Bivalves Flashcards
What phylum and class do they belong to
Mollusca
Bivalvia
When did they evolve and are there around today
Cambrian
Yes
What dies articulated mean
The valves are joined together but can move along the hinge lines
What does disarticulated mean
The valves are no longer joined together
What does equivalve mean
Valves of the same size
What does inequivalve mean
Valves of different size
What are siphons
Soft tissue that take in fresh water and filter it and removed used water
Where are most bivalves symmetry
Along the hinge line
How do you know if a bivalve is left or right (sinistral or dextral)
The direction of the umbone
Where is the umbone
It sits directly above the hinge line
What does the hinge itself consist of and rowdies it work
Protruding teeth and sunken pit-like sockets
These articulate against one another when the valves open and close, keeping the structure stable
On the outside f the shell, where the valves are joined what is there and what covers the area
Hinge plate
A ligament covers the area but decays in death
Where is the shell secreted
Mantle (part of the soft tissue inside the bivalve
What marks the position of the soft tissue
Palatial line on the inside of the shell
Finding it hard to remember the differences between Bivalves and Brachiopods?
Got to page 245 in the Geology OCR AS/A2 text book
What is the byssus
A group of thread-like structures made of a protein called collagen
What is a byssal notch
A shallow indentation or hole, which means the byssus does not interfere with opening and closing of the valves
What is cement
The calcareous substance secreted by the mantle and attaches the left valve to the substrate
What did they use to feed
Inhalant and exhalant siphons
What do the inhalant and exhaling siphons do
Inhalant-bring’s in fresh water
Exhalant-remove waste water
What removes particles from the water
The gills
How do some bivalves move
Using a muscular foot
What are the three types of epifaunal bivalves
Mytilus
Ostrea
Gryphaea
What is unique about Mytilus that no other type has
It is attached to the substrate by the byssus (allows lying in high-energy environment)
What does the layer of periostracum do (Mytilus)
Protects it from acidic rain/river water
Function of strong shell (Mytilus)
Lives in a high-energy environment
Streamline (Mytilus)
Protect against currents
Large adductor muscles (Mytilus)
To hold valves tightly together to stop the shell drying out in low tide
What is special about Ostrea
It is cemented
How do they attach to the sea floor (Ostrea)
By secreting cement for the mantle
What valve always attaches (Ostrea)
Left valve
Strong, thick shell (Ostrea)
To withstand high-energy environments
Strong adductor muscle (Ostrea)
To keep closed in high-energy currents
Vales of different sizes (Ostrea)
Larger left valve is cemented to the rock while right valve acts like a lid
What type of oyster is Gryphaea
Extinct
How did Gryphaea live
Rested on sea floor on a convex left valve so left valve was much bigger than right valve
What effect did this convex left valve give them (Gryphaea)
Snow shoe effect
What are the two examples of infaunal bivalves
Crytherea
Solen
How deep of a burrower is Crytherea
Shallow
What part is shallow (Crytherea)
Palatial sinus, indicating short siphons
What do ribs/growth lines show (Crytherea)
Help grip the sediment when burrowing
Streamline shell (Crytherea)
To help move through the sand easier
Large adductor muscle scars (Crytherea)
For large adductor muscle for keeping vales closed
How deep of a browser is Solen
Deep
What is the shell (Solen)
Elongated and the valves not completely close
What does a large palatial sinus mean (Solen)
Long siphons
Unornamented and streamline (Solen)
Enable it to move easily up and down through the sediment
Small adductor muscle scars (Solen)
No need to open and close the valves in the burrow
Anterior and posterior gapes (Solen)
Indicates that the siphons cannot be retracted into the burrow
Name the nektonic bivalve
Pecten
What is special about pecten and how does it do it
Swimming
Uses a single powerful adductor muscle called monomyarian
How are the valves shaped (Pecten)
The valves are flattened on one side and rounded on the other like an aeroplane
Ribbed, corrugated thin valves (Pecten)
Gives it strength without weight
One flattered valve and one curved (Pecten)
Gives hydrofoil effect to allow movement through the water when swimming
