MOLLUSCA Flashcards

1
Q

General Characteristics of Molluscs?

A

Foot, mantle, shell.
Marine, freshwater, terrestrial
Coelomate protostomes (Spiralia).

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2
Q

5 classes of Mollusca

A

Class Polyplacophora (chitons)
Class Gastropoda (abalone, sea slugs, sea hares, terrestrial slugs and snails)
Class Bivalvia (clams, mussels, oysters, scallops)
Class Scaphapoda (tusk shells)
Class Cephalopoda (nautilus, octopus, squid, cuttlefish)

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3
Q

What type of symmetry?

A

Bilateral

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4
Q

Reduced coelom but with an extensive _______ comprising an open circulatory system with compartmentalized heart.

A

hemocoel

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5
Q

What are the 3 body regions

A

head, foot, visceral mass

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6
Q

Define the Mantle

A

thick epidermal-cuticular covering that secretes the shell

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7
Q

What is housed within the mantle cavity?

A

ctenidia (gills), anus, opening to kidneys and reproductive tract, and osphradia (sense organs)

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8
Q

What is the radula?

A

a ribbon of recurved chitinous teeth that often functions as a scraper to remove food particles for ingestion

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9
Q

What controls the radula?

A

the odontophore

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10
Q

What type of kidneys?

A

Metanephridial

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11
Q

What type of larvae?

A

Trochophore and veliger

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12
Q

What stage does torsion occur in gastropods?

A

Veliger larvae stage

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13
Q

3 layers of the body wall?

A

cuticle, epidermis, muscle layers

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14
Q

How does water flow thru the mantle cavity?

A

driven by cilia
In cavity —> over gills —> over nephridiopores and anus —> out.

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15
Q

What are the 3 layers of the shell?

A

Three layers: periostracum made of scleretized proteins (conchin), prismatic made of CaCO3 in columnar conchin matrix, and nacreous made of CaCO3 with some conchin in sheet-like pattern (mother-of-pearl).

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16
Q

Which animals have reduced shells?

A

sea hares, squid pen, cuttle bone

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17
Q

Which animals have lost shells?

A

Octopus, nudibranchs

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18
Q

What happens during torsion on gastropods? What does it result in?

A

Rotation of visceral mass and overlying mantle and shell 180 degrees with respect to foot and head.
Gut ends up U-shaped and incipient organs are switched left to right.

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19
Q

How do gastropods and polyplacophorans move?

A

Crawling (direct and indirect waves)
Mucus alternately acts as a glue and allows sliding.
Some gastropods use cilia (moon snails).

20
Q

How do Bivalves move?

A

Burrowing, byssal threads, swimming

21
Q

How do Cephalopods move?

A

Radial and circular muscles. Contraction of circular muscles forces water out siphon or funnel for swimming.
Crawling along substratum.

22
Q

Describe the Cephalopod nervous system

A

Well developed -
Brain with lobes.
Large nerve to all parts of body.
Large optic nerves.
Memory in octopus.

23
Q

What do osphradia do?

A

chemosensory and sensing sediment

24
Q

What do statocysts do?

A

balance and oreintation

25
Q

What type of sense organs are tentacles and rhinophores?

A

chemosensory

26
Q

What are chromatophores?

A

Cells for color change in cephalopods.
Contain pigments and are under neuronal and hormonal contol.

27
Q

what is Macrophagy

A

eating “large” things

28
Q

What is Microphagy

A

eating “small” things

29
Q

How do gastropods eat?

A

using their radula

30
Q

How do Cephalopods eat?

A

Cephalopods highly mobile predators.
Catch prey with suckered arms.
Neurotoxins associated with beak in octopus.

31
Q

How do Bivalves eat?

A

Ctenidia modified for particle capture

32
Q

What is the function of labial palps in Bivalves?

A

sorting food particles

33
Q

What are pseudofeces? (Bivalves)

A

non-organic particles that are excreted (they never entered the digestive system - kicked out by labial palps)

34
Q

Complete or Incomplete digestive system?

A

Complete

35
Q

What is the purpose of a crop?

A

Food storage

36
Q

What type of circ system?

A

Open - except for Cephalopods (closed)

37
Q

How do terrestrial gastropods do gas exchange?

A

they have a “lung” - a vascularized mantle cavity

38
Q

What kind of waste do aquatic molluscs excrete? terrestrial?

A

aquatic - ammonia
terrestrial - uric acid

39
Q

Hermaphroditic or gonochoristic?

A

most gonochoristic (bivalvia, cephalopoda, gastropoda)

some hermaphroditic (simultaneous and sequential) (gastropoda)

40
Q

What type of cleavage?

A

spiral

41
Q

mouth from ______?

A

blastopore

42
Q

cell fate determined early or late?

A

early

43
Q

What type of development?
(direct, indirect, mixed)

A

can be all
terrestrials and cephalopods direct
nudibranchs mixed

44
Q

what is the excretion organ?

A

paired tubular metanephridia

45
Q

Those with indirect development - what type of larva?

A

Free swimming trochophore larva