Sturgeons belong to the oldest animal species on earth.
They make high demands on water quality.
Appearance and characteristics:
Skeleton only partially ossified; 5 rows of large scales on the sides; caudal fin asymmetrical;
Mouth subordinate (similar to a shark) and can be unfolded;
digs with its shovel-similar head at the seabed after food; 4 Barteln.
Sturgeons, especially females, become sexually mature very late (partly only after 20 years) until they spawn for the 1st time. Smaller types are already after few years sexually mature.
Through robber-fishery, its continuance decreases in the seas. The eggs of the female sturgeons (Rogen) are regarded as expensive delicacy and come as caviar into the trade. Sturgeons are threatened with extinction.
Adult sturgeons have hardly any natural enemies – humans are their biggest enemy.
Today, 15 of the 27 sturgeon species are acutely threatened with extinction, but all other species are also on the red list.