Darwin did many interesting and meaningful experiments on the feeling of earthworms. First, he plays the piano, trumpet and flute for earthworms.
Son, look at their reaction. However, no matter how lively his instrument is, the earthworm always doesn't respond. Finally, Darwin
The conclusion is that earthworms are deaf and can't hear at all. However, when the earthworm just got out of the hole, Darwin made a knock.
Sound, it returned to the hole. Strange! Since earthworms can't hear music, how can they hear knocking at the door? pass by
After many experiments and thinking, Darwin made it clear that this was because the sound of knocking shook the soil at the mouth of the cave. Earthworms have no ears.
Flowers, but there are many sensory cells on the body wall. As long as there is a little vibration outside, it can feel it.
Darwin put earthworms in a container and carried out experiments by moving various objects of different colors, shapes and sizes. Whether it's
Moving an object from far to near or from near to far, or from left to right or from fast to slow will not cause any response from earthworms.
Earthworms seem to be blind. Later, he put the earthworm in a box and opened a small hole on one side of the box to let the light pass through.
Go through this little hole. A few hours later, all the earthworms in the box climbed to the dark end of the box. Then, he used a comparison
Strong light stimulates the earthworm, and the earthworm will quickly flee back to the hole. Through the above experiments, Darwin found that earthworms have no eyes, but
The ability to feel light.
Modern zoologist's research has proved that all parts of earthworm's body, except its ventral surface, are distributed with organs that can feel light, so it can be distinguished.
Don't look at the intensity of light. This kind of light sensory organ is mostly distributed in the front lobe of the mouth and several body segments at the front end of the body, but less at the back end of the body.
Where did the teacher get some earthworms in the inquiry class? Let's observe the external morphology of earthworms.
Each group will be assigned two or three earthworms, one of which is longer and the other is shorter. First, we measured the body length of the earthworm. The long one is ten centimeters and the short one is eight centimeters. They are put on paper, they look dark, and there is some shit behind them, which is really disgusting. Look carefully, its tail is bigger and stronger, while its head is slightly smaller, which will stretch. The body is turquoise, composed of many links, and there are many bristles on each section, but you can't see it without looking carefully. Teacher Li asked us to press its head. Suddenly, it jumped up like a lively big herring. The teacher asked us to observe carefully whether the earthworm has a mouth. We watched with interest, but we really couldn't see it. I used an ordinary magnifying glass. Although it was a little blurred, I still saw its mouth. Huang shouted, "Earthworms have mouths, and their mouths are like suckers." The teacher asked us to observe again. How did it climb up? "The students found that it sucked the ground with its mouth first, its head was fixed first, its whole body bowed forward, its tail shrank, and its whole body moved forward a little. Every time it moves, the distance it moves forward is about 1.5 cm. Then, we press its head to stop it from moving forward. We were surprised to find that the earthworm can walk in the direction of its tail.
In this class, the teacher also showed us relevant information: this kind of earthworm is only one kind of earthworm family, called hookworm. It has a long body and is made up of many similar parts. There are countless bristles on the body surface, and there is a deep groove between nodes, called internode groove, and a shallow groove on the node, called ring. ...
There are so many puzzles in this world that we need to explore constantly. As long as we observe carefully, we will be able to solve it.
Hi! This inquiry class is really great! I'm telling you, we're going to cut these alive earthworms, and we're going to do an experiment to explore the regeneration ability of earthworms.
2 Experimental process:
On the basis of observation, the whole class was divided into four groups, of which two groups carried out experiments according to scheme 1 and the other two groups carried out experiments according to scheme 2.
Experimental steps:
(1) Cut 10 earthworm in the center with a sharp knife. It is required to cut quickly and the incision should be smooth.
(2) Observation record: Earthworms are in pain, and both ends twist in a jumping way at the same time; A small amount of red blood flowed out of the incision, and a large amount of turbidity flowed out; After about 10 seconds, the earthworm stopped beating and began to crawl, indicating that the injured earthworm did not die.
(3) Divide 20 injured earthworms into two parts and put them in two bottles respectively. The degree of dryness and wetness of the soil and the content of organic nutrients in the two bottles are different.
(4) Cut other 10 earthworms into three sections.
(5) Observation record: pain, jumping at both ends, slightly twisting in the middle, and blood and feces flowing out.
(6) The earthworm segments at both ends and in the middle are respectively stocked in two bottles, and the soil components in the two bottles are the same.
Fourth, late observation.
date
Situation record
2 days
The wound is not healed, there is mud, there is no blood flow, and it is wet; There is no obvious activity. Five earthworms died in the middle.
