- Pallid sturgeon are similar in appearance to the more common shovelnose sturgeon. Both species inhabit overlapping portions of the Missouri and Mississippi River basins. In their original description, Forbes and Richardson (1905) noted that pallid sturgeon differed from shovelnose sturgeon in size, color, head length, eye size, mouth width, barbel length ratios, ossification, gill raker morphology, number of ribs, and size of the air bladder. In general, mature pallid sturgeon grow to larger sizes than mature shovelnose sturgeon. Additionally, pallid sturgeon have wider mouths and unscaled or lightly scaled bellies compared to shovelnose sturgeon that have bellies with large embedded scales.
- The pallid sturgeon has a distinctive appearance that has been referred to as “primitive”, “dinosaur-like” and even “ugly”.
- They are generally between 30 and 60 inches (760 and 1,500 mm) in length and weigh as much as 85 pounds (39 kg).
- Pallid sturgeon are much paler in coloration with grayish white backs and sides, while shovelnose sturgeon are brown. The pallid turn whiter as they age.
- Pallids have a flat shovel-shaped snout & a long slender tail that is heterocercal, with the top tail fin being longer than the bottom fin.
- The mouth is located well back from the tip of the snout. Lacking teeth they use their extendable mouths for sucking small fishes and invertebrates from the river bottom.
- They also have four barbels which descend from the snout near the front of the mouth. The barbels are believed to be sensory features to locate food sources. With the pallid sturgeon, the two inner barbels are shorter than the outer ones, while on the shovelnose sturgeon, all four barbels are the same length. The inner barbels of the pallid sturgeon are positioned in front (anterior) of the outer ones, whereas those on the shovelnose sturgeon are all located in essentially a straight line. The length and positioning of the barbels is one of the best ways to distinguish the two species.
- Pallid sturgeon are lacking the scales or bones found in more modern species of fish. Instead, they have cartilaginous skeletons with five rows of thick cartilage plates that extend along their sides, undersides and backs, as well as over most of the head. These thick cartilage plates serve as a protective armor.The bony cartilage also extends along the backside, from the dorsal fin to the tail.