Mollusca Test Flashcards
Radula
Tongue with rough scraping teeth used for feeding
What are two methods mollusk use to feed?
Filter feeders (clams, oysters) and predation (squid, octopus)
All classes EXCEPT ___________ have a radula
Bivalves and aplacophora
Visceral mass
Digestive system, excretory system, reproductive organs
What does the mantle do?
Secretes shell
What are the 3 layers of shell?
Periosteum
Prismatic
Nacreous
What is the outside layer of a shell?
Periosteum
What is the middle layer of a shell that gives it strength?
Prismatic
What is the inner “mother of pearl” layer of a shell?
Nacreous
Most mollusks have an _____ circulatory system
Open
Because there’s no distinction between blood and interstitial fluid this is called
Hemolymph
What are gills also called
Ctenidia
What are the kidneys called?
Nephridia
What are the seven classes of mollusca?
- gastropada
- bivalvia
- Cephalopoda
- Scaphopoda
- aplacophora
- monoplacophora
- polyplacophora
How do most mollusks reproduce?
External fertilization
What are characteristics of gastropada?
Shell conical, coiled, or absent
What is the largest class of mollusks?
Gastropada
What is torsion?
Developmental process in which the body twists into permanent loop that rearranges organs and brings them together allowing body to draw into spiral shell
What is the operculum?
Protects the mouth of the gastropod and acts as a trap door
What is the gastropod that has no shell?
Nudibranch (sea slug)
What are characteristics of bivalvia?
- contain mollusks with two shells
- laterally compressed for filter feeding
- shell closed by adductor muscles
- not all bivalves burrow, mussels secrete byssal threads to attach to rocks, oysters cement left shell to hard surface
- scallops live unattached, can swim short distances
How do cuttlefish differ from squid and octopuses?
By having an internal shell for buoyancy (cuttlebone)
How do squid differ from cuttlefish and octopuses?
Streamlined body for open water
How are octopuses different from cuttlefish and squid?
Have no shell and live in rocky reefs
Nautilus
Have external shell and can live in depths of 2000 feet
-has most tentacles or arms
What are characteristics of the class Cephalopoda?
- use siphon to rapidly shoot water to escape/catch food
- siphon can rotate in any direction to change speed/ direction
- all but nautilus have ink sac opening
- have pigment called chromatophores
Monoplacophora
-“one plate”
Polyplacophora
Have oval shell consisting of 8 plates bounded by girdle
-ex: chiton
Scaphopoda
(Tusk shells) marine sand burrowers with tusk or toothed shells
Aplacophora
Lack of shell
-ex: worm like species
All mollusks have
Mantles
