The Molluscs

Question 1

one of the largest and most diverse phyla in the animal kingdom, with over 100 000 extant species and about 70 000 fossil species

Answer 1

phylum

Mollusca

Question 2

the Latin word

mollia, means?

Answer 2

Soft

which alludes to the typically soft bodies of Molluscs

Question 3

True or False

phylum Mollusca contains
several taxa that are extremely dissimilar looking.

Answer 3

True

Question 4

What forms a mantle, which secretes calcareous spicules or one or more shells

Answer 4

Dorsal epithelium

Question 5

cuticular band of teeth in the esophagus, used for feeding

Answer 5

radula

tho not present in bivalves

Question 6

ventral body wall muscles develop into a….

Answer 6

locomotory or clinging foot

Question 7

How many described living species?

Answer 7

100,000

Question 8

How many fossils species

Answer 8

70,000

Question 9

True or False

the molluscan body plan probably the most malleable in the animal kingdom

Answer 9

True

Dissimilar-looking organisms

Question 10

thin, outer organic layer

Answer 10

Periostracum

Question 11

thick, calcareous middle layer

Answer 11

Prismatic layer

Question 12

thin, innermost calcareous layer

Answer 12

Nacreous layer

Question 13

Both the organic and inorganic components of the shell are secreted by specialized tissue
known as

Answer 13

Mantle

Question 14

How are pearls formed

Answer 14

a grain of sand, parasite, or other foreign particle becomes trapped between the mantle
and the shell’s inner surface

Question 15

usually houses the comblike molluscan gills

serves as the exit site for the excretory, digestive, and reproductive systems

Answer 15

Mantle Cavity

Question 16

comblike molluscan gills are known as

Answer 16

Ctenidia (G: comb)

Question 17

True or False

A Ctenidium (gill) may have a purely respiratory function or collection and sorting of
food particles

Answer 17

True

Question 18

A chemoreceptor/tactile receptor generally

located adjacent to the ctenidium is known as

Answer 18

Osphradium (G: smell)

Question 19

What are the feeding apparatuses?

Answer 19

R - radula
O - odontophore
M - mouth
E - esophagus

Question 20

odontophore-radular assembly + complex musculature

Answer 20

Buccal mass

(bucca = L: cheek), or the Odontophore Complex

Question 21

consists of a firm ribbon composed of chitin and protein, along which are found numerous rows of sharp, chitinous teeth

Answer 21

Radula

Question 22

The ribbon is produced from a Radular sac and is underlain by a supportive cartilage-like structure called

Answer 22

Odontophore ( G: tooth bearer)

Question 23

Feeding of molluscs is through

Answer 23

rasping

Question 24

True or False

As old teeth are worn down or broken off at the anterior end of the radular ribbon, new teeth are continually being formed and added onto the ribbon’s posterior end in the radular sac.

Answer 24

True

Question 25

extends its proboscis and harpoons the fish through a “lightning strike cabal” of toxins causing almost instantaneous immoblilization of prey.

Answer 25

. Conus striatus

Question 26

use net strategy to capture school of fish hiding in reefs at night. Once it has engulfed them, it uses a “nirvana cabal of toxins” to make the fish quiescent for stinging them and causing an irreversible neuromuscular paralysis.

Answer 26

Conus geographus

Question 27

What class has a defining characteristics of shell that forms 7-8 separate plates

Answer 27

Class Polyplacophora G: many plate-bearing

Question 28

How many species does Class Polyplacophora

Answer 28

800 species

Question 29

organs derived from mantle extending from holes of plates (light receptors or secrete periostracum)

Answer 29

Aesthetes

Question 30

True or False Articulating plates are either partially or largely embedded from the mantle

Answer 30

True

Question 31

What releases amylase-containing secretions into the stomach

Answer 31

Pharyngeal/sugar glands

Question 32

What class has a shell that has a series of eight overlapping and articulating plates covering the dorsal surface

Answer 32

Class Polyplacophora

Question 33

A chiton’s thick lateral mantle is called

Answer 33

Girdle

Question 34

Class that is not shell bearing

Answer 34

Class Aplacophora

Question 35

Class defining characteristics: - cylindrical, - vermiform body with the foot forming a narrow keel

Answer 35

Class Aplacophora

Question 36

How many species in Class Aplacophora are in deep ocean

Answer 36

300 species

Question 37

True or False Class Aplacophora have segmented body with numerous calcareous spines embedded in the outer cuticle

Answer 37

False Unsegmented body

Question 38

Defining characteristics: - 3-6 pairs of ctenidia - Multiple pairs of pedal retractor muscles - 6-7 pairs of nephridia

Answer 38

Class Monoplacophora G: one shell bearing Single, unhinged limpet-shaped shell

Question 39

How many extant species of Class Monoplacophora

Answer 39

20 extant species All marine collected at great depths of 2,000m

Question 40

Defining characteristics: - Visceral mass and nervous system become twisted 90-180 degrees (torsion) during embryonic development -Proteinaceous shield on the foot (operculum) to which columellar muscle attaches

Answer 40

Class Gastropoda

Question 41

A 180 degree counterclockwise twisting of the visceral mass, mantle, and mantle cavity during embryonic development Positions the gills, anus, and openings from the excretory and reproductive systems just behind the head and nerve cords, and twists the digestive tract into a "u-shape“ Allows the mouth and the anus to exit the shell at the same point

