What do bivalves lack that other classes have?

Unlike all other mollusks, bivalves lack a distinct head with all of its associated organs (tentacles, radula, etc.), and have a pair of shells (called valves), which enclose a laterally compressed soft body, and are usually connected by a hinge and a flexible ligament.

1. What do all bivalves lack?
2. What makes bivalves unique from other mollusks?
3. What is unique about bivalves?
4. What structure is unique to bivalves?
5. Which is not a bivalve?
6. What are the characteristics of cephalopods?
7. Which two structures are missing in bivalves but are present in all other mollusks?
8. What anatomical feature typical of most molluscs and bivalve ancestors is absent in modern bivalves and what accounts for its loss in members of this class?
9. What is the difference between bivalves and brachiopods?
10. What are two characteristics of bivalves?
11. What are the characteristics of molluscs in class Gastropoda?
12. Do bivalves have tentacles?
13. Is bivalve a class of mollusks?
14. How do clams and bivalves vary from other mollusks?

What do all bivalves lack?

Bivalves as a group have no head and they lack some usual molluscan organs like the and the odontophore. They include the clams, oysters, cockles, mussels, scallops, and numerous other families that live in saltwater, as well as a number of families that live in freshwater. The majority are filter feeders.

What makes bivalves unique from other mollusks?

Bivalve mollusks (e.g., clams, oysters, mussels, scallops) have an external covering that is a two-part hinged shell that contains a soft-bodied invertebrate. ... Bivalves even make their own shells.

What is unique about bivalves?

Characteristics of Bivalves

The most important feature of a bivalve is its two shells, called valves. These shells act like a protective armor, guarding the bivalve's soft inner body parts. They can open their shells to move and feed, but at the first hint of a threat, they will rapidly close their shells.

What structure is unique to bivalves?

When the shell is closed, the top part of the hinge ligament is stretched and the lower part is compressed. This means that when the adductor muscles relax, the ligament acts like a spring and the shell opens.

Which is not a bivalve?

The correct option is a) clam. Clams are called bivalves as their shell are also divided into two equal parts and connected by two adductor muscles. b) Octopus -- This option is incorrect because octopus belongs to the cephalopod class but not a bivalve.

What are the characteristics of cephalopods?

All cephalopods have the same basic anatomy. They're made up of a body, a head and a foot. They have a muscular casing called a mantle which contains and protects their organs. They all have arms -- at least eight of them -- that are attached directly to their heads, but only some species also have tentacles.

Which two structures are missing in bivalves but are present in all other mollusks?

In keeping with a largely sedentary and deposit-feeding or suspension-feeding lifestyle, bivalves have lost the head and the radular rasping organ typical of most mollusks.

What anatomical feature typical of most molluscs and bivalve ancestors is absent in modern bivalves and what accounts for its loss in members of this class?

The medial foot is wide. There are no mantle fusions ventrally, and the aerating water current passes through the mantle cavity from front to back, a feature not typical of most modern bivalves.

What is the difference between bivalves and brachiopods?

The key to distinguishing brachiopods from bivalves is determining their lines of symmetry. Bivalves have a plane of symmetry that cuts between their two valves. ... Bivalves are often described as having left and right valves. Brachiopods have a plane of symmetry that cuts across the two valves.

What are two characteristics of bivalves?

bivalve summary

Clams, cockles, mussels, oysters, scallops, and shipworms are bivalves. Most are completely enclosed by the shell, the two valves of which are joined by an elastic ligament, and by two sheets of tissue called the mantle. Bivalves have no head.

What are the characteristics of molluscs in class Gastropoda?

The Class Gastropoda (in Phylum Mollusca) includes the groups pertaining to snails and slugs. The majority of gastropods have a single, usually spirally, coiled shell into which the body can be withdrawn. The shell of these creatures is often what is recovered in a fossil dig.

Do bivalves have tentacles?

Most bivalves are filter feeders, using their gills to capture particulate food such as phytoplankton from the water. ... These primitive bivalves hold on to the substratum with a pair of tentacles at the edge of the mouth, each of which has a single palp, or flap.

Is bivalve a class of mollusks?

Clams, mussels, oysters, and scallops are members to the class Bivalvia (or Pelecypodia). Bivalves have two shells, connected by a flexible ligament, which encase and shield the soft vulnerable parts of the creature.

How do clams and bivalves vary from other mollusks?

The mollusks that have a hinged, two-part shell joined by strong muscles are called bivalves. Clams, Oysters, and Scallops are bivalve mollusks and are a familiar food source. ... While on the other hand Mussels and Oysters attach themselves with a strong thread or cement to solid surfaces.