Sturgeon

Sturgeon are a special group of fish with 27 different species, all belonging to the family Acipenseridae. These fish have been around for a very long time, with the earliest fossils found 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, between 174 to 201 million years ago. 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, spindle-shaped 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, but one huge beluga sturgeon was found in the Volga Delta in 1827, measuring an amazing 7.2 meters! These fish often swim near the bottom of rivers and lakes, feeding on small creatures there.

Unfortunately, many sturgeon species are in big trouble. People have taken too many of them for their eggs, which are made into a special and expensive food called caviar. Because of this and other problems, most sturgeon species are now critically endangered, meaning there are very few left and they could disappear forever if we don’t help protect them.

Etymology

The word "Sturgeon" in English comes from old words used in different languages. It started in Middle English as sturgiun, which came from Old French estorjoun. Before that, 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, including Baltic, Germanic, Greek, Romance, and Slavic 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, which makes them interesting to scientists.

Sturgeons have been hard to classify because they look very similar to each other and can even produce young with other sturgeon species. 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 different types 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.

Most 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. However, some sturgeon live only in fresh water, such as the lake sturgeon and the Baikal sturgeon, either naturally or because humans changed their environment.

Physical characteristics

Sturgeons have some interesting features that set them apart from other fish. Unlike many fish, their skeletons are made mostly of soft, flexible material called cartilage, similar to sharks. They also have a special, soft rod-like structure running through their bodies 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 quite 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 between 100,000 to 3 million eggs, but not all will have babies. The eggs stick to the bottom and take 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 mainly eat shellfish, crustaceans, and small fish. Some types, like the beluga sturgeon, kaluga sturgeon, white sturgeon, and pallid sturgeon, mostly eat other fish when they grow up. They eat by stretching out their siphon-like mouths to suck food from the river or lake bottom. Since they don’t have teeth, they can’t grab prey, 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 special sense called electroreception, to detect electric fields from other animals or natural sources.

Many sturgeons jump completely out of the water, making a loud splash that can be heard far away. Scientists aren’t sure why they do this, but it might help them talk to each other, catch flying food, show off during mating, or help them lay eggs. Other ideas are that it helps them escape danger, get rid of parasites, or just feels good. Sometimes, leaping sturgeons have landed in boats and hurt people.

Interactions with humans

Sturgeons are important to humans mainly because of their eggs, which are made into caviar, a special food many people enjoy. In the past, especially in the 1800s, the United States was the main place for getting caviar from sturgeons. But over time, too many sturgeons were caught, and their homes were damaged, so their numbers dropped a lot. 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, losing their homes, and dams that block their travel. Many kinds of sturgeons are in danger of disappearing. Groups all over the world work to help save sturgeons by studying them, protecting their homes, and sharing information. 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.