13. Mollusks Flashcards Preview

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Flashcards in 13. Mollusks Deck (29):
0

Mollusks are part of which subgroup?

Lophotrochozoa (protosomes)

1

How large is the animal group of mollusk?

Second largest after arthropods

2

Mollusks - diversity?

Highly diverse in response to environment
- Terrestrial or aquatic
- Different morphology, mode of nutrition, reproduction

3

Mollusca - body shapes?

Bilaterally symmetrical, triploblastic, coelomate protostomes

4

Mollusca are ..... larvae

Trochophore larvae (marine mollusks)

5

Major groups of mollusca?

Polyplacophora
Gastropoda
Bivalvia
Cephalopoda

6

Mollusk body plan?

- Foot at bottom
- Mantle
- Visceral mass
Contains gills (if aquatic) or acts as lung (if terrestrial)

7

Polyplacophora means....

Many plates

8

Characteristics of polyplacophora?

Segmented shell (8 overlapping plates)
Multiple gills

9

Polyplacophora - feeding?

Omnivorous - radula scrapes algae & bryozoans

10

Characteristics of bivalvia?

- Reduction of head
- Hinged shell
- Enlargement of foot
- Mantle cavity modified by siphons
- Enlargement of gill
- Relatively sessile
- Filter feeders
- Broadcast spawners

11

Siphons?

Extensions of posterior mantle
Water flows in mantle cavity and then across gills that act as filters for food

12

Bivalvia close shell...

With their large adductor muscles

13

Mantle of bivalvia is lined with...

Eyes - to detect motion and light

14

How large is the gastropoda group?

Most diverse group of mollusks

15

Gastropoda - habitat?

Terrestrial or aquatic

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Gastropoda - feeding?

Herbivores, predators, scavengers

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Gastropoda - reproduction?

- Internal or external fertilization
- Either dioecious or hermaphroditic, but can produce only sperm or eggs at one time

18

Some cool stuff gastropods do with their body?

- Torsion (twisting of body - 180 degrees rotation of visceral mass, mantle cavity, anus moved over head)
- Coiling of visceral mass

19

Characteristic of land snails?

Eyes on tips of tentacles

20

Characteristic of cone snail?

Radula modified into toxic harpoon (peptide toxins)

21

Some gastropods have nudibranchs which allows....

Secondary de-torsion

22

Some gastropods prey on tentacles of ......

Cnidarian polyps and re-used the cnidocytes

23

Body characteristics of cephalopoda?

- Subdivided foot (arms, tentacles)
- Enlarged head, reduced shell)

24

Cephalopods - feeding?

Predators

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As predators, cephalopods have...

- Excellent vision
- Complex behaviour (visual communication with colour and texture, cryptic colouration)
- Ink sac for defense
- Closed circulatory system
- Mantle & siphon used for jet propulsion
- Arms with suckers &/or hooks - some have 2 elongated tentacles

26

Cephalopod reproduction?

Separate sexes!! (with elaborate courtship)
- Internal fertilization (males transfer sperm via specialized arm - hectocotylus)
- Females die after laying eggs (or after eggs hatch)
- NO TROCHOPHORE LARVA

27

Nautilus - example of a cephalopod. Characteristics?

- 80-90 arms
- Regulate buoyancy with gases in chambered shell
- Only extant shelled cephalopod

28

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