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BIOL 205 > Mollusca > Flashcards

Mollusca Flashcards

1
Q

Name the 9 traits of Phylum Mollusca

A
  1. Bilateral or asymmetrical protosotomes. They’re unsegmented
  2. Complete gut, regionally specialized
  3. Metanephriudia - an excretory system
  4. They have a mantle - a growth of tissue sheet away from the main body
  5. Mantle with shell glands - ectodermally derived
  6. Radula - physically breaks down large food to smaller structures
  7. Muscular ventral foot
  8. Reduced coelom
  9. Open circulatory system - has a heart with 3 chambers
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2
Q

What are the 6 synapomorphies of Mollusca?

A
  1. Mantle
  2. Mantle with shell glands
  3. Radula
  4. Muscular ventral foot
  5. Reduced coelom
  6. Open circulatory system
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3
Q

Major subgroup of Mollusca - Aplacophora

A

Shell-less, worm-shaped molluscs that are encased with spicules (CaCO3, or other hard organic materials). Live in sediment

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4
Q

Major subgroup of Mollusca - Monoplacophora

A

Has one shell and a paired gill in their donut-shaped mantle. Muscles are segmentally-like arranged. Mostly extinct

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5
Q

Major subgroup of Mollusca - Polyplacophora

A

Chitons. Have many shells. Locks itself onto substrates and uses its radula to feed.

Can roll up to protect their soft ventral side

Looks segmented because of overlapping shells

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6
Q

Major subgroup of Mollusca - Scaphopoda

A

Tube-shaped shell. The smaller hole is the oldest, and the larger hole is younger. Gills are lost

Selective deposit feeders. Tentacles come out of the larger hole

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7
Q

Major subgroup of Mollusca - Bivalvia

A

Have gills to move water and collect food

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8
Q

Major subgroup of Mollusca - Cephalopoda

A

Sophisticated vision and huge brain

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9
Q

Gastropoda

A

Only one shell that’s spiralling one direction. Asymmetry in the adult phase

Edge of the mantle had shell glands that secretes the shell

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10
Q

Pneumostome

A

A hole where air enters/exits. Can open/close “lung”

There is a tube that comes out of the pneumostome to defecate

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11
Q

Operculum

A

Closes up the hole when the snail hides in its shell

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12
Q

Gills

A

Protected inside the mantle cavity and is enveloped in epidermis

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13
Q

Ventral foot

A

Used for locomotion

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14
Q

Torsion

A

Synapomorphy for the Gastropod

During development, the mantle starts posteriorly, but moves to the anterior so the snail can get their head in first in the shell to protect itself from predators

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15
Q

5 structures in the mantle cavity

A
  1. Ctenidia - gills; used for gas exchange because of its large SA
  2. Anus
  3. Gonophores
  4. Nephridiopores - a part of the nephridium (excretory system)
  5. Osphradia - chemoreceptor that tests incoming water for deposits and food particles. Also linked with the respiratory organ
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16
Q

Where does primary digestion occur

A

Extracellularly; stomach (unsure)

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17
Q

Where does final digestion occur

A

Digestive gland and intestine

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18
Q

Salivary gland

A

Secretes mucus

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19
Q

Pharynx

A

Located at the back of the buccal capsule

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20
Q

Buccal capsule

A

Cavity behind the mouth

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21
Q

Stomach

A

Breaks down food enzymatically

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22
Q

Radula

A

Made of chitin. Basically a tape-shaped piece of sandpaper

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23
Q

Odontophore

A

Part of the feeding mechanism and is the cartilage that underlies and supports the radula

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24
Q

Enzymatic gland

A

Secretes enzymes that help break food down

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25
Q

Circulation and gas exchange. Open or closed?

A

Internal transport. Way to create SA to make sure everything in the body is supplied with nutrients

They have an open circulatory system and have hemolymph that bathe the organs. Their capillaries are useful because blood cells are enclosed in a network of tubes that allow every cell to interact with the tube

26
Q

Nervous system of Gastropoda

A

Has pedal nerve cords (ladder-like)

Has a nerve ring - circumenteric nerve ring

Had a cerebral gangion - brain

27
Q

What tissue layer produces the shell?

