Phylum Mollusca, Class Bivalvia Flashcards

Questions and Answers

What is Phylum Mollusca?

Soft-bodied animals with an internal shell (correct)

Soft-bodied animals with an external shell (correct)

Soft-bodied animals that may or may not have a shell (correct)

Hard-bodied animals with an external shell

What organisms are classified under Class Bivalvia?

Clams, scallops, mussels, and oysters

What is a true coelom?

A body cavity completely lined with tissue derived from mesoderm

An open circulatory system allows blood to flow entirely within blood vessels.

False Signup and view all the answers

What is a complete digestive system?

An animal has a mouth and anus; food travels one way Signup and view all the answers

Many freshwater clams have a ___ larval stage that attaches to the gills of fish and lives as a parasite for a few weeks.

glochidium Signup and view all the answers

What are zygotes?

A fertilized egg Signup and view all the answers

Bivalves have two shells (valves) that are laterally compressed and dorsally hinged, known as ___.

valves Signup and view all the answers

What is the function of siphons in bivalves?

Used for pumping water Signup and view all the answers

What does the hinge ligament do?

Joins the two valves at the dorsal end Signup and view all the answers

The shells are hinged at one end; the hinge is known as the ___.

umbo Signup and view all the answers

What is the function of the anterior adductor muscle?

Keeps the clam shut, closest muscle to the umbo Signup and view all the answers

What is the posterior adductor muscle?

Furthest muscle from the umbo, helps keep the clam shut Signup and view all the answers

What is a pallial line?

A line on the inside of each valve marking the zone of attachment Signup and view all the answers

What do ostia do?

Holes that return hemolymph to the heart in arthropods Signup and view all the answers

What is the role of the ventricle in the heart?

Bottom portion of the heart, thicker walled and larger Signup and view all the answers

What is the auricle in the heart?

One of the two chambers of the heart which receives blood from the veins Signup and view all the answers

What is the anterior aorta?

Carries blood from heart to anterior body regions and head Signup and view all the answers

What structure receives incoming water in bivalves?

Incurrent aperture Signup and view all the answers

What does the excurrent aperture do?

Water exits Signup and view all the answers

What is the nacreous layer?

A CaCO3 layer over protein secreted throughout the mollusks' life span Signup and view all the answers

What is the visceral mass?

Area beneath the mantle that contains the internal organs Signup and view all the answers

What are gill lamellae?

Structures that make up a gill filament and contain a capillary bed Signup and view all the answers

What are water tubes in bivalves?

Large empty spaces in the gill that allow water to flow over the surface Signup and view all the answers

What is the coelomic cavity?

Area between the body wall and digestive tract Signup and view all the answers

Study Notes

Phylum Mollusca

Soft-bodied animals with internal or external shells.

Class Bivalvia

Includes clams, scallops, mussels, and oysters.
Characterized by two shells (valves) hinged at the umbo, lacking a radula.

True Coelom

A body cavity fully lined with a tissue derived from the mesoderm.

Open Circulatory System

Blood flows out of vessels and into body cavities, allowing direct contact with cells.

Complete Digestive System

Animals possess both a mouth and anus, allowing food to travel in one direction.

Glochidium

A specialized larval stage in many freshwater clams that attaches to fish gills and lives as a parasite temporarily.

Zygotes

Fertilized eggs resulting from the union of male and female gametes.

Valves

Bivalves have two laterally compressed shells that are dorsally hinged.

Siphons

Structures used for pumping water in and out of the body.

Hinge Ligament

Connects the two valves at the dorsal end.

Umbo

The hinged end of the bivalve shell.

Anterior Adductor

The muscle closest to the umbo aiding in keeping the clam shut.

Posterior Adductor

The muscle furthest from the umbo, also assists in closing the clam.

Pallial Line

A line on the inner side of each valve indicating muscle attachment around the mantle margin.

Incurrent Aperture

The opening that receives incoming water for feeding and respiration.

Excurrent Aperture

The opening through which water exits the bivalve.

Ventricle

The thicker and larger lower chamber of the heart that pumps blood.

Auricle

The upper chamber of the heart that receives blood from the veins.

Anterior Aorta

Carries blood from the heart to the anterior body regions and head.

Posterior Aorta

Delivers hemolymph to the rectum and mantle region.

Nacreous Layer

A layer of calcium carbonate over protein, secreted throughout the mollusk's life. It's utilized in jewelry and can form pearls when irritants enter the body.

Pericardial Sac

The membrane covering the heart's surface.

Visceral Mass

The area beneath the mantle containing vital internal organs of the mollusk.

Gill Lamella

Comprises one of the numerous sheet-like structures in gills containing a capillary bed.

Water Tubes

Large empty spaces in the gills that help in water flow over the gill surfaces.

Coelomic Cavity

The space between the body wall and the digestive tract.

Reproduction in Clams

Specific details on reproductive processes in clams are not provided in the notes.

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Description

Test your knowledge about Phylum Mollusca and its Class Bivalvia with these flashcards. Learn about their defining characteristics, such as having two shells, and the unique features that distinguish them from other mollusks.