Molluscs

Question 1

Define mollusk

Answer 1

• Scienfitic name “phylum mollusca”
• soft bodied animals with external or internal shell (some have no shell)
• highest number of species of marine life (10,000)
• bilaterally symmetrical or asymmetrical

Question 2

Examples of a mollusk

Answer 2

clams, snails, octopus, nautilus…ect.

Question 3

Body parts of a mollusk

Answer 3

• Foot
  > muscular structure used in feeding and locomotion
• Visceral mass
  > internal organs
• Mantle
  > soft later of tissue surrounding the visceral mass
  > secretes shell (made of calcium carbonate/CaCO3)
• Shell
  > found in most mollusks
  > made of CaCO3 by glands in the mantle
  > outer layer called the periostracum (made of conchiolin - tough)
  > second layer is prismatic layer (made of calcium carbonate crystals)
  > third layer is nacreous layer (colorful, irridescent)
• etenidia
  > gills arranged in pairs
• Shell
• Etenidia

Question 4

Types of feeding in mollusks

Answer 4

• filter feeders (e.g clams)
• carnivores (e.g squid)
• herbivores (e.g snails)

Question 5

What is a radula in a mollusk?

Answer 5

• tongue shaped structure made of the carbohydrate chitin

> scrapes food off rocks/surfaces
OR
drills into shell of mollusks, inserts radula and stomach into shell, digests and breaks down the visceral mass

Question 6

What is a nudibranch?

Answer 6

• aka sea slugs
• breath through gills on back and through the skin
• hermaphrodites (produce male and female gametes)
• rhinopores (small tentacles on head used to sense surroundings)
• when they feed on anemones, they incorporate their tentacles onto their skin surface
• when they teed on algae, they incorporate chloroplasts into skin
• bright colors warn of danger (aposematic behavior)

Question 7

What is a conch?

Answer 7

• large, flaring lip colored rich pink, orange and yellow
• crawl along using muscular foot
• feed on algae/marine plants
• commin food source in Caribbean

Question 8

Class Gastropoda

Answer 8

• single shells that cover the body or no shell
• operculum
  > trapdoor that protects opening to shell
• osphradium
  > sensory cells next to gills used to detect dead meat or prey
• escape methods include bright colors, poison, ink squirt, discharge non-fired nematocysts from a cnidarian it ate earlier