The two shells of the dead bishell mollusk that are closed apart know why

Because after death, the adductor muscle in the shell loses its activity, and it is no longer possible to close the two shells.

The adductor muscle is also known as the fleshy column. It is a mollusk valve gills that close the muscles of the left and right two petals, and the front and back 1 pair, which are called the anterior and posterior obturator muscles, respectively. It penetrates the visceral mass and the mantle and fixes on the inner surface of the shell, and its fixation point is called the obturator muscle mark.

The shell closes by contraction of the adductor muscle, and in order to minimize energy consumption, the adductor muscle can remain tense for a long time, and can close tightly for hours or even days.

In addition, the adductor muscles can contract rhythmically to control the flow of water into and out of the mantle cavity. In the sea fan, the muscles that carry out the movement of water in and out of the outer shell and mantle cavity are separated. The anterior and posterior obturator muscles of clams and other clams are almost equal in size, while the anterior and posterior obturator muscles of hemitasis clams and mussels are much smaller than those of posterior adductor muscles.

The obturator muscle disappears before clams and sea scallops, and only the abnormally developed posterior adductor muscle occupies almost the entire body. The opening of the shell is due to the relaxation of the adductor muscles and the elastic action of the band.

The upper and lower shells of bivalves are closed by internal obturator muscle contractions. After death, the muscles are relaxed, and the corpse is worn out in the water, and the internal organs and muscles are eaten, leaving two empty shells.

The shell opens mainly by the ligaments that connect the two shells; Closure mainly relies on two cylindrical adductor muscles, one in front and one in the back, also known as the fleshy column. The meat column of scallops is the dried scallops sold in stores. When the adductor muscle contracts, the flesh column becomes longer, and the two shells cannot be pulled, and the shells open.

After the clam dies, the adductor muscle loses the ability to contract, so the shell opens.

Find o( o

Right. The body of mollusks is soft, has a mantle, and generally has a shell, in which the body is hidden in order to obtain protection, as the shell will.

hindering activity, so they are quite slow; It is not segmented, and can be divided into three parts: head, foot, and visceral mass, and in vitro**.

membrane, but some shells are degraded, such as squid, there are no shells It can be seen that the description of the stem is correct.

Molluscs (Latin name: granulifusus kiranus) are invertebrate mollusks and are the largest except for arthropods.

of taxa, about 100,000 species.

The systems vary greatly, but there are common features The body is soft and not segmented, and it is generally divided into cephalic-foot (some heads are vestigial or absent; Foot muscles.

and visceral-mantle (composed of the dorsal visceral mass, mantle and mantle cavity).

Hello, no, it's not that the squid doesn't have a shell, but it has a degraded shell in its body, called a sea sheath, which can be used in medicine.

Hello, no, there is no squid, you can take a look at the following detailed classification:

According to the morphological structure of mollusks, it can be divided into the following five classes.

1.Twin nerves are symmetrical from left to right. The head is not obvious. There are often eight pieces of shells, arranged on the back in the form of covered tiles. Foot lumpy. Such as stone turtles, etc.

2.Gastropoda Left and right asymmetry. The head is distinct. The snail shell is spiral-shaped. The foot is often ventral. Such as snails, snails, etc.

3.Digs are symmetrical left and right. The head is not obvious. The foot is cylindrical. The shell is a horn-shaped tube with two ends open. Such as horn shells, etc.

4.Petals are symmetrical. No head. Foot axe-shaped. There are two shells on the left and right. Such as river mussels, oysters, etc.

5.Cephalopods are symmetrical. The body is divided into two parts: the head and the chest (internal organs). Part of the foot becomes a bowl in the shape of a strip and part into a funnel-shaped body. The shell is the shell, or the inner shell, or the none. Such as squid, abalone, etc.

Shell degradation, it cannot be said that there are no shells, not rigorous.

Squid also have degraded shells.

Be. The shells in the phylum molluscs can be divided into five classes: monoplacophora, polyplacophora, gastropoda, bivalvia, and cephalopoda.

Among them, only gastropods and bivalves have freshwater living species, and gastropods also have terrestrial species, these two classes contain more than 95% of the species of mollusks, and the other classes are marine life.

No, it belongs to the phylum Podopoda. Because glandular cells do not fit into the phylum Mollusc. He is only a close relative of mollusks.

Molluscs have soft bodies, mantles, and generally have shells, which are hidden in the shells for protection, and because the shells hinder movement, they move quite slowly; It is not segmented, and can be divided into three parts: head, feet, and internal organs, and the outer membrane, but some shells are degenerate, such as squid, and there are no shells It can be seen that the description in the question is wrong

So the answer is:

Molluscs have soft bodies, mantles, and generally have shells, which are hidden in the shells for protection, and because the shells hinder movement, they move quite slowly; It is not segmented, and can be divided into three parts: head, foot, and visceral mass, and the outer membrane, but some shells are degenerate, such as squid, and there are no shells It can be seen that the description of the stem is correct

So the answer is: