Why can an earthworm survive after being cut in two?
Earthworms are lower annelids, with a head, tail, mouth, stomach, intestine and anus. The body appears to be made of two tubes with pointed ends fitted together, while the outer layer is a body wall joined ring by ring, and inside the body a digestive intestine runs from head to tail through layer after layer of septa. Let's take a look below at why an earthworm can survive after being cut in two!
Why can an earthworm survive after being cut in two?
When an earthworm is cut into two segments, the muscle tissue at the cut surface contracts immediately, and part of the muscle quickly dissolves itself to form a new cell mass. At the same time, white blood cells gather at the cut surface to form a plug, causing the wound to close quickly. The primordial cells located in the septa of the body cavity quickly migrate to the cut surface and, together with the self-dissolved muscle cells, form nodular regeneration buds on the cut surface. At the same time, cells of tissues such as the digestive tract, nervous system and blood vessels in the body rapidly grow into the regeneration buds through extensive mitosis. As the cells continue to multiply, a new head grows from the cut surface of the segment lacking a head, and a tail grows from the cut surface of the segment lacking a tail, so that one earthworm becomes two complete earthworms.
What food do earthworms eat?
Earthworms are omnivorous animals. Except for glass, plastic and rubber, they eat humus, animal droppings, soil bacteria, fungi and the decomposition products of these substances. Their sense of taste is keen; they like sweet and sour flavors, dislike bitter flavors, prefer heated, softened and fine feed, and are especially greedy for animal food. Each month they eat an amount equivalent to their own body weight, and about half of the food passes through the digestive tract and is excreted as droppings.
What are earthworms afraid of?
1. Afraid of strong light: Earthworms are negatively phototactic, especially avoiding strong sunlight and blue light, but they are not afraid of red light and tend toward weak light.
2. Afraid of soaking: If earthworms are submerged in water, most immediately flee; those that cannot escape show a swollen body and reduced vitality.
3. Afraid of vibration: Earthworms like a quiet environment, requiring low noise and no vibration; after being subjected to vibration they appear restless and try to escape.
4. Afraid of stuffy air: Earthworms need good ventilation in order to replenish oxygen and expel carbon dioxide, and they are especially sensitive to ammonia, smoke and similar substances.
5. Afraid of pesticides: Earthworms are afraid of pesticides. In farmland or orchards where pesticides, especially highly toxic pesticides, have been used, the number of earthworms is small.
6. Afraid of acids and alkalis: Earthworms are very sensitive to acidic substances. It is best to adjust the feed to weakly acidic, as this is beneficial for the digestion of proteins and other substances.