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BIOL 205 > Mollusca > Flashcards

Mollusca Flashcards

(61 cards)

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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
Circulation and gas exchange. Open or closed?
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
Nervous system of Gastropoda
Has pedal nerve cords (ladder-like) Has a nerve ring - circumenteric nerve ring Had a cerebral gangion - brain
27
What tissue layer produces the shell?
Ectodermally-derived glands
28
Nacreous layer
Smooth area of shell (CaCO3). The mantle gland secretes the nacreous layer
29
Prismatic layer
Chalky layer (CaO3)
30
Periostracum
Outer-most shell. It's an organic layer
31
Conchin
Proteinaceous material that covers the shell
32
Prismatic gland
Secretes the prismatic layer
33
Periostracum gland
Secretes the periostracum
34
How are pearls formed in clams?
A sand grain gets stuck in the mantle gland and the nacreous layer will build around it
35
Circulation, excretion, and gas exchange
To fully understand the entirety of it, view the image on the notes
36
Hinge ligament
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
Are clams (bivalves) infaunal or epifaunal?
Infaunal because they bury themselves in sediment
38
Are mussels (bivalves) infaunal or epifaunal?
Epifaunal because they live on top of rocks
39
Byssal gland
On mussels, which secretes adhesive threads so it can coat the foot and attach to rocks
40
Mussels's reduced foot function
It secretes glue so it can attach to the rock
41
Byssal threads of mussels
Very strong and allows the mussel to attach to rocks
42
Crystalline style sac of bivalves and how it sharpens
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
Chromatophore muscles relaxed
When relaxed, the muscles are long and the chromatophore is small
44
Chromatophore muscles contracted
When contracted, it spreads out the chromatopohore and the muscles shorten
45
Squid eye
Its pupil stays horizontal, no matter the orientation
46
Chromatophores
Allows them to change colors for camouflage in their surroundings
47
Mouth of squid
Associated with the beak. Beak is behind the radula that rips and shreds food. The salivary glands has toxins
48
Squid siphon (modified foot)
Where H2O exits mantle cavity at a high velocity - allows jet propulsion
49
How many tentacles do squids have and what are the function of suckers?
They have 2 tentacles and suckers are present on each of them. They are sensitive chemoreceptors for touch
50
Squid's muscular mantle - function of radial and circular muscle
Radial muscle - when it contracts, it sucks in H2O Circular muscle - when it contracts, H2O leaves
51
Squid fin
Stabilized animal to prevel roll
52
Squid pen
Provides structural integrity along longitudinal axis of the visceral hump
53
Types of reproduction in Mollusca
Sexual - direct, indirect, and mixed Some are dioecious, hermaphroditic, and adelphophagio (which is the consumption of one embryo by another in utero)
54
Why do gastropods detort?
Ancestors had the developmental pattern of torsion, but the lack of shell relaxes it and goes back to posterior
55
3 types of Opisthobranchia in gastropods
Aeolid nudibranch Apylsiomorpha Dorid nudibranch
56
Kleptoplasty
It means to steal the chloroplast of its food. Allows opisthobranchs to be a plant-like gastropod
57
Kleptocnidae
It means to steal the cnidae of its food. Stores it in its cnidosac and fires when threatened
58
Characteristics of aplysiomorpha sea slug
Mouth Gut Mantle cavity Gill, which is enveloped by epidermis Anus
59
Characteristics of dorid nudibranch sea slug
Mouth Gut Branchial plume - gill Anus
60
Characteristics of aeolid nudibranch sea slug
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

BIOL 205 (13 decks)

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