Lake sturgeons are the largest native fish to Wisconsin and the Great Lakes. Lake sturgeons are one of 23 different sturgeon species, which are living relics. This ancient species made its firs appearance around 100,000,000 years ago in the Upper Cretaceous period of the Mesozoic era, around the time that dinosaurs made their abrupt exit from Earth.
.gif) Lake sturgeons retain many primitive characteristics that have been lost or modified in other modern-day fish. Like a shark, sturgeons have a heterocercal caudal (tail) fin, where the upper lobe is longer than the lower. Instead of a backbone with separate vertebrae, the sturgeon has a continuous, flexible, cartilage-encased rod called a notochord. This rod runs the length of the body and ends at the tip of the upper tail. In addition, sturgeons don’t have scales like modern fish, but bony plates called scutes. Lake sturgeon has five rows of such body armor, two on each side and one along the back.
Another distinguishing feature of the lake sturgeon is four barbels, or feelers, that dangle in front of the mouth. The barbels are important sensory organs that alert the sturgeon to the presence of food. A bottom feeder, their mouth protrudes to suck up food consisting of snails, insect larvae, leeches, small clams and other invertebrates.
|