A class of invertebrates, dioecious, cylindrical, unsegmented, with a few bristles. What lives in the sediments of the sea floor is also called sea intestines.
The common name of Echinococcus monocytogenes is Echinococcus, Echinococcus Heterocystis, Echinococephalidae, Echinococcus, Echinoidea. Body thickness, about 100-300mm long, about 25-27mm wide and 200mm-250mm long, and the body surface is covered with granular protrusions of different sizes, which are conical; Abdominal bristles 1 pair, thick; There is a circle of 9- 13 brown tail hair around the anus. It is distributed in Russia, Japan, Korea, the Yellow Sea and Bohai Sea in China, and is a common benthic species in the intertidal zone and shallow water area of coastal sediment reservoirs in northern China.
Morphology and function
The beetle's trunk is saccate, and its body wall has three layers of muscles. There is a muscular but non-contractible, tactile kiss at the front of the trunk. The kissing part is flexible, and some kinds of kisses can stretch very long. The mouth is the basis of kissing. There are a pair of bristles behind the ventral mouth; The anus is located at the rear end of the abdomen, surrounded by 1 or 2 circles of bristles. Body cavity contains body cavity fluid, and there are two types of cells in body cavity fluid; In some species, cells in body cavity fluid contain respiratory pigments similar to heme. The digestive tract is highly spiral, accounting for a large part of the trunk length, with rainbow tubes (or lateral intestines) and unknown functions. A pair of anal sacs extend from the end of the intestine, which has the function of excretion. One or more protokidneys are attached to the ventral body wall. Many species have a closed circulatory system, which consists of dorsal blood vessels, ventral blood vessels and neurointestinal blood vessels. There is an abdominal nerve cord. The gonad comes from the coelomic membrane above the nerve cord or other parts near the cloaca, which is diffuse, and eggs or sperm are discharged into the coelomic fluid.
The way of feeding varies according to the size of the kiss. When the species with long snouts eat, they stick their snouts out of the acupoints where they live and stick them on the food particles around the entrance of acupoints. Food particles stick to strings of mucus and are sent to the mouth. The species with short snouts secrete mucus at acupoints, forming a mucus tube lining the inner wall of acupoints. The water flow continuously breathes through the acupoints, and food particles enter the acupoints with the water flow and stick to the mucus tube. After a certain amount of food particles are attached to the mucus tube, insects swallow the mucus tube with food particles attached.
classify
At first, tabanids and salamanders were grouped together, and later sedgwick classified them as annelids. However, many people do not accept the classification system of tabanidae belonging to annelids. After W. W. Newby studied the embryo and development of ——Urechi scaupo in 1940, people classified tabanidae as an independent phylum.