Lesson 22a

Question 1

What is phylum Mollusca?

Answer 1

The Molluscs

Question 2

Name 6 characteristics of animals in phylum Mollusca (molluscs)…

Answer 2

A. Primarily marine animals, with some found in freshwater or on land
B. Bilateral symmetry
C. Soft bodies
D. Muscular foot used for movement and anchoring
E. Visceral mass contains vital organs
F. Mantle: skin-like organ covering the visceral mass, it secrets their shell (if they have one)

Question 3

What is class Bivalvia?

What is in class Bivalvia?

What is their main characteristic?

Answer 3

The bivalves!

Clams, oysters, mussels, scallops, and geoducks

2 shells connected by a hinge

Question 4

What is Nacre?

Answer 4

It is secreted in thin layers, coating irritants or parasites inside the shell of molluscs, creating a pearl over time

Question 5

Explain the structure of Bivalves… (7things)

Answer 5

1. Hinge teeth and ligaments align the two shells
2. Adductor muscles are strong muscles holding the shells together
3. Umbo: the small bulge on the two shells near the hinge
4. Mantel: specialized tissue that lines the inside of the shell and secretes new shell material
5. Visceral mass: located between the two sides of the mantle and
   contains most of the organism’s organs
6. Muscular foot is found inside the shells and used for movement
7. Gills are found on each side of the mantle
8. Siphon: water moves in (incurrent siphon) and out (excurrent siphon) of the animal through two siphons found at the back end of the animal

Question 6

How do Bivalves eat?

Answer 6

They are suspension feeders, filtering water and feeding on food suspended in water

                 (1) Dead organic particles suspended in the water stick to a thin mucous layer of the gills
                 (2) Cilia on the gills move the food to the mouth opening where it’s ingested

Question 7

Explain Bivalves circulatory system if they have one…

Answer 7

They have an open circulatory system with a heart but no blood vessels

Question 8

Explain Bivalves nervous system if they have one…

Answer 8

Their nervous system is made up of 3 pairs of ganglia connected by nerves that extend to the foot and body

Question 9

How do Bivalves reproduce?

Answer 9

They reproduce sexually

a) Sperm leave the male through the excurrent siphon and enter the female through her incurrent siphon
b) Eggs are on the female’s gills, where they’re fertilized

Question 10

Lesson 22a summary…

Answer 10

file:///C:/Users/trgan/Sync/LisA%20school/Lesson%2022-%20Phylum%20Mollusca%20summary.mp4