Thursday, February 16, 2012

Labs 05 and 06 - Mollusca

In these labs students examined live and preserved specimens of the main molluscan groups.  The goal of the labs was to do a comparison of the adaptive modifications that different molluscan groups have gone trough relative to the hypothetical ancestral mollusc (HAM).  The main features  to observe were visceral mass, mantle, foot and shell.  In live snail specimens the radula was observed in action.  There were also prepared mounts to observe the radula at the microscope.

Among cephalopods, the only representative observed was a preserved specimen of a squid.

The groups considered were:


Representatives of Polyplacophora
(from Chilebosque forum)
Micrograph and diagram of a chiton's radula
( -

GASTROPODA (Snails, limpets, slugs)

Miscellaneous representatives of Gastropoda
Upper row: Cone, marine slug, banana slug
Lower row: Cowrie and three land snails

Micrographs of snail radulae
left; right
(for details of the anatomy of the gastropod radula click HERE)

Live specimens
Live gastropod specimens observed in the lab
Left: right after the lab session.  Right: 24 hours later

BIVALVIA (Scallops, oysters, mussles, clams)

Representatives of bivalvia
Top row: A scallop, a live scallop, a giant clam
Bottom row: A mussel, oysters, a razor clam
Some freshwater clams ("mussels") from Eastern North America
Top row: Rock Pocketbook, Plain Pocketbook, Wartyback, and Paper Pondshell
Bottom row: Elktoe, Pistolgrip, Rainbow, and Mucket
(Photos from the Illinois State Museum)

Live specimens
Freshwater clams available in the lab, most likely Spikes (Elliptio dilatata)
Top: Detail of an individual
Bottom: left, individuals "planted" in gravel; right, after allowed to wander for 24 hours

CEPHALOPODA (Octopuses, squids, cuttlefishes, nautili)

Representatives of Cephalopoda
Top: Octopus and squid
Bottom: Cuttlefish and nautilus


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