Phylum Mollusca

Question 1

What are the general characteristics of molluscs?

Answer 1

Have 3 cell layers, a coelom, a brain and have a body divided into three regions the head/foot the visceral mass and the mantle

Question 2

What is a coelom?

Answer 2

It’s a body cavity, or space within the mesoderm. It functions as a hydrostatic skeleton and provides a space for internal organs to be suspended by mesenteries

Question 3

What is a coelom?

Answer 3

It’s a body cavity, or space within the mesoderm. It functions as a hydrostatic skeleton and provides a space for internal organs to be suspended by mesenteries

Question 4

What is in the head and what’s the functions?

Answer 4

Have a mouth, appendages and sensory organs. Have a radula(a toothed tongue). It is used to scrape off bits of algae or organic material off rocks or tear at plants.

Question 5

What is the functions of the foot?

Answer 5

For crawling(slugs), for burrowing and locomotion(clams), into tentacles and arms with suckers(squid) for capturing prey, into a siphon for jet propulsion(octopus)

Question 6

What’s visceral mass?

Answer 6

Soft body portion containing all internal organs

Question 7

What’s a mantle?

Answer 7

Tissue that surrounds and protects the internal organs; cavity where gills or lungs are located

Question 8

What’s class bivalvia?

Answer 8

Clams, oysters,etc.. the shell of a bivalve is composed of calcium carbonate and consists of two similar parts called valves.

Question 9

What are the function of adductor muscles?

Answer 9

Keeps valves closed. There are no apposing muscles for opening the shell.

Question 10

What’s the function of muscular foot?

Answer 10

For locomotion and burrowing in sand or mud.

Question 11

How does ingestion occur in clams?

Answer 11

The incurrent siphon contracts bringing in H2o and plankton, through the mantle cavity to gills.

Question 12

How does digestion occur in clams?

Answer 12

Food moves down esophagus into the stomach.

Digestive enzymes are produced and secrete into the stomach and chemically break down foods.

Digested nutrients leave the stomach and enter the intestine where they diffuse across the gastrodermis.

Question 13

How does elimination occur in clams?

Answer 13

Undigested food wastes pass into the rectum and out the anus and into the mantle cavity, where they exit via the excurrent siphon.

Question 14

What type of circulatory system do clams have?

Answer 14

Open circulatory system.

Consists of a heart, blood vessels and sinuses.

Question 15

How do clams circulate?

Answer 15

Nutrients and O2 in the blood are pumped by the heart, through blood vessels, and into sinuses.

Body tissues and organs ate bathed in blood of the sinus and there is an exchange of nutrients, N-wastes and gases.

Question 16

How do clams go through respiration?

Answer 16

Water and O2 enter through the incurrent siphon and travel over the gills.

O2 is removed by the gills and diffuses into blood vessels and CO2 diffuses out of the blood into the gills and out into water, exits via the excurrent siphon.

Question 17

How do clams go through excretion?

Answer 17

2 kidneys filter N-wastes and excess h2o from the blood and fluid from the coelomic cavity surrounding the heart.

waste is deposited into the mantle cavity and leaves via excurrent siphon.

Question 18

What are a clams nervous system?

Answer 18

They have a less complex nervous system then most other molluscs.

Have no brain; the nervous system consists of a nerve network and a series of paired ganglia.

Question 19

What are ganglia?

Answer 19

A cluster of nerve cell bodies.

Question 20

How to clams move?

Answer 20

The pressure of the fluid in the coelom and the action of the surrounding muscles are used to change an organisms shape and make them move.

Question 21

How do clams reproduce?

Answer 21

They are dioecious (separate sexes)

They produce many gametes which are released into the water from the excurrent siphon.

External fertilization produces a zygote which develops into a free swimming larvae, and into a clam.

Question 22

What are some characteristics of Cephalopods?

Answer 22

Highly advanced marine animals.

Have arms and tentacles (8 or 10 in most forms and 90 in Nautilus)

Have highly developed senses and brains, expect for nautilus (has acute vision).

Most have colour pigment cells (chromatophores) for camouflage.
Can also change texture of skin using papillae.

Question 23

What type of circulatory system do cephalopods have?

Answer 23

Have 3 hearts and a closed circulatory system.

Blood is confined to the heart and blood vessels at all times.

Question 24

What is jet propulsion in cephalopods?

Answer 24

The typical way of swimming fast.

Water is sucked in under the mantle collar and then squeezed out the siphon.

Question 25

What are more characteristics of cephalopods?

Answer 25

Squids have a reduced internal shell called a pen, It offers support to the mantle.

Octopuses lack a shell.

Cephalopods also have a radula used for feeding purposes.

Have jaws for grasping and tearing prey.