mollusca Flashcards

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1
Q

animals in the phylum mollusca are calcareous, what does this mean?

A

they have a shell enclosing a soft body, but the shell may be lost or reduced in many taxa

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2
Q

what are some characteristics of mollusca?

A
  1. they have a complete digestive system with a mouth
  2. they have a true coelom
  3. open circulatory system (no blood vessels and the coelom is small)
  4. not clearly segmented
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3
Q

mollusca have a mantle, what is it?

A

a thin layer of tissue that secretes the shell

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4
Q

how do molluscs move?

A

muscular ventral foot

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5
Q

where are a molluscs organs?

A

inside the visceral mass above the foot

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6
Q

molluscs have a radula, what is it?

A

a mouthpart that has a strap-like rasping (conveyor belt with hooks/spikes)

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7
Q

how do molluscs breathe?

A

gills for gas exchange and sometimes feeding

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8
Q

what are the three classes of molluscs?

A

gastropoda, bivalvia, cephalopoda

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9
Q

what is the most abundant class of molluscs?

A

gastropoda

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10
Q

what animals does the class gastropoda encompass?

A

snails and slugs

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11
Q

how do gastropods move?

A

through slime excretion, then use their muscular foot to move across the substrate

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12
Q

during the larval stage, gastropods undergo _________. what is it?

A

torsion - visceral mass twists during development where their anal opening is over their head

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13
Q

do gastropods have direct development?

A

only terrestrial and freshwater species, marine species have a larval stage

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14
Q

how do land snails and slugs exchange gasses?

A

using a lung, which is the lining of their mantle cavity

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15
Q

gastropods have a division called nudibranchs, what are they and their characteristics?

A

marine shell-less gastropods (sea slugs)
1. many are bright and vibrantly colored
2. protected by nematocysts of cnidarians (other animals)

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16
Q

how are nudibranchs protected by the nematocysts of cnidarians?

A

eat cnidarians, but prevent their nematocysts from firing but instead storing it in their own tissues and firing the nematocysts when threatened

17
Q

where does the term ‘bivalvia’ come from?

A

having two hinged shells

18
Q

what animals does the class bivalvia encompass?

A

clams, oysters, muscles and scallops

19
Q

what are some characteristics of bivalves?

A
  1. filter feed by drawing water through the gills
  2. no radula (no definitive head)
  3. most are sedentary (can move if needed)
20
Q

what animals does the class cephalopoda consist of?

A

squids, cuttlefish and octopus

21
Q

do cephalopods have a shell?

A

no external shell (except nautilus) and some have internal shell remnants (cuttlefish)

22
Q

how do cephalopods eat?

A

long tentacles that have suckers or hooks around their mouths

23
Q

do cephalopods have a radula?

A

no, it was modified into a biting beak

24
Q

how do cephalopods move?

A

they have a siphon (a fused tube of the mantle) in which they propel water though

25
Q

cephalopods are the only molluscs with a?

A

closed circulatory system which supports their active lifestyle

26
Q

do cephalopods have direct development?

A

yes

27
Q

cephalopods provide maternal care, what is that?

A

they protect their eggs until young hatch

28
Q

what are some characteristics of octopus?

A

excellent vision and have complex behavior