Answer 41

TORSION IN GASTROPODS

Question 42

- Reversal of torsion - Takes place during the larval stage and the animal regains bilateral symmetry - Nervous system becomes symmetrical and not twisted in the shape of 8 - Visceral loop and intestine becomes straightened - Pulmonata, Opisthobranchia

Answer 42

Detorsion

Question 43

- Marine and freshwater snails, predominantly marine - Generally free-living and mobile - Complete torsion

Answer 43

SC Prosobranchia | G: anterior gill; snails

Question 44

Foot of SC Prosobranchia bears a rigid disc of protein called

Answer 44

operculum

Question 45

* Soft, fleshy tube through which water is drawn into the mantle cavity and over the gill for respiration, locomotion, feeding, and reproduction * Equipped with chemoreceptors which "smell" or "taste" the water, in order to hunt for food

Answer 45

Siphon

Question 46

○ Includes sea hares, sea slugs, bubble shells ○ Almost all marine ○ < 1,100 species described

Answer 46

SC Opisthobranchia | G: posterior gill

Question 47

- Sea slugs - use nematocysts usurped from cnidarian prey for defense - produce chemical defenses housed by cerata - Possess rhinophores in the second pair of tentacles located dorsally of the head (chemosensors)

Answer 47

ORDER NUDIBRANCHIA

Question 48

- Sea hares - Found in shallow waters and rock pools - Prominent tentacles on the head resemble rabbit ears - Releases defensive secretion ink (purple) andopaline E.g. Aplysia, Dolabella

Answer 48

ORDER ANASPIDEA

Question 49

- Sea butterflies | - Foot modified to produce wing-like flaps called parapodia for swimming

Answer 49

ORDER PTEROPODA

Question 50

Mantle cavity of SC Pulmonata is highly vascularized and functions as lungs through an opening called

Answer 50

pneumostome

Question 51

Few are marine; if present, in intertidal zones and estuaries only

Answer 51

SC Pulmonata - Mostly terrestrial or freshwater - Few with operculum - Possess long radula in keeping with herbivorous diet - Head bears 2 tentacles

Question 52

True or False Torsion of SC Pulmonata can reach up to 180

Answer 52

False Torsion limited to 90º so nervous system not greatly twisted and mantle cavity opens on the right side

Question 53

chitinous or calcareous accessory organ that are thrust into the partner during mating among pulmonate gastropods

Answer 53

Love dart

Question 54

DC: - Two-valved shells - Body is flattened laterally

Answer 54

``` Class Bivalvia (~ Pelecypoda) - G: two valved ```

Question 55

Class bivalvia has _____ species which includes clams, scallops, mussels, and oysters

Answer 55

> 15,000 species - Primarily marine, but about 10-15% are in freshwater

Question 56

- Lack of cephalization - Spacious mantle cavity - Sedentary lifestyle - Absence of radula/odontophore complex - Diverse feeding habit

Answer 56

Class Bivalvia

Question 57

- Includes Nucula sp. - Morphologically primitive state of bivalve - Bipectinate gills - Deposit feeding

Answer 57

SC Protobranchia | G: first gill

Question 58

- Include familiar bivalves such as clam, mussels, scallops - Gills modified to collect suspended food particles - Secretion of attachment by byssal or byssus gland in the foot

Answer 58

SC Lamellibranchia | G: plate gill; mussels

Question 59

- Small group of carnivorous bivalves and on pieces of decomposing animal tissue - All very deep marine water - Ctenidium highly modified, lacking filaments and forming muscular septum perforated by ciliated openings - Feed as vacuum cleaners sucking on small crustaceans and annelids Stomach lined with chitin

Answer 59

SC Septibranchia | G: fence gill; shipworms

Question 60

- DC: ○ tusk-shaped, conical shell open at both ends ○ development of anterior, thread-like adhesive feeding tentacle (captacula)

Answer 60

Class Scaphopoda | G: spade foot; tusk shell

Question 61

DC: ○ Shell divided by septa with chambers connected by siphuncle (yellow arrows) ○ Closed circulatory system ○ Foot modified to form flexible arms and siphon Ganglia fused to form a large brain encased in cartilaginous cranium

Answer 61

Class Cephalopoda G: head foot; Includes squids, octopi, Nautilus

Question 62

- Fast-moving, active carnivores capable of complex behavior - Exclusively marine - Derivatives of the molluscan foot are the siphon, arms and tentacles (8-10) - Possess two eyes with cornea, lens, iris, diaphragm and retina thus focusable and image-forming - Closed circulatory system with systemic and branchial hearts

Answer 62

Class Cephalopoda

Question 63

○ Soft-bodied, shell-less cephalopods ○ chromatophores overlay iridocytes ○ photophores ○ most have ink sac discharged through anus

Answer 63

Subclass Coleoidea

Question 64

colored cells

Answer 64

chromatophores

Question 65

reflective cells

Answer 65

iridocytes

Question 66

light organs

Answer 66

photophores

Question 67

True or False female octopi have hectocotylized arms

Answer 67

False Male octopi

Question 68

Highly modified arm that transfers spermatophores

Answer 68

hectocotylus

Question 69

Packets of sperms

Answer 69

Spermatophores

Question 70

○ 5 or 6 species possessing true shell ○ shell divided by septa into series of compartments ○ septa penetrated by siphuncle - cameral fluid in chambers

Answer 70

- Subclass Nautiloidea

Question 71

calcified tube with enclosed strand of vascularized tissue

Answer 71

Siphuncle

Question 72

Movement of Subclass Nautiloidea is through

Answer 72

Jet Propulsion