Phylum Mollusca Flashcards
What is the primary method of excretion in Phylum Mollusca?
Nephridia
Metabolic waste leaves through a pore into the mantle cavity and gets washed away.
What type of fertilization occurs in terrestrial mollusks and cephalopods?
Internal fertilization
Most mollusks have separate sexes, except for some hermaphroditic species like snails and slugs.
What is the larval stage of mollusks called?
Trochophore larva
What type of circulatory system do most fast-moving mollusks, such as cephalopods, have?
Closed circulatory system
In a closed circulatory system, blood is contained in vessels at all times.
What is the main function of gills in mollusks?
Gas exchange
Most gas exchange occurs with gills located within the mantle.
What structure do all mollusks, except bivalves, possess for feeding?
Radula
The radula is a rasping tongue with tiny teeth used for scraping food into the mouth.
Which class of mollusks is characterized by having ‘2 valves (shells)’?
Class Bivalvia
Examples include clams, oysters, scallops, and mussels.
What is the main role of mollusks in the environment?
Important source of food for organisms including humans
They also serve as hosts for many parasites and environmental monitors of ocean water.
What type of nervous system do most mollusks have?
Mainly simple nervous system
This includes ganglia and nerve cords, with most having simple eyes.
What are the five main parts of the general body plan of mollusks?
- Head
- Foot
- Mantle
- Visceral mass
- Shell
What is the meaning of the name ‘mollusca’?
Soft-bodied animals
Fill in the blank: The shell of a mollusk can be _______ or reduced.
absent
What type of symmetry do mollusks exhibit?
Bilateral symmetry
What are the three main layers of cells in coelomate mollusks?
- Ectoderm
- Mesoderm
- Endoderm
What is a notable feature of the nervous system in cephalopods?
Well-developed brain
Cephalopods have a complex nervous system with advanced sensory capabilities.
What do bivalves primarily use for feeding?
Filter feeding using their gills
True or False: All mollusks have an external shell.
False
The shell can be absent or reduced in some species.
Which class of mollusks includes squids and octopuses?
Class Cephalopoda
This class is characterized as ‘head foot’.
What is the primary habitat of most mollusks?
Mainly aquatic, some terrestrial
What adaptation do terrestrial mollusks like snails and slugs require?
Moist environments
The thin membrane around their mantle cavity acts as a primitive lung.
What the habitat of phylum mollusca?
Mainly aquatic, some terrestial
What are examples of Phylum mollusca?
clams, oysters, snails, slugs, squid, octopus
How many cell layers?
Coelomate 3 cell layers
What does trochophore larvae mean (which all of them have)
free swimming larvae with lots of cilia
