Sturgeons are scaleless except for five rows of large, pointed, platelike scales running along the top and sides of the body. Their skeleton is part bone and part cartilage, placing them midway between sharks and bony fishes. They are confined to Northern Hemisphere waters. The marine species live as adults in marine waters but return to freshwater rivers and streams to breed. They locate food by their sensitive barbels and by taste buds located outside and around the mouth.
Small invertebrates comprise the bulk of their diet.
The roe are usually taken by killing the female, but because females may take up to 12 years to reach maturity, this method has caused drastic reductions in sturgeon populations. Sturgeons have also been caught for their flesh and oil. Four genera of sturgeons are recognized. Huso is distributed from the Adriatic Sea drainage to the Amur River in Eurasia. One species, the beluga, H. huso, is the largest of all freshwater fishes.