What is the function of shell in molluscs?

What is the function of shell in molluscs?

In nature, mollusk shells have a role in protecting the soft body of the mollusk from predators and from the external environment, and the shells consist mainly of calcium carbonate and small amounts of organic matrices. Organic matrices in mollusk shells are thought to play key roles in shell formation.

What is an advantage of having an external shell?

The many possible benefits of shell loss include weight reduction (in pelagic sea slugs), coping with mineral deficiency (in land slugs), streamlining (in swimming or burrowing species), an ability to crawl into tight spaces (in slugs and octopi), a more distensible body (in forms that eat large prey or swim by jet …

Do mollusks have a hard external shell?

Mollusks have a hard outer shell. There is a layer of tissue called the mantle between the shell and the body. Most mollusks have tentacles for feeding and sensing, and many have a muscular foot. Mollusks also have a coelom, a complete digestive system, and specialized organs for excretion.

What are the external features of molluscs?

Characteristic Features of Phylum Mollusca

• They are bilaterally symmetrical.
• They are triploblastic, which three layers.
• They show organ system grade of organisation.
• The body is soft and unsegmented.
• Body is divisible into three regions – head, a visceral mass, and ventral foot.
• Body is covered by a mantle and shell.

What are the two portions of a mollusk shell called?

A bivalve shell is part of the body, the exoskeleton or shell, of a bivalve mollusk. In life, the shell of this class of mollusks is composed of two hinged parts or valves. Bivalves are very common in essentially all aquatic locales, including saltwater, brackish water, and freshwater.

What are the disadvantages of shell structures?

THE DISADVANTAGE OF SHELL STRUCTURE IS THEIR COST. THE SHELL STRUCTURE IS MORE EXPENSIVE DUE TO CONSIDERABLE LABOUR REQUIRED TO CONSTRUCT THE CENTERING ON WHICH THE SHELL IS CAST.

What is a disadvantage to having a shell?

Let’s move on to my favorite evolutionary “disadvantage” of having a shell. The ribcage of most vertebrates assists in that animal’s respiration. But as an animal’s ribcage becomes fused, its ribcage loses the ability to move and consequentially aid in breathing.

What structures do all molluscs have in common?

Some common features are :

• Unsegmented soft body with bilateral symmetry.
• Presence of an internal or external shell.
• A toothed tongue (made mostly of chitin) called the radula.
• A mantle which is a fold in the body wall that lines the shell.
• Muscular foot (and/or tentacles in some).

What makes the shell of a mollusk unique?

Two unique features of mollusks are the mantle and radula (see Figure above). The mantle is a layer of tissue that lies between the shell and the body. It secretes calcium carbonate to form the shell. It forms a cavity, called the mantle cavity, between the mantle and the body.

What kind of digestive system does a mollusk have?

Mollusks have a hard outer shell. There is a layer of tissue called the mantle between the shell and the body. Most mollusks have tentacles for feeding and sensing, and many have a muscular foot. Mollusks also have a coelom, a complete digestive system, and specialized organs for excretion. The majority of mollusks live in the ocean.

What are the physical features of a Mollusca?

This group displays a broad range of morphological features such as a muscular foot, a mantle and visceral mass containing internal organs. Calcium carbonate secretes from the mantle and forms outer calciferous body shell in most of the mollusks.

Are there any mollusks that are good for humans?

Many molluscans are not good for human’s lives. Some cause diseases or acts as pests like the snails and slugs. Generally, the hard calciferous shells of mollusks are used to build awesome jewellery pieces. Some mollusks such as bivalves and gastropods produce valuable pearls.

Why do mollusks have a hard outer shell?

A hard outer shell has been an invaluable asset to many a mollusk—some successful extant lineages may owe their survival to this feature. Mollusk shells have even influenced the fate and evolution of non-mollusks, of which hermit crabs may be the best example.

Why are molluscan shells important to human life?

They play an important role in the lives of humans because they are the source of food for many people as well as jewellery. Many molluscans are not good for human’s lives. Some cause diseases or acts as pests like the snails and slugs. Generally, the hard calciferous shells of mollusks are used to build awesome jewellery pieces.

Mollusks have a hard outer shell. There is a layer of tissue called the mantle between the shell and the body. Most mollusks have tentacles for feeding and sensing, and many have a muscular foot. Mollusks also have a coelom, a complete digestive system, and specialized organs for excretion. The majority of mollusks live in the ocean.

This group displays a broad range of morphological features such as a muscular foot, a mantle and visceral mass containing internal organs. Calcium carbonate secretes from the mantle and forms outer calciferous body shell in most of the mollusks.