lab/lecture 10: mollusca bivalvia Flashcards
(17 cards)
Describe (Class) Bivalvia.
Marine mollusks with two hinged calcareous valves; no radula; most use gills for filter feeding and respiration; symmetrical between valves.
Describe (Subclass) Palaeotaxodonta.
Earliest bivalves; protobranch gills, equivalved aragonite shell, taxodont dentition; includes small deep-water clams like Nuculoida.
Describe (Subclass) Cryptodonta.
Infaunal bivalves with aragonite shells; protobranchiate gills; few or no hinge teeth; includes Solemya.
Describe (Subclass) Pteriomorpha.
Byssally attached or cemented bivalves; variable musculature, dentition, and shell composition; includes scallops, oysters, inoceramids.
Describe (Order) Arcoida.
Ark shells with long taxodont hinges; thick, ribbed shells; live in rock crevices; equivalved or trapezoidal shells.
Describe (Order) Mytiloida.
Mussels; byssally attached; equivalved, elongate shells; almost toothless hinge; common in intertidal zones.
Describe (Subclass) Palaeoheterodonta.
Mostly Paleozoic; equivalved aragonite shells; few hinge teeth; includes freshwater Unionoida and Trigonioida.
Describe (Subclass) Heterodonta.
Triassic–Recent; heterodont hinge with cardinal and lateral teeth; includes most living clams.
Describe (Order) Veneroida.
Active burrowing bivalves with heterodont teeth; short siphons; includes many familiar clams.
Describe (Order) Myoida.
Deep burrowers; thin shells; long siphons; degenerate hinge with one cardinal tooth.
Describe (Order) Hippuritoida.
Rudists; thick coral-like shells; dominated Cretaceous reefs; some shells reached 2 meters.
Describe infaunal burrowers.
Bivalves with equivalved or elongate shells, strong pallial sinus, long siphons; use foot to dig.
Describe byssally attached bivalves.
Byssal attachment in bivalves refers to the use of strong, silky threads, called byssal threads, to attach themselves to a solid surface
Describe cemented bivalves.
bivalves that permanently attach themselves to a hard substrate using their shell material as a cement
Describe free-lying bivalves.
Rest unattached on sediment; thick convex lower valve, flat upper valve; sometimes spines.
describe taxodont vs heterodont dentition
taxodont (rows of numerous subparallel teeth of a similar size), heterodont (two or three teeth below the umbo)
describe infaunal vs epifaunal
Infaunal organisms live within the sediment of a body of water, while epifaunal organisms live on the surface of the substrate
