13 phylum mollusca

Question 1

Phylum MOLLUSCA
(molluscus = “soft”)
* 90,000 living species (70,000 fossil species)
* Soft bodied invertebrates
* Modes of feeding may be herbivorous, predaceous carnivores, filter feeders, or parasitic
* Marine, freshwater, and terrestrial habitats
* Bilaterally symmetrical
o In some, they display Bilateral Asymmetry (body divided into left and right, but are not equal)
* Unsegmented; often with definite head
* Level of complexity: organ-system grade
* Triploblastic, eucoelomate

Answer 1

Phylum MOLLUSCA

Question 2

a structure unique to Mollusca; a protrusible, tongue-like
organ which consists of rows of tiny teeth found within the mouth

Answer 2

Radula

Question 3

– a ventral, sole-like structure for locomotion and capturing food

Answer 3

foot

Question 4

“visceral” means

Answer 4

organs

Question 5

a sheath of skin that hangs down on each side of the body to protecting the soft parts
of the visceral mass.

Answer 5

Mantle

Question 6

the space between the mantle and visceral mass

Answer 6

mantle cavity

Question 7

secreted and lined by the mantle. Absent in some groups.

Answer 7

Shell

Question 8

outer layer, composed of conchiolin

Answer 8

Periostracum

Question 9

middle layer, composed of calcium carbonate

Answer 9

Prismatic layer

Question 10

very thin inner layer called “nacre” that lies next to the mantle; increases in thickness during life of animal; composed of very crystalline calcium

Answer 10

Nacreous layer

Question 11

formed in clams.

Answer 11

pearls

Question 12

– a paired comb-like or feather-like respiratory organ or gill with many filaments that line up in a row

Answer 12

Ctenidium (plural: Ctenidia)

Question 13

Most have a pair of kidneys called:

Answer 13

metanephridia

Question 14

of several pairs of cerebral ganglia

Answer 14

brain

Question 15

main ganglia in head area

Answer 15

Cerebral

Question 16

main ganglia near gills/ctenidia

Answer 16

Pleural

Question 17

main ganglia that controls the foot/tentacles

Answer 17

pedal

Question 18

ganglia that controls the visceral organs

Answer 18

visceral

Question 19

ganglia around the mouth

Answer 19

buccal

Question 20

free-swimming larva that emerges from
the egg (or occurs inside the egg in some molluscs)

Answer 20

trocophore

Question 21

the larval form that follows after trocophore stage in many molluscan groups.

Answer 21

veliger

Question 22

– a one-piece shell that is coiled (but some species it is uncoiled)Depending on direction of coiling, it may be right-handed or left-handed (this is genetic)

Answer 22

Univalve shell

Question 23

color changing cell in scattered in the epidermis; they are under nervous and
hormonal control

Answer 23

Chromatophores

Question 24

secretes a dark fluid called sepia into an ink sac, that empties to the rectum to release a cloud of ink when animal is alarmed.

Answer 24

ink gland

Question 25

one arm of adult males is modified as an intromittent organ that is used to pluck a spermatophore from his own mantle cavity and insert it into the mantle cavity of a femal. Eggs are attached to stones or other objects.

Answer 25

Hectocotylus