7 days
The wound is not completely healed, with hidden scar combination, slightly dry and more active than before. Three people died in a bottle because of too much water; The earthworms in the middle part are all dead.
14 days
The wound is completely healed, the scar is thick and raised, and the activity is more active.
20 days
Return to normal growth.
Comparison and statistics of verbs (abbreviation of verb)
Through experiments and observations, the following conclusions are drawn: Earthworms have strong regeneration ability. Under the suitable growth environment, the injured earthworm recovered to health and grew normally for about 20 days. The regeneration and survival of earthworms are closely related to soil fertility and soil moisture. It is found that the survival rate of earthworms is high in an environment with fertile soil and moderate soil humidity, and the humidity in the soil is the key to affect the survival rate of earthworms. (See the table below) In addition, the reason why the middling earthworm is not easy to survive needs further study.
List of relationship between earthworm regeneration and environment
Soil condition
Earthworm survival rate
The soil is fertile and loose, and the humidity is suitable.
90%
The soil is dry and hard.
75%
The whole process of growth, development and reproduction experienced by earthworms in their lifetime. Life history includes the occurrence, formation and fertilization of germ cells, as well as the aging and death of adults. Artificial is generally divided into three stages: earthworm cocoon formation, embryonic development and post-embryonic development.
1. cocoon formation
(1) Germ cell generation: With the growth of individuals, the gonads gradually develop, and the process of germ cell generation gradually proceeds in them. In a certain period, they are discharged into seminal vesicles or oocysts, and further develop into sperm or eggs. Mature sperm includes three parts: head, middle section and tail. The total length is 72 microns. Some of them can be as long as 80-86 microns (twice the length of human sperm). Earthworm eggs are mostly spherical, oval or pear-shaped. The eggs of terrestrial earthworms are smaller than those of aquatic earthworms. The diameter of Eisenia foetida egg is only 0. 1 mm, which is composed of egg membrane, egg cytoplasm, egg nucleus and the outermost thin yolk membrane secreted by the egg itself.
(2) Earthworm mating: Earthworms fertilized by the same species fertilize each other through mating after sexual maturity. That is, the egg is transferred to the other person's seminal vesicle for temporary storage. When mating, the two earthworms face down and their ventral faces stick together. The ring area of one earthworm is facing the spermatic foramen area of another earthworm. Mucus secreted by the annular band adheres closely to the spouse. There are two slender mucus tubes between the rings of two earthworms, which bind the corresponding segments (VIII-XXXIII) of their spouses together. The ventral surfaces of two earthworms attached to Eisenia foetida are relatively sunken, forming two longitudinal semen grooves. The semen discharged from the male hole, due to the regular contraction of the arch muscle in the sulcus, is transported backward to its own annular belt and enters the seminal vesicle of the other side. When mutual fertilization is completed, the two earthworms retreat from opposite directions and exit the mucus tube that binds the earthworms. Until the spouse lost contact. The above mating process takes about 2-3 hours. The mating of wild earthworms mostly occurs in fertilizer piles in early summer and autumn. Artificially propagated earthworms can mate all year round as long as conditions are suitable.
(3) Ovulation and fertilization: Ovulation refers to the process in which earthworms expel eggs through the female foramen. Because there is no movement device, the eggs in the oocyst or body cavity are passively discharged through the female orifice mainly through the oscillation of the cilia on the egg funnel and fallopian tube. The female hole is often located in the center of the ventral surface of the first belt (earthworm), so the eggs are directly discharged into the earthworm cocoon formed by the belt. The young earthworm cocoon containing one or more eggs, because the muscles of the back body wall contract more strongly than the front body wall, there is a lot of mucus between the young earthworm cocoon and the body wall for lubrication, the contact between the periphery of the young earthworm cocoon and the ground is blocked, and the earthworm body retreats, so that the front end of the earthworm body gradually withdraws from the young earthworm cocoon. When the seminal vesicle hole passes through the young earthworm cocoon, the foreign semen stored during mating is discharged into the young earthworm cocoon. So as to complete the fertilization process.
(4) cocoon formation. The whole process of earthworm cocoon formation begins with the secretion of earthworm cocoon membrane and its slender mucus tube outside, ends with ovulation, and until the young earthworm cocoon falls off from the front end of the earthworm body and is closed at the front and back. There are not only eggs in earthworm cocoons, but also protein solution for sperm and embryo development.