A

Ectodermally-derived glands

28
Q

Nacreous layer

A

Smooth area of shell (CaCO3). The mantle gland secretes the nacreous layer

29
Q

Prismatic layer

A

Chalky layer (CaO3)

30
Q

Periostracum

A

Outer-most shell. It’s an organic layer

31
Q

Conchin

A

Proteinaceous material that covers the shell

32
Q

Prismatic gland

A

Secretes the prismatic layer

33
Q

Periostracum gland

A

Secretes the periostracum

34
Q

How are pearls formed in clams?

A

A sand grain gets stuck in the mantle gland and the nacreous layer will build around it

35
Q

Circulation, excretion, and gas exchange

A

To fully understand the entirety of it, view the image on the notes

36
Q

Hinge ligament

A

On bivalves, specifically clams, that is robust and elastic. It allows the shell to spring open. It’s an agonistic muscle to the adductor muscles

37
Q

Are clams (bivalves) infaunal or epifaunal?

A

Infaunal because they bury themselves in sediment

38
Q

Are mussels (bivalves) infaunal or epifaunal?

A

Epifaunal because they live on top of rocks

39
Q

Byssal gland

A

On mussels, which secretes adhesive threads so it can coat the foot and attach to rocks

40
Q

Mussels’s reduced foot function

A

It secretes glue so it can attach to the rock

41
Q

Byssal threads of mussels

A

Very strong and allows the mussel to attach to rocks

42
Q

Crystalline style sac of bivalves and how it sharpens

A

Has cilia in it that turns the crystalline style. The crystalline style then turns along its axis and gets sharpened by rubbing against the gastric shield

Chemically breaks down food(??)

43
Q

Chromatophore muscles relaxed

A

When relaxed, the muscles are long and the chromatophore is small

44
Q

Chromatophore muscles contracted

A

When contracted, it spreads out the chromatopohore and the muscles shorten

45
Q

Squid eye

A

Its pupil stays horizontal, no matter the orientation

46
Q

Chromatophores

A

Allows them to change colors for camouflage in their surroundings

47
Q

Mouth of squid

A

Associated with the beak. Beak is behind the radula that rips and shreds food. The salivary glands has toxins

48
Q

Squid siphon (modified foot)

A

Where H2O exits mantle cavity at a high velocity - allows jet propulsion

49
Q

How many tentacles do squids have and what are the function of suckers?

A

They have 2 tentacles and suckers are present on each of them. They are sensitive chemoreceptors for touch

50
Q

Squid’s muscular mantle - function of radial and circular muscle

A

Radial muscle - when it contracts, it sucks in H2O

Circular muscle - when it contracts, H2O leaves

51
Q

Squid fin

A

Stabilized animal to prevel roll

52
Q

Squid pen

A

Provides structural integrity along longitudinal axis of the visceral hump

53
Q

Types of reproduction in Mollusca

A

Sexual - direct, indirect, and mixed

Some are dioecious, hermaphroditic, and adelphophagio (which is the consumption of one embryo by another in utero)

54
Q

Why do gastropods detort?

A

Ancestors had the developmental pattern of torsion, but the lack of shell relaxes it and goes back to posterior

55
Q

3 types of Opisthobranchia in gastropods

A

Aeolid nudibranch

Apylsiomorpha

Dorid nudibranch

56
Q

Kleptoplasty

A

It means to steal the chloroplast of its food. Allows opisthobranchs to be a plant-like gastropod

57
Q

Kleptocnidae

A

It means to steal the cnidae of its food. Stores it in its cnidosac and fires when threatened

58
Q

Characteristics of aplysiomorpha sea slug

A

Mouth
Gut
Mantle cavity
Gill, which is enveloped by epidermis
Anus

59
Q

Characteristics of dorid nudibranch sea slug

A

Mouth
Gut
Branchial plume - gill
Anus

60
Q

Characteristics of aeolid nudibranch sea slug

A

Has no gills
Has no mantle cavity
Has a cephalic tentacle
Has rhinopores
Cnidosac - has a sac of nematocysts that it stole from the anemone it are. Reflects the characteristic of kleptocnidae
Cerata (p.); ceratum (s.) - creating area fro respiration. Each one has a branch of the digestive tract

61
Q
A

BIOL 205 (13 decks)

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