What are the molluscs? What are the common mollusks

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There are also river mussels, snails, slugs (also called flyflies, commonly known as slugs) reference: mollusks are also called shellfish because they often have shells in their bodies. One shell (such as snails, etc.), two (such as mussels, etc.) or more (such as stone turtles, etc.), but there are also those that degenerate into inner shells (such as squid, etc.) or no shells (such as dragon hairpins and crescent shells).

Molluscas have some of the same characteristics as annelids: secondary body cavities, posterior renal ducts, developing trochal wheel larval stages, etc., so it is thought that mollusks evolved from annelids and developed towards a less active lifestyle. There are many kinds of molluscs, it is the second largest group in the animal kingdom, with 130,000 species of molluscs recorded, widely distributed, and can be divided into 7 classes:

1) Venetian (such as new disc shells, etc.), (2) Plateless (such as dragon hairpins, etc.), (3) Polyplatedae often lose sweet juice imitation with wet treasure splashing (such as hairy stone turtles, etc.), (4) Gastropoda (such as round snails, nudibranchs, snails, etc.), (5) Dignapods (such as horned shells, etc.), (6) Petal gill (such as river mussels, etc.), (7) Cephalopods (such as squid, etc.).

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Birds: Steller's sea eagle, emperor penguin, grey magpie, red-crowned crane.

Fish: great white shark, Chinese sturgeon, branch seahorse, sunfish.

Molluscs: scallops, squid, snails, slugs.

Arthropods: two-horned rhinoceros beetle, yellow horse, red sea crab, Jiwei shrimp.

Molluscas include snails, octopuses, earthworms, mussels, snails, cockles, and squid.

Oysters, scallops, mussels.

Nautilus, hydra, coral, razor clams, abalone, jellyfish, nudibranchs.

Sea anemones, tube worms, etc. Molluscs, also known as shellfish, are the collective name of molluscs and are the largest group of animals except arthropods, with about 100,000 species.

The main characteristics of mollusks are: soft body surface with mantle, mostly with shells; The locomotor organ is the foot. The morphological structure of mollusks varies greatly, but the basic structure is the same.

The body is soft and has a hard shell in which the body is hidden for protection, and they are quite slow to move due to the fact that the hard shell hinders movement. It is not segmented, it can be divided into three parts: head, foot, and visceral mass, and the outer membrane often secretes shells. The foot is shaped like an axe and has two shells, like an oyster.

Common mollusks are snails, snails, mussels, cockles, squid, octopus, etc.

1. Snail: It is the most common mollusk on land, and the snail is an animal that includes many different families and genera.

2. River mussel: It is a general term for a group of animals in the mollusk phylum mussel family, which is called mussel shell and crooked child in some places.

3. Octopus: It is a temperate mollusk, living underwater, adapting to the water temperature can not be lower than 7, and the environment with low salinity will die.

Mollusks are the second gate in the animal kingdom.

The body is soft, generally symmetrical from left to right, and some species have various peculiar forms due to twisting and bending.

Usually shelled, asegmental, with fleshy feet or wrists, and degenerated feet. The outer layer** is folded from the back into a so-called coat, which surrounds the body and secretes a calcareous shell for protection.

The gills for breathing are found in the cavity between the coat and the body. It is distributed all over the land and water. Including bineuroids (e.g., turtles), gastropods (e.g., abalone, snails), pods (e.g., horned shellfish), valvegill (e.g., cockles, oysters), cephalopods (e.g., squid, nautilus), etc.

The mollusks involved in citrus pests are mainly gastropods.

Molluscs include gastropods that are familiar to people in life, such as snails, snails, slugs; bivalves such as mussels, cockles, etc.; cephalopod squid (cuttlefish), octopus, etc.; and multi-plate turtles attached to coastal intertidal rocks. They are very different in morphology, such as their systems are either symmetrical or asymmetrical; body surface is either shelled or shellless; The shell or hail orange is one or two or more pieces.

Molluscs can be divided into 8 classes: Monophyta, Polyplate, Aplate, Gastropoda, Bival, Dipoda, and Cephalopod.

Molluscs:

1. The clam is a round clam mollusk, which is the longest-lived mollusk in the world. Because they lived in the Ming Dynasty in China, they were called Ming clams. Ming grew up at the bottom of the sea in Iceland.

The texture of the shell indicates that it is now 507 years old. Bright shells only grow in the summer. When the sea water is warm and there is enough food, a layer of grain about a millimeter thick grows on the bright shells every year.

This is precisely because the thickness of each texture on the open shell depends on the environment at the time.

2. The nautilus is the oldest mollusk in the world, having undergone hundreds of millions of years of evolution on Earth, but its shape and habits have hardly changed. It is known as "living fossils" and the study of marine and biological evolution and paleontology is of great value. The nautilus has a curly, pearly shell.

The shells are smooth and curly. The maximum shell length can be up to centimeters, but the shell length of adult nautilus snails is generally no more than 20 centimeters. In the Ordovician oceans, the nautilus can be called the apex predator.

Its length can reach up to 11 meters.

3. The naked sea butterfly is an ocean angel that lives at a depth of 350 meters in the Arctic Ocean and the Southern Ocean. It is also the most beautiful mollusk in the world. The total length is about 2 cm to 3 cm.

This is a planktonic mollusk. Hermaphroditic and lives under the ice of the Arctic, Antarctica, and other cold waters. The whole body is transparent, also known as "sea angel", "ice elf" and so on.

A good name for a sea angel may be associated with a pair of wing-like organs. When its wings swim in the sea, its small wings look like angel's wings.

4. King squid usually lives in deep-sea areas and is the largest known aquatic mollusk in the world. In general, juvenile king squid have a body length of 8-10 meters, and adult king squid can reach a body length of up to 20 meters. Their eyes are surprisingly large, about 35 centimeters in diameter; The diameter of the suction cup is also more than 8 cm.

King squid lives in the deep sea. It rests in the deep sea during the day and swims to the shallow sea at night to feed. It feeds on fish and can catch prey in the dark oceans.

5. Boat borers, the ugliest mollusks in the world. The boat borer is a marine creature that can perforate wood. When it attaches to wood, it can dig a conical hole in the wood and invade the interior of the wood.

This type of hole has only one hole that is connected to the outside world. If the external conditions are unfavorable or attacked by other marine organisms, the drilling rig will drill into the inner hole of the wood and secrete calcium to block the hole to resist the attack of other organisms.