Mollusca Flashcards
The structure of molluscs that forms the shell and houses the gills is the A) mantle. B) epidermis. C) gastrovascular cavity. D) odontophore.
A) Mantle
The structure that is used for feeding in most molluscs is the A) buccal cavity. B) radula. C) mouth. D) odontophore.
B) Radula
The first larval stage that is typical of molluscans is the A) planula. B) veliger. C) actinotroph. D) trochophore.
D) Trochophore
The trochophore larva indicates a common ancestry between Mollusca and ……….
Annelida
Which of the following structures do bivalves use in the process of digestion? A) a crystalline style B) a jaw C) peristaltic muscles D) byssal threads
A) A crystalline Style
Torsion is a process that rotates the _________ of the body of gastropods.
Viscera
In molluscs, the shell is secreted by the A) mantle. B) gills. C) ctenidia. D) odontophore
A) Mantle
The type of excretory organs possessed by molluscs is A) pronephridia. B) metanephridia. C) mesonephridia. D) telonephridia.
B) Metanephridia
Some gastropods have a horny plate that covers the shell aperture; this structure is called an osphradium. True or False
False
What is the function of the osphradium
A sense organ to test the purity of water passing through the gills
A mollusc that has a shell of two valves and is usually a filter feeder is a scaphopod. True or False
False
a class of molluscs that comprises the tusk shells is a ……..
Scaphopoda
A mollusc that is an active predator, has tentacles, and is marine could only be classified in the class……..
Cephalopoda.
Unlike the other classes of the molluscs, which have a heart and a hemocoel, the members of class Cephalopoda have a closed circulatory system. True or False
True
the primary body cavity of most invertebrates, containing circulatory fluid is called……
Hemocoel
Most of the molluscs are dioecious but some of the gastropods are hermaphroditic. True or False
True.
What are some of molluscs external characteristics?
Unsegmented/Bilaterally symmetrical. Calcium carbonate shell (Some no shell), 3 body regions.
What are the 3 body regions?
Head - Foot - Visceral hump (Contains the digestive/respiratory/reproductive/excretory systems)
What are the general CNS characteristics
Brian/Paired ventral nerve cord. Developed sense organs i.e Statocysts (Balance), Photoreceptors, or eyes.
Cephalopods have highly developed brain/sight/touch/memory/shape recognition.
What are molluscs general modes of transportation
Foot.
Tentacles/jet propulsion (Water siphons) in Cephalopods
What are molluscs general modes of respiration?
Cavity between mantle holds the gills (‘Lung’) Cilia move water across ventral -> dorsal, with a counter current of blood
What are molluscs circulation system
Open (Closed in Cephalopods), Heart and haemocoel
How do molluscs feed
Mouth, and Radula (Rasping food), Bivalves filter feed. Cephalopods use beak/radula. Complete guy, with intracellular digestion.
How do molluscs excrete waste
Large folded paired Metanephirdia (Excretion glands) that have selective re-absorption. Aquatic = Ammonia
Land = urea/uric acid.
How do molluscs reproduce
Most are dioecious (many Gastropods are Hermaphrodites). Aquatic=External, Land=internal fertilisation. Trochopore larvae -> Veligar larvae Land forms do this in the egg.
What prof is there for Annelids and Molluscs having a common ancestry
Both having a Trochophore Larvae.
What are the major morphology features of Bivalves
Mostly marine/sedentary life style - Shell Bi-valved - Laterally compressed, Small head, Absent radula - Light sensitive eyes/statocysts - Gills - Palp
What are the major digestion features of bivalves
Crystalline style ->Rotates against gastric shield/acidic enzymes -> Intracellular digestion via Phagocytosing Amoeboid cells
What are the 2 major bivalves sub-classes
Protobranchia (Deposit feeder)
Lamellibranchia
What are some of protobranchias features
Deep oceans
Mucous coated palps that collect-sort-and ingest food
Gills (can aid in filtration)
Burrows foot into ground
What are some of Lamellibranchia features
Life styles (Soft bottom/Attached surface/Unattached surface dwellers/ Borers some Burrow/ Commensals Parasites) Inhalent/Exhalent siphons (Zooxanthellae Symbiotic aglae)
Define and explain Torsion
A 180 rotation of the mantle. Results with Anus near the Head/mouth. Greater forward ventilation.
Loss of right side mantle cavity
Single gill on left
Filamentous = easy to clog
What are Pulmonates
Snail
Hermaphroditic and direct development
What is Protandry, and give an example
Males that go through an irreversible sex change when no females are available. Crepidula forhicata (Slipper limpet)
