"Growth Changes of Silkworms" Animal Life Cycle PPT Courseware

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"Growth Changes of Silkworms" Animal Life Cycle PPT Courseware

Read pages 24 to 26 of the book and think about the following questions:

1. What changes will happen to the silkworm as it grows?

2. What is molting? Why do silkworms shed their skin?

3. What parts does the external shape of silkworm consist of?

4. The silkworm is almost mature. What characteristics will it show? At this time, what should we prepare for it?

Growth changes of silkworms

What changes occur to the silkworm as it grows?

Changes in silkworms include:

1. The color has changed

2. Changes in size (body length, weight)

3. Changes in eating and defecation

Silkworm molt

Do you know what molting is? How many times does a silkworm shed its skin in its life from ant silkworm to cocoon? Why does it shed its skin?

When silkworms grow to a certain stage, they will grow new skin and replace the old skin. This is called molting.

Silkworms shed their skin four times from ant silkworm to cocoon.

Silkworms molt because the outer skin of the silkworm does not grow as the body grows, so when its body grows to a certain extent, the silkworm will replace the old, smaller skin.

How does the life of a silkworm change?

Ant silkworms grow rapidly by feeding, and their body color gradually turns bluish white. When the silkworm grows to a certain level, it needs to shed its old skin and grow a new, wider skin before continuing to grow.

During the molting process, silkworms need to sleep while the new skin is forming, which is called sleep.

Sleep is the boundary that divides the age of silkworms. Ant silkworms are called 1st instar silkworms, 2nd instar silkworms are called after the first sleep, and so on, 5th instar silkworms are called after the fourth sleep. Sleep periods vary in length, from a few hours to a day. Silkworms do not eat or drink during the dormant period.

By the end of the fifth instar, the silkworm will gradually stop feeding, and it will empty its digestive tract and become transparent. At this time, it is called mature silkworm. Mature silkworms begin to spin silk and form cocoons.

Silkworm's appearance

The body of silkworm is long cylindrical and consists of three distinct body segments: head, thorax and abdomen.

Head: Small, located at the front of the silkworm body, oblate in shape.

Thorax: The three links behind the head. There are three pairs of thorax on the thorax, which help the silkworm control the mulberry leaves when eating.

Abdomen: The link behind the thorax. The abdomen has 4 pairs of gastropods and a pair of caudal legs, which are the movement organs of silkworms.

In addition, there are six single eyes on the left and right sides of the silkworm's head, and 9 pairs of small black dots on both sides of the body, which are the silkworm's valves and its respiratory organs.

What else will silkworms grow into?

After the silkworm becomes the fifth instar silkworm, what characteristics of the mature silkworm will it soon show?

After the silkworm molts four times, it becomes the fifth-instar silkworm. Generally, after five to eight days, it will show the characteristics of old age: loss of appetite, transparent chest, and then stop eating completely, the abdomen also becomes transparent, and the head of the silkworm body becomes transparent. It raises its head, spins strands of silk from its mouth, and swings left and right up and down to find a place to form a cocoon.

Preparing for silkworms to spin silk and form cocoons

The silkworm is about to spin silk, what should we prepare for it?

Prepare a place for silkworms to spin silk: use straw to tie a small frame, and paper to make a cylinder or grid room. Once the silkworm is found to be mature, it can be placed in a lattice or shelf.

Summarize

1. During the growth process of silkworms, their length, weight, food intake, etc. will continue to change.

2. Molting is a significant feature of silkworm growth. The body of silkworms will change every time they molt.

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For more information about the PPT courseware "The Life Cycle of Animals and the Growth Changes of Silkworms", please click the "Life Cycle of Animals PPT and the Growth Changes of Silkworms" PPT tag.

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Update Time: 2024-07-04

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