Flashcards in Brachiopods Deck (15):
What time period
Cambrian, widespread and dominant in palaeozoic, still alive today but losses in Permian extinction and Triassic
Composition of shells?
Chitin and calcium phosphate
Describe morphology of a Brachipod
Bilateral symmetry of valves, symmetrical if centrally bisected, valves uneven size, pedicle larger that brachial, pedicle may be present from foramen, attachment. Brachial valve contains lophophore
What is the lophophore?
Fluid filled set of filaments lined with cilia that generate currents to enable food particles to be trapped
How does Brachipod shell form?
Shell secretes by soft tissue of the mantle
How do Brachipods feed?
All are filter feeders, feed via lophophore, fluid filled, lined with cilia, beat to generate currents, brings in fresh water and removes wasted time as bet to trap particles passed down groove to mouth, separate water already filtered from fresh via fold in edge of the shell
How do Brachipods open and close valves?
Open valves to let fresh water in, by contracting diductor muscles, attached via cardinal processor brachial valve and central part of pedicle valve. To close adductor muscles contract, attached to central parts of both valves leave muscle scar
How are Brachipods adapted to turbulent water?
Large pedicle opening for attachment
Strongly ribbed valves
Thick heavy shell
How are Brachipods adapted to quiet water?
Median fold or suculus to separate currents
Extension of valves to form wings
Smooth if weakly robbed
No pedicle opening
How are Brachipods adapted to soft muddy substrate?
Valves with large flat resting area
One margin upturned to ensure shell remains out if sediment for feeding
How are rhynconellids adapted?
Ordivician to recent, abundant in Mesozoic a strophic curbed hinge, short, strongly ribbed, small pedicle foramen, zigzag commisure, strong fold and sulcus
How are spiriferids adapted?
Ordovician-Jurassic Strophic hinge, long, winged, fold and sulcus, spiral lophophore support, sessile, not attached common in Carboniferous
How are productids adapted?
Devonian to Permian
Wide geological range, semicircular shell, thick strophic convex pedicle valve brachial valve is flat radiating ribs, hollow tubular spines