Flashcards in 13. Mollusks Deck (29):
Mollusks are part of which subgroup?
How large is the animal group of mollusk?
Second largest after arthropods
Mollusks - diversity?
Highly diverse in response to environment
- Terrestrial or aquatic
- Different morphology, mode of nutrition, reproduction
Mollusca - body shapes?
Bilaterally symmetrical, triploblastic, coelomate protostomes
Mollusca are ..... larvae
Trochophore larvae (marine mollusks)
Major groups of mollusca?
Mollusk body plan?
- Foot at bottom
- Visceral mass
Contains gills (if aquatic) or acts as lung (if terrestrial)
Characteristics of polyplacophora?
Segmented shell (8 overlapping plates)
Polyplacophora - feeding?
Omnivorous - radula scrapes algae & bryozoans
Characteristics of bivalvia?
- Reduction of head
- Hinged shell
- Enlargement of foot
- Mantle cavity modified by siphons
- Enlargement of gill
- Relatively sessile
- Filter feeders
- Broadcast spawners
Extensions of posterior mantle
Water flows in mantle cavity and then across gills that act as filters for food
Bivalvia close shell...
With their large adductor muscles
Mantle of bivalvia is lined with...
Eyes - to detect motion and light
How large is the gastropoda group?
Most diverse group of mollusks
Gastropoda - habitat?
Terrestrial or aquatic
Gastropoda - feeding?
Herbivores, predators, scavengers
Gastropoda - reproduction?
- Internal or external fertilization
- Either dioecious or hermaphroditic, but can produce only sperm or eggs at one time
Some cool stuff gastropods do with their body?
- Torsion (twisting of body - 180 degrees rotation of visceral mass, mantle cavity, anus moved over head)
- Coiling of visceral mass
Characteristic of land snails?
Eyes on tips of tentacles
Characteristic of cone snail?
Radula modified into toxic harpoon (peptide toxins)
Some gastropods have nudibranchs which allows....
Some gastropods prey on tentacles of ......
Cnidarian polyps and re-used the cnidocytes
Body characteristics of cephalopoda?
- Subdivided foot (arms, tentacles)
- Enlarged head, reduced shell)
Cephalopods - feeding?
As predators, cephalopods have...
- Excellent vision
- Complex behaviour (visual communication with colour and texture, cryptic colouration)
- Ink sac for defense
- Closed circulatory system
- Mantle & siphon used for jet propulsion
- Arms with suckers &/or hooks - some have 2 elongated tentacles
Separate sexes!! (with elaborate courtship)
- Internal fertilization (males transfer sperm via specialized arm - hectocotylus)
- Females die after laying eggs (or after eggs hatch)
- NO TROCHOPHORE LARVA
Nautilus - example of a cephalopod. Characteristics?
- 80-90 arms
- Regulate buoyancy with gases in chambered shell
- Only extant shelled cephalopod