Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Life of Earth 2 > Molluscs > Flashcards

Molluscs Flashcards

1
Q

Mollusca is a v large phylum. Which is the only phylum larger?

A

Arthropods

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the features of a generalised mollusc?

A 
> bilaterally symmetrical 
> poorly cephalised 
> aquatic
> moves & grazes over hard surface 
> radula = scraping tongue w/ teeth used in feeding
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the 3 layers of a mollusc shell?

A
  1. Periostracum - bright colours
  2. Ostracum - 2 layers make up bulk of shell
  3. Hypostracum/Nacre - pearlescent layer where body lies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 6 major mollusc clades?

A 
Aplacophora
Polyplacophora
Bivalvia
Gastropoda
Scaphopoda
Cephalopoda
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Which 2 clades have the greatest diversity?

A

Bivalves

Gastropods

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are aplacophores?

A

Worm-like molluscs w/ no shells

Have mix of primitive & specialised features

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Which primitive features do aplacophores have?

Which specialised features do aplacophores have?

A

Poorly developed head
Covered by cuticle w/ calcareous scales/spicules embedded

Reduced foot
Loss of radula & gills

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why might the aplacophores not have ‘lost’ their radula or gills?

A

If they’re at the base of the mollusc tree

–> might never have had them in the 1st place

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What do polyplacophora have?

A 
Many shell plates - always 8 overlapping
No cephalic eyes or tentacles
Multiple gills 
Segmented shells 
Indistinct head
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are polyplacophores adapted for?

When did they evolve?

A

Adhering to rocks & moving around grazing bacteria & algae

Diverged early from main line of molluscan evolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which clade is most like a generalised/ancestral mollusc?

A

Monoplacophora

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How many monoplacophora genera & species are there?

A

3 genera

11 species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How many pairs of gills do monoplacophores have?

A

5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Give examples of bivalves.

A

Clams
Oysters
Mussels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the features of bivalves?

A 
>Laterally compressed
>Shell of 2 hinged halves 
>Infaunal or epifaunal 
>Filter feeders - incurrent and excurrent siphon via 2 tubes 
>Poorly cephalised
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What do bivalves have within their hinge?

A

Abductin = elastic protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How can you tell how deep a bivalve burrows?

A

By the length of their siphons

18
Q

How do bivalves open & close their shells?

A 
Open = relax muscle
Close = contract muscle
19
Q

Which clade do Blue Mussels belong to?

What specialised structure do they have?

What else do they produce?

A

Bivalvia

Byssal threads
- pull off predators e.g. whelks

Mussel glue protein - stick themselves into a raft

20
Q

What are the features of scaphopods?

A

> Tusk or tooth shells

>Elongated cylindrical tube - open at both ends

21
Q

What is the scaphopod specialism?

A

Burrowing marine molluscs

22
Q

What are the features of gastropods?

A 
> developed head
> only terrestrial molluscs
> motile - foot for crawling, burrowing, swimming
> shell forms deep protective retreat 
>torsion
23
Q

What is torsion?

What might it allow?

A

Twisting of the body through 180 anti-clockwise
- gills, anus & mantle cavity now lies behind head

Withdrawal of head into shell before foot

24
Q

What is the mantle cavity of a gastropod lined with?

What does this now function as?

A

Blood vessels

Lung

25
Q

What are the 3 groups of Gastropoda?

Which group is now known to be polyphyletic?

A

Prosobranch
Opisthobranch
Pulmonata

Prosobranch

26
Q

What does ‘prosobranch’ mean?

A

‘gills in front of the heart’

27
Q

What does ‘opisthobranch’ mean?

A

‘gill one behind and to the right of the heart’

28
Q

What type of torsion do opisthobranchs have?

A

Not full torsion

= 45 degrees

29
Q

What are the features of opisthobranchs?

Give examples.

A

> reduced/absent shell & mantle cavity
many are secondarily bilaterally symmetrical

Sea hares, sea butterflies, sea slugs (e.g. Nudibranchs)

30
Q

Why are Nudibranchs special?

A

> Can eat stinging cells from venomous jelly fish
don’t set off stinging cells
–> move them to extremities of their tissues & use to sting predators

31
Q

What does ‘pulmonata’ mean?

A

Pallial lung instead of gills

- breathe air

32
Q

What are the 4 examples of cephalopods?

A

Cuttlefish
Octopus
Squid
Nautilus

33
Q

What are the 4 general features of cephalopods?

A

> head has prehensile tentacles & arms
jet propulsion
carnivorous
majority = 6-70cm

34
Q

What are the highly derived features of cephalopods?

A 
> ink gland
> camouflage
> complex NS & behaviour 
> v developed eyes
> vascular system 
> internal fertilisation via a spermatophore (using male's copulatory appendage)
35
Q

What is the shell like in squid?

A

Reduced to ‘pen’ or ‘gladius’

- made of chitin

36
Q

What is the shell like in cuttlefish?

A

Internalised as ‘cuttlebone’

- used for buoyancy

37
Q

What are chromatophores?

What are the reflective cells underneath called?

A

Pigment-containing light-reflecting cells

Iridocytes

38
Q

What features do cephalopod eyes have?

A 
Cornea
Lens
Iris
Diaphragm 
Retina
39
Q

How do cephalopod eyes differ to mammalian?

A

Mammals - light focussed by altering shape of lens

Cephalopods - light focussed by moving lens toward or away from retina

40
Q

What can cephalopods hear?

What is this an adaptation to?

A

Only v low freqs

Being predated on by whales & dolphins that stun prey w/ sound
- become immune by tuning out sounds

41
Q

What is the respiratory pigment in cephalopods?

A

Hemocyanin

- only 25% as efficient in binding O2 as haemoglobin

42
Q

What are photophores?

Where are they found?

A

Cells that generate light

On the underside - useful for countershading if can match freq of light coming from above

Life of Earth 2 (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions