Mollusks

Question 1

What is a mantle?

Answer 1

a layer of tissue that lies between the **shell **and the body.

Question 2

What is the foot?

Answer 2

the underside used for movement.

Question 3

What are the main features of Molluska?

Answer 3

Huge size range
* **Bilateral **symmetrical
* Unsegmented
* Protostomes
* Complete gut
* Large complex
nephridia (most)
* remove metabolic
wastes

Question 4

What is a radula?

Answer 4

tongue with scraping
teeth used for feeding

Question 5

What is ctenidia?

Answer 5

a respiratory organ or gill in a mollusk with filaments

Question 6

How do ctenia function?

Answer 6

Food particles are trapped in mucus on gills and transported to mouth

Question 7

What type of larvae do mollusks have?

Answer 7

trochophores

Question 8

What are the classes of mollusks?

Answer 8

-Bivalves
-Gastropods(snails and slugs)
Cephalopoda(octopus)
Scaphopoda (Tusk shells)
Aplacophora (marine vermiform molluscs)
Polyplacophora(chittons)

Question 9

What are the characteristics of bivalves?

Answer 9

Two shells (valves)
* ~20,000 species at all depths
* Mostly **sessile filter feeders
* Usually separate sexes
* No “head” or radula**
* Laterally (right-left)
compressed
– held together by a hinge
ligament

Question 10

re the

What is an umbo?

Answer 10

oldest part of the
shell, growth occurs in
concentric rings around it

Question 11

What are siphons used for?

Answer 11

Used to pump water
through the organism
for gas exchange and
filter feeding.
– Sometimes used for jet
propulsion

Question 12

How do bivalves move?

Answer 12

extending the muscular
foot between the
shells.

Question 13

How to scallops move?

Answer 13

clapping their shells
together to create jet
propulsion.

Question 14

What is the largest class of mollusks?

Answer 14

gastropods

Question 15

What are characteristics of gastropods?

Answer 15

Marine, freshwater,
terrestrial.
* Benthic or pelagic
– Not all have shells

Question 16

What is torsion?

Answer 16

a developmental process

Question 17

How does torsion function?

Answer 17

– After veliger settles
– Body twists into permanent** loop**
– **Rearranges organs **and **brings **them together

Question 18

How do herbivore gastropods eat?

Answer 18

most are herbivores
Scrape off algae with Radula

Question 19

How do scavenger gastropods eat?

Answer 19

Tear off pieces with radular teeth

Question 20

How do canivorous gastropods eat?

Answer 20

Modified Radula to drill hole in
shells and eat other mollusks Via chemicals

Question 21

How do snails in the conus family eat

Answer 21

fish, worms, and molluscs.
– Highly modified radula used for prey capture.
– They** secrete** a toxin that paralyzes their prey.
* Some are painful, even lethal, to humans.

Question 22

What are Prosobranchia ?

Answer 22

snails with gills in front of heart

Question 23

What are Opisthobranchia

Answer 23

Snails with gills behind their heart.

Question 24

What is an example of Opisthobranchia

Answer 24

nudibranchs

Question 25

What is an example of Prosobranchia?

Answer 25

Spirally coiled shell

Question 26

What are Pulmonata

Answer 26

land snails and slugs

Question 27

How do Pulmonata reproduce?

Answer 27

-Dart sac secretes calcareous dart (harpoon) * During courtship dart is poked into body wall of the other snail

Question 28

What are the features fo gastropod and bivalve circulation and gas exchange?

Answer 28

**Open** circulatory system * **Heart** with **atria** * **Hemocoel** – body cavity

Question 29

What are Polyplacophora?

Answer 29

chittons: **elongated** with **8 plates**

Question 30

What are Scaphopoda?

Answer 30

tusk shells

Question 31

What are Aplacophora

Answer 31

marine vermiform molluscs

Question 32

What are the main features of cephlapods?

Answer 32

-beak-like jaws surrounded by tentacles of their modified foot. – **Modified foot** is a **funnel **for **expelling water** from the **mantle cavity.** - Ink sacs

Question 33

What are examples of cephalopods?

Answer 33

octopus, squid, nautilus

Question 34

What were early cephlopods like?

Answer 34

Fossils go back to** Cambrian** (570 mya) * The** earliest **had **straight cone**-shaped shells. * **Later** examples had **coiled s**hells similar to** Nautilus**.

Question 35

How does a nautilus shell become buoyant?

Answer 35

made **buoyant** by a series of gas chambers

Question 36

How are cuttlefish shells formed?

Answer 36

a small curved shell, completely **enclosed** by the **mantle**

Question 37

How are squid shells formed?

Answer 37

reduced to a small strip called the pen, which is enclosed in the mantle

Question 38

What is the circulatory system of cephlapods?

Answer 38

closed

Question 39

how many hearts do celphlopods have?

Answer 39

1 systemic 2 branchial

Question 40

What is jet propulsion?

Answer 40

when the animal **takes in water **through its **mantle**. The water is then **pushed **through the **siphon**

Question 41

What are chromatophores?

Answer 41

cells in the skin containing pigment granules allow color change

Question 42

How do cephlopods reproduce?

Answer 42

One arm of **male** is** modified** to **removes** a **spermatophore** from **mantle cavity** and inserts it into female