How many animal and plant species live in the Caspian Sea?

Approximately 850 animal species and more than 500 plant species live in the Caspian Sea.

While this number of species is relatively low for a body of water of its size, a significant portion of them are endemic, meaning they are found only in the Caspian Sea. The biological life of the sea has been heavily influenced by changes in salinity over time. Blue-green algae and diatoms make up the largest concentrations of biomass, alongside various species of red and brown algae. Animal life includes a variety of fish—such as sturgeon, herring, pike, perch, and sprat—as well as mollusks, sponges, and the Caspian seal, which is the only mammal native to the sea.12