Freshwater fish.

Expansion:

1. Introduction:

Chinese sturgeon (scientific name: Acipenser sinensis) has an average body length of about 40 cm, with a maximum length of 130 cm, and the highest weight up to 600 kg. The body is spindle-shaped, with a pointed head and a long snout. There are 4 snout in front of the mouth. The mouth is located on the ventral surface. It is stretchable and can be stretched into a tube shape. The body is covered with five rows of large and hard bone scales, one row on the back, one row on the side of the body and the abdomen. Two rows on each side. The sturgeon is a rare ancient fish left over from the Mesozoic Era 150 million years ago. It is between cartilage and hard bone. The degree of ossification of the bones is generally reduced. The central axis is an unossified elastic notochord without vertebrae. Most of the cartilage shell accompanying the skull is not ossified. The caudal fin is crooked, the even fins have a broad base, and the dorsal fin is opposite to the anal fin. The pelvic fin is located in front of the dorsal fin. The bases of the fin and caudal fin have spinous scales. The intestines have spiral valves. The anus and cloaca are located near the base of the pelvic fin. The opening of the fallopian tube is far away from the ovary.

The Chinese sturgeon has a long life cycle, with a maximum lifespan of 40 years. It is a first-level protected wild animal in China and a living fossil. It is also known as the "Giant Panda in the Water". It has high scientific research, medicinal and ornamental value. Distributed in China, Japan, South Korea, Laos People's Democratic Republic and North Korea.

2. Morphological characteristics

The Chinese sturgeon has an elongated body with tapering ends, a narrow back and a straight abdomen. The head is long triangular in shape. The tip of the muzzle is long. The nostrils are large and located in front of the eyes. Blowholes are cracked. The eyes are small, oval, located in the back half of the head. The eyes are widely spaced. The mouth is inferior, transversely cleft, protruding, and can expand and contract. The lips are underdeveloped and have small papillae. There are two pairs of whiskers in the center of the muzzle, arranged in an arch shape. Their length is shorter than 1/2 of the distance between the whisker base and the front edge of the mouth, and the outer whiskers do not reach the corners of the mouth. The gill slits are large and the false gills are well developed. Gill rakers are sparse and short and thick. 1 dorsal fin, posterior position, concave trailing edge, starting point in front of the anal fin. The anal fin is opposite to the dorsal fin, below the middle of the dorsal fin. The pelvic fin is small, rectangular, located behind and below the center of the body, close to the anal fin. The pectoral fins are well developed, oval, and low in position. The caudal fin is crooked, the upper lobe is particularly developed, and there is a longitudinal row of spinous scales on the upper edge of the caudal fin.