Bivalves and Brachiopods Flashcards
Time period of Bivalves?
Lower Cambrian to recent
What group are bivalvia in?
They are Molluscs in the group Millasca
Shell size of bivalvia?
Few mm to 1m
Do they have feet and where are they found? Bivalves
Yes! They’re found at posterior end
Where do they live - i.e what water environment? Bivalves
Freshwater and Marine
Do they have any symmetry? - Bivalves
They have a single line of symmetry
How do they keep their shells closed? - Bivalves
They have ligaments which holds their shell together and opens passively - muscular effort needed to hold their shells together.
Why was there a rise in shell burrowing forms?
Driven by the rise of shell crushing organisms, greatly affected gastropods etc
Time period of Brachiopods
Early Cambrian - Recent
Where do they live? Brachiopods
Exclusively marine environments
What do their syphens do? Brachiopods
Their inhalent syphens suck water in where as the exhalent excreet waste.
How do they open and close their shells? Brachiopods
They have an diductor muscle which pulls the shell open and a adductor mucle which pulls the shell closed.
What do their syphens do? Brachiopods
Their inhalent syphens suck water in where as the exhalent excreet waste.
What’s special about the coating of the Brachiopoda shell?
The outershell is covered with a thin periostracum (thin organic coating).
What’s the differences between articulate and inarticulate brachiopods
Articulate brachiopods have toothed hinges and simple opening and closing muscles, while inarticulate brachiopods have untoothed hinges and a more complex system of muscles used to keep the two valves aligned
