brief introduction

The paddlefish (Polyodon spathula, Latin name), also known as the American paddlefish and the Mississippi river paddlefish, belongs to the ACIPENSER family.

The name and scientific name of the paddlefish come from its unique snout, which is flat and paddle-shaped, especially long. It mainly feeds on zooplankton, but also crustaceans and bivalves.

The paddlefish is one of the last two genera and two species of the family Polypodontidae in the world, and lives in the slow-flowing waters of the Mississippi River. The other is the white sturgeon, which lives in the Yangtze River in China and is almost extinct. The paddlefish is thought to use sensors in its paddle snout to detect prey and to navigate when migrating to spawning grounds.

morphological character

Dorsal fin 50-55, gluteal fin 50-51; Pectoral fin 30-34; Abdominal fins 34-40. Body length is 7.45-8.68 times of body height and 1.47- 1.59 times of head length. The head length is 1.43- 1.53 times of the kiss length, 40.5-48.75 times of the eye diameter, and 8.18 times of the eye interval.

The maximum overall length can exceed 180 cm, and the weight is more than 37 kg. The body length is spindle-shaped, and the pectoral fin is flat at the front and slightly flat at the back. The head is long, and the head length is more than half of the body length. The kiss is paddle-shaped, flat, wide at the front and narrow at the back.

Eyes are extremely small, oval and lateral. The mouth is lower, the mouth is big and arc-shaped, and there are small teeth in both jaws. The branchial foramen is large and not connected with isthmus. The upper part of the operculum membrane is particularly extended and triangular. Gill rakes are slender and dense.

habitat

Acipenser longirostris mainly lives in fresh water, but it is also found in salt water. In large rivers, the long-nosed sturgeon inhabits the reach with moderate velocity and abundant zooplankton. Acipenser longsnout is a kind of swimming fish, which lives in some large rivers in North America.

Adult fish are common in slow-moving rivers and rarely appear in small tributaries. During the flood season in spring, Acipenser longirostris swims from deep water to the slow-flow area with rich bait and the junction of tributaries flowing into the main stream. In late autumn and early winter, return to deep water for winter.