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What does a mollusk not have?
The most obvious difference between most cephalopods and other mollusks is the apparent lack of a shell. Octopuses do not have shells at all, while squids have a small internal shell.
Do all mollusks have tentacles?
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. Different classes of mollusks have different ways of obtaining food.
Why do mollusks have feet?
Mollusks have a muscular foot used for locomotion and anchorage that varies in shape and function, depending on the type of mollusk under study. In shelled mollusks, this foot is usually the same size as the opening of the shell. The foot is a retractable as well as an extendable organ.
Do clams have jointed legs?
Many invertebrates protect their soft bodies with a hard outer casing called an exoskeleton. These animals are part of a group of invertebrates called arthropods, meaning “jointed legs.” Some mollusks, such as snails and clams, have a hard shell that they can hide in when danger threatens. …
Do all mollusks have a foot?
All mollusks have a thin layer of tissue called a mantle which covers their internal organs. The mantle produces the mollusk’s shell. Clams, oysters, snails, and octopuses are all mollusks. Most mollusks move with a muscular structure called a foot.
How many legs do molluscs have?
Molluscs don’t have legs, though some have flexible tentacles for sensing their environment or grabbing things. Most mollusc species grow a hard shell for protection, but their shell grows in only one or two pieces.
Do all molluscs have a foot?
Do all mollusks have foot?
What is foot in Mollusca?
In muscle: Mollusks. … highly muscular organ called the foot, through which muscle fibres run in all directions. The foot of a gastropod is a flat structure used for crawling. Waves of muscular contraction travel along its length, moving the animal slowly over the ground.
Do mollusks have jointed legs?
Mollusks are the soft-bodied invertebrates with one or two shells, whereas arthropods are the invertebrates with segmented bodies, jointed legs and appendages. That is; unlike arthropods, some mollusk species have a muscular foot for locomotion. In contrast, arthropods like insects have wings to fly.
What does the foot of Mollusca consist of?
In shelled mollusks, this foot is usually the same size as the opening of the shell. The foot is a retractable as well as an extendable organ. The foot is the ventral-most organ, whereas the mantle is the limiting dorsal organ.
What are mollusks classified as animals?
snails, clams, squids and octopodes Mollusks are a large group of invertebrate animals. Mollusks have soft bodies, and their bodies are not divided into rings like the segmented worms called annelids. Most mollusk species only live in the ocean, but some live in freshwater or on land. How are mollusks classified which phylum?
What are the main characteristics of Mollusca?
Main characteristics of Mollusca : Unsegmented soft body with bilateral symmetry. Presence of an internal or external shell. A toothed tongue (made mostly of chitin) called the radula.
What are the parts of the mollusk body plan?
The four parts of the mollusk body plan are the foot (used for locomotion), mantle (which secretes the shell), shell (which covers), and viceral mass (contains heart and organs). What are the characteristics of molluscs in class Gastropoda?
What are the characteristics of gastropods?
Gastropoda. The Class Gastropoda includes the snails and slugs. Most gastropods have a single, usually spirally coiled shell into which the body can be withdrawn, but the shell is lost or reduced some important groups.