Family POLYODONTIDAE 



THE PADDLEFISH FAMILY 



The paddlefishes belong to an ancient group of fossil fishes which 

 are known by several fossils representing two species. Two modern 

 species are living today. One is the paddlefish found in the Mississippi 

 River system and the other is Psephurus gladius, found in the Yangtse 

 River in China. Psephurus gladius is said to reach a length of 20 feet. 

 The paddlefishes are smooth-skinned fishes with the snout prolonged 

 into a long, thin, paddle-shaped projection, which is somewhat flexible. 



GENUS Polyodon Lacepede 



There is only one living species in this genus, the characters of which 

 are given below. 



PADDLEFISH (Spoonbill Cat) 

 Polyodon spathula (Walbaum) 



The paddlefish (Figure 3) is a primitive fish having a skeleton com- 

 posed chiefly of cartilage. It has a long, thin, paddlelike snout extend- 

 ing almost one-third the length of the body. The mouth is broad and 

 subterminal. Small teeth are present only in the younger individuals. 

 The skin is smooth and without scales, though traces of rhomboid scales 

 are found on the upper lobe of the caudal fln. The gills are covered by a 

 large, peculiar soft opercle reaching to the base of the ventral fin and 

 ending posteriorly in a point. A spiracle is present. The tail is hetero- 

 cercal. The color is a uniform leaden gray. Internafly the paddlefish has 

 a swim bladder like that found in most higher fishes. It has a peculiar 

 intestine of the spiral-valve type usually found in sharks. The swim 

 bladder is cellular and is connected by a duct with the esophagus. 



Its primitive, sharklike form, peculiar anatomy, and large size make 

 the paddlefish one of the most interesting fishes found in the Mississippi 

 Valley. It attains a length of over 6 feet and a maximum weight of 184 

 pounds (Kuhne, 1939) . A specimen 5 feet 10 inches long had a paddle 

 16 1/2 inches long and 4 inches wide. The eggs are greenish black, 

 therein resembling the eggs of the rock sturgeon, but are very small as 

 compared with rock sturgeon eggs. 



The breeding habits were largely unknown until reported recently by 

 Thompson (1933) . The young start life without the paddlelike snout, 

 but feed hke the adults. In Illinois the adults apparently spawn in April; 

 in Louisiana they spaw^n in February and March. Nearly ripe females 

 have been procured from Lake Pepin late in May. Alexander (1914) 

 said that in Louisiana the paddlefish are found at the spawning season 

 in schools close to the hard, sandy bottom along the border of lakes. 



73 



