Lecture 6 Flashcards
What is a Coelom?
A body cavity in animals that provides space for internal organs and is used for functions like movement and organ development
What is the body cavity in animals that provides space for internal organs and is used for functions like movement and organ development
the Coelom
What is the term for the ancestral larval stage of many molluscs that has a spherical body shape and has bands of cilia?
Trochophore Larva
What are the bands of cilia used for in Trochophore Larva?
for swimming
What is the anterior portion (head-foot) of molluscs used for? (3)
- Feeding
- Sensory Input
- Locomotion
What is the name of the portion of the mollusc body that contains the internal organs; digestive, circulatory, and reproductive systems?
Visceral Mass
The Visceral Mass of the Mollusc body contains what?
Internal Organs; digestive, circulatory, and reproductive systems
What is the Radula?
a tongue-like organ with teeth - used for scraping food off surfaces and transporting it to the digestive system
Radula are found in all molluscs except…
Bivalves (and most solengastres)
What is the Odontophore?
a cartilaginous structure that supports the Radula and aids in its movement
What is the structure that supports the Radula and assists with movement?
Odontophore
What is the muscle structure thats used for locomotion, attachment to surfaces, and swimming?
Molluscan Foot
What is the sheet of skin (tissue) covering the visceral mass and soft body parts - and is responsible for secreting the shell?
the Mantle
What is the space between the Mantle ad the Visceral Mass?
Mantle Cavity
What are the respiratory organs found in the mantle cavity known as?
Ctenidia
The Ctenidia is involved in what function?
Gas Exchange using countercurrent flow (maximizing efficiency)
Most molluscs have what type of circulatory system?
an Open Circulatory System
What is the difference between an open and a closed circulatory system?
in an open system, blood is not entirely contained within vessels
in a closed system, blood flows entirely within vessels
Closed circulatory systems are found in what kind of molluscs?
Cephalopods
What is the outer organic layer of a molluscs shell called?
Periostracum
What is the purpose of the Periostracum?
it protects the shell from damage and erosion
What is the Periostracum composed of?
Conchiolin
What is the middle layer of the shell called?
the Prismatic Layer
What is the purpose of the Prismatic Layer of the shell?
its calcium carbonate crystals in its protein matrix provides strength and support
What is the innermost layer of the shell called?
Nacreous Layer
What does the Nacreous layer of the shell produce?
Nacre - (Mother of Pearl)
What are the paired excretory kidney-like organs known as?
Metanphridia
What are Dioecious organisms?
Organisms with distinct male and female sexes
What is the secondary larval stage in molluscs?
Veliger Larva
What is Conchiolin?
a protein that composes the outer layer of the Periostracum Layer in molluscs
What is Countercurrent Exchange?
mechanism where fluids flow in opposite directions for optimal substance transfer
What is a Siphon? What is its purpose?
A tube like structure used for drawing in water for respiration and expelling water for movement
What is a Nephrostome?
the opening of the Metanphridia into the coelom where waste is collected
What is the Nephridiopore?
the external opening of the Metanphridia where waste is excreted
Where is the waste excreted from in molluscs?
the Nephridiopore of the Metanphridia(s) in Molluscs
On one end of the Metanphridia is the _________ which opens into the ______; on the other end is the __________ which opens to the outside of the body to expel waste
Nephrostome; Coelom; Nephridiopore
What are the 3 layers of the shell in molluscs? (superficial - deep)
- Periostracum
- Prismatic
- Nacreous
Which of the mollusc types have a closed circulatory system?
Cephalopods
What structures are the “gills” of the molluscs
Ctenidia
What are the 3 Larval developmental stages?
- Trochophore Larva
- Veliger Larva
- Direct development
