Coast from California to British Columbia. In Europe, sturgeon live along the Atlantic coast, including in the Mediterranean and rivers in North Italy. They are also found in rivers that flow into the Black, Azov, and Caspian Seas, and in northern rivers of Russia that empty into the Arctic Ocean. Some sturgeon live in rivers of Central Asia and in Lake Baikal. In the Pacific Ocean, they live in the Amur River near the border of Russia and China, on Sakhalin Island, and in some rivers in northeast China.

Many sturgeon species are in danger because of habitat loss, overfishing, and pollution. They usually lay their eggs in fresh water but feed in areas where salt and fresh water mix. Some sturgeon live only in fresh water, such as the lake sturgeon and the Baikal sturgeon.

Physical characteristics

Sturgeons have special features that make them different from other fish. Their skeletons are made of soft, flexible material called cartilage, like sharks. They have a soft rod-like structure that helps them stay upright.

These fish are easy to recognize because they have long, slender bodies, flat noses, and tough plates called scutes instead of regular scales. They also have four special sensing organs called barbels in front of their mouths, which they use to find food on the river bottom. Some sturgeons, like the beluga in the Caspian Sea and the kaluga in the Amur River, can grow very large—over 5.5 meters long and weighing more than 2,000 kilograms. They can also live for more than 100 years, making them unique in the animal world.

Life cycle

Sturgeons live a long time, often for 50 to 60 years. They don’t start having babies until they are about 15 to 20 years old. These fish need special conditions to have babies, like the right light in spring, clear shallow water with rocks or gravel, and the right temperature.

A female sturgeon can release many eggs, but not all will hatch. The eggs stick to the bottom and take about 8 to 15 days to become baby fish. These babies float downstream to slower water areas where they grow and eat insects and small water animals. In their first year, they grow to about 18 to 20 centimeters long and then move back to faster river currents.

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Behavior

Sturgeons eat shellfish, crustaceans, and small fish. Some types, like the beluga sturgeon, kaluga sturgeon, white sturgeon, and pallid sturgeon, eat other fish when they grow up. They eat by stretching out their mouths to suck food from the river or lake bottom. They don’t have teeth, but bigger sturgeons can swallow very large food, even whole salmon. They don’t use their eyes to find food. Instead, they use special sensors on their heads, including four barbels and a sense called electroreception, to detect electric fields from animals or natural sources.

Many sturgeons jump completely out of the water, making a loud splash. Scientists aren’t sure why, but it might help them talk to each other, catch food, show off during mating, or help them lay eggs. Sometimes, leaping sturgeons have landed in boats and hurt people.

Interactions with humans

Sturgeons are important to humans because their eggs are used to make caviar, a special food many people enjoy. In the past, the United States was the main place to get caviar from sturgeons. But too many sturgeons were caught, and their homes were damaged, so their numbers dropped. Now, rules help protect sturgeons, and other countries like Russia are the main places for caviar.

Sturgeons face many dangers today, like being caught too much and losing their homes. Many kinds of sturgeons are in danger of disappearing. Groups around the world work to help save sturgeons by studying them and protecting their homes. These efforts are important to keep sturgeons safe for the future.

Caviar

Further information: Caviar

Conservation

Before the 1800s, parts of sturgeons were used to clear drinks like wine and beer. Some religions have special rules about eating sturgeons. In some places, sturgeons were considered very special and belonged to kings or leaders. They are also symbols in some emblems and coats of arms.