Origin of earthworm cocoons: Earthworms of Ortholumbridae, such as Eisenia foetida, Eisenia foetida and Eisenia tremella, generally produce earthworm cocoons on the surface of moist soil, which will go deep when encountering drought. Earthworms are mostly produced in humus layer, and Eisenia foetida is mostly produced in compost.
Color of earthworm cocoons: The newly produced earthworm cocoons are mostly light yellow and light yellow, and then gradually turn yellow, light green or light brown, and finally may turn dark brown, purple and olive green.
Formation of earthworm cocoons: most of them are spherical and oval, some are bag-shaped, vase-shaped or spindle-shaped, and a few are slender, fibrous or tubular. The ends of earthworm cocoons protrude, and some of them are clustered, stem-shaped, conical or umbrella-shaped.
Cocoon size: The cocoon size is generally positively correlated with the width of the insect body. There is a big difference. Eisenia foetida is generally 3.8-5.0mm long and 2.5-3.2mm wide.
Egg content of earthworm cocoon: Different kinds of earthworms have different egg content. Some contain only one egg, some contain multiple eggs, such as Eisenia foetida generally contains 3-7 eggs, but some earthworm cocoons only contain 1 or 20 or even 60 eggs.
Production of earthworm cocoons: The annual output of earthworm cocoons varies with species, individual development, climate and food factors. The production of wild earthworm cocoon has obvious seasonality. In harsh environment (dry, high temperature, etc.). ), it is possible to produce more earthworm cocoons in a short time. Some earthworms (such as Eisenia foetida) that inhabit the surface soil usually produce more earthworm cocoons than those that dig holes in the deep soil (such as Eisenia annulata). Under the good conditions of artificial feeding, earthworms can produce earthworm cocoons all year round. Under the condition of 20-26℃, each earthworm produces 0.35-0.80 earthworm cocoons every day.
Embryonic development: The embryonic development of earthworm refers to the whole development process from fertilized egg to young earthworm (i.e. hatching), and its morphological and structural characteristics are basically similar to those of adult earthworm. It includes three stages: cleavage, embryonic development and organogenesis. The completion of earthworm embryo development is the end of earthworm cocoon incubation process. The incubation time and the number of larvae hatched from each earthworm cocoon vary with ecological factors such as species, temperature and humidity during incubation. Eisenia foetida generally hatches 1-7 larvae from each earthworm cocoon, and the incubation time is 2- 1 1 week.
3 Postembryonic development
Young earthworms hatch from their cocoons, grow and develop to sexual maturity and reproduction, and then gradually age and die. This process is the postembryonic development (that is, life span) of earthworms. The growth of earthworms generally refers to the increase of the weight and volume of earthworms. Development refers to the process of earthworm's structure and function from simple to complex. The two are different and inseparable.
The growth curve of earthworm is generally S-shaped. That is to say, before reaching sexual maturity, the body length and weight of young earthworms increased sharply. From sexual maturity (the appearance of bands) to aging (the disappearance of bands), the weight increased little, but the reproductive ability was very strong. Once the belt disappears, the weight gradually decreases. The postembryonic development time of earthworms often varies from species to species. Eisenia foetida for 55 weeks. 50-week-old earthworms have different lips. Under natural conditions, earthworms at different development stages are often in the same environment, and their composition often changes with the seasons. Many earthworm cocoons produced in late autumn are too late to hatch in the north, so the proportion of earthworm cocoons in winter is large. There are more adults in spring. In June (summer), due to the hatching of earthworm cocoons, the number of larvae increased sharply, and gradually decreased after autumn, while the number of adults with larger weight gradually increased.
The life span of earthworms varies with species and ecological environment. A kind of double-breasted earthworm has a life span of only two-quarters under arid and barren conditions, but it can be extended to more than two years under better environmental conditions. Earthworms are annual earthworms with a life span of 7-8 months. Under ideal conditions, earthworms have a longer potential life span. For example, Eisenia foetida may live for four and a half years. Six years of earthworm. Earthworms with different lips are ten years and three months.
According to experiments, it takes 24-28 days for the cocoon to hatch into a young earthworm and 30-45 days for the young earthworm to grow into an earthworm at an average room temperature of 265438 0℃. 5- 10 days after adult mating. The average generation interval of each earthworm is 59-83 days.
Soil is not only the food source of wild earthworm, but also its habitat. The soil contains the necessary environmental conditions for earthworms to live, and various ecological factors have complex effects on earthworms.
From a national point of view, the distribution and density of earthworms vary greatly with regions, soil types, seasons, temperatures and the amount of organic matter.