Snail (scientific name: Margarya melanioides): It belongs to Oncomelania, a genus of snails. It is a mollusk with snails and shells in fresh water. The shell is large, the height exceeds 100 mm, and the shape is conical or tower conical; Thick, greenish brown or brown.
Most of them have seven snails, including two original spiral ribs, and the shell surface has spiny or papillary protrusions, or only smooth spiral ribs. This is a horny paper. Androgyny, the male right antenna is short and thick, forming a mating organ. Viviparous, there are 3-7 embryonic snails per 1 sac, and the shell height is above 10 mm, which lives at the bottom of the lake and spreads all over the lake bed.
Living in deep water and shallow water. Snails crawl with wide feet at the bottom of the lake. It mainly feeds on diatoms growing at the bottom of the lake and debris in sludge. Endemic to China, it is distributed in the southwest plateau lakes and found in Dianchi Lake, Erhai Lake, Fuxian Lake, Yilong Lake and Datun Lake.
The top ten freshwater lakes in Yunnan, China are located in the southwest plateau, and are home to many unique large plants and animals, including fish, mollusks and crustaceans. Erhai Lake, Dianchi Lake and Fuxian Lake are the largest. Formed in the late Pliocene and early Pleistocene. They flow into three different river systems.
morphological character
Snails belong to the genus type species. This is a species with snails in fresh water. The shell is large, conical, high 100 mm, thick, greenish brown or brown. Most of them have seven snails, including two primitive spiral ribs. In addition to the original spiral ribs, the upper part of each snail has well-developed inclined shoulders. There are more than 3 rounds, rarely 4 rounds, the spiral edge is strong, and 1 spiral edge decreases at the spiral shoulder.
The first two rounds have a row of spiral small and regular nodules, and the last two rounds have blunt and large nodules. The second edge of the whorl is the most developed, and there are regular protruding nodules on the early whorl and spine or large, irregular nodules or wavy protrusions on the last two rounds; The third rib is always covered by the stitches on it, so it is almost invisible on the spiral line.