Four seas entertainment news: earthworm's body structure is very simple, and its skin is very thin. When encountering more salt, it will die of dehydration due to the water in its body. You don't believe that the earthworms that will regenerate after their bodies are cut into two parts are afraid of salt. Why are the earthworms afraid of salt? I've sorted out the reasons why the earthworms are afraid of salt for you to see. I hope you can get something in the reading process!
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The reason why earthworm is afraid of salt
Earthworm's body structure is very simple, and its skin is very thin. When it meets more salt, it will die of dehydration due to the water in its body.
The body wall of earthworm is composed of cuticle, epithelium, circular muscle layer, longitudinal muscle layer and coelom epithelium. The outermost layer is a single layer of columnar epithelial cells, whose secretions form a cuticle. The membrane is very thin, composed of collagen fiber and non fiber layer, with small holes on it. Among the columnar epithelial cells are glandular cells, which are divided into mucus cells and protein cells. They can secrete mucus and make the body surface moist. When earthworm encounters severe stimulation, mucus cells secrete a lot and wrap around the body to form mucus membrane, which has protective effect. There are short basal cells at the base of epithelial cells, which are thought to develop into columnar epithelial cells. Sensory cells aggregate to form sensory organs, which are scattered among epithelial cells, and the base is connected with a thin layer of nerve fibers under the epithelium. In addition, there are also photoreceptor cells, which are located at the base of the epithelium and are also connected with the nerve fibers below.
The muscle of earthworm belongs to twill muscle, which generally accounts for about 40% of the whole body volume. It is well-developed and flexible. The longitudinal muscle layer of some body segments of earthworm contracts, and the circular muscle layer relaxes, then the body segments become coarser and shorter, and the setae protruding from the oblique side of the body wall and inserting into the surrounding soil; At this time, the circular muscle layer of the former segment contracts, and the longitudinal muscle layer relaxes. This segment becomes thinner and longer, and the bristles retract, and it is out of contact with the surrounding soil pendulum. Thus, the bristles support of the latter segment pushes the body forward. In this way, the contraction wave of muscle is gradually transmitted from front to back along the longitudinal axis of the body.
The body cavity is divided into many coelomic compartments by the septum according to the body segments, and each compartment is connected by small holes. Each coelomic chamber is developed from the left and right coelomic sacs. The wall coeloma was formed on the outside of the coelomic sac, and the back and ventral mesentery were formed on the inside except the middle part. The ventral mesentery of earthworm degenerated, only the part between intestine and ventral vessels existed, while the dorsal mesentery disappeared. The part between the anterior and posterior coelomic cysts clings together to form septum. Some species have no septum in the esophagus.
Living habits of earthworms
Earthworm is a variable temperature animal. Its body temperature changes with the change of external environment temperature. Therefore, the dependence of earthworms on the environment is generally more significant than that of constant temperature animals. The environmental temperature not only affects the body temperature and activity of earthworms, but also affects their metabolism, growth, development and reproduction, and the temperature also has a greater impact on other living conditions, thus indirectly affecting earthworms. Therefore, temperature is one of the most important living conditions for earthworms.
Generally speaking, the activity temperature of earthworm is in the range of 5-30 ℃, 0-5 ℃ enters into the dormancy state, and it dies below 0 ℃. The most suitable temperature is about 20-27 ℃, at this time, earthworm can grow, develop and reproduce well. When the temperature is 28-30 ℃, it can maintain certain growth; when the temperature is above 32 ℃, it stops growing; when the temperature is below 10 ℃, it becomes sluggish; when the temperature is above 40 ℃, it dies, and the optimum hatching temperature is 18-27 ℃. It can be seen that the highest lethal temperature of earthworm is lower than that of other invertebrates. It's better for the farm to be indoors. In the south, it's ventilated and moisturized in summer. In winter, as long as the window is closed and insulated, it can be produced normally all year round (the temperature here refers to the temperature of the base material, because the temperature of the air is different from that of the base material, for example, when the air temperature is 0 ℃, the temperature of the base material is about 12 ℃; When the air temperature is 38 ℃, the temperature of the base material is only about 28 ℃, which is because the excrement material contains very high moisture).