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General Zoology Handout
Lab 5
Exercise 11: Eucoelomate animals
Eucoelomate animals have a true body cavity that is completely lined with peritoneum.
Phylum Mollusca: The following terms are typical of molluscs: foot, mantle and
radula.
Class Monoplacophora: bilateral symmetry; single dome-shaped shell and a broadflat foot; radula present; dioecious
###Class Polyplacophora: elongated dorsally flattened body with reduced head;
bilateral symmetry; radula present; shell of eight dorsal plates *** Look at the
Katharina and the Chaetopleura
Class Caudofoveata: wormlike; shell, head and excretory organs absent; mantle with
cuticle and hard scales; oral shield near anterior mouth; sexes separate
Class Solenogastres: similar to caudofoveatas with the exception that there is a long
foot present and most are hermaphrodites
###Class Scaphopoda: body enclosed in a one-piece tubular shell open at both ends;
conical foot; head absent; sexes separate*** Look at the tusk shell
###Class Gastropoda: snails, slugs, conchs and others; asymmetrical bodies, often in
a coiled shell; well-developed head and radula; large flat foot *** Look at the wet
jars of slugs and snails and various shells.
###Class Bivalvia: body enclosed in a two-lobed mantle; dorsal hinge on shell with
two lateral valves; no radula; reduced cephalization; wedge shaped foot; plate-like
gills *** Look at the mussel. You are responsible looking at the diagrams on
pages 172-174, identifying and knowing the following: anterior and posterior
adductor muscles, anterior and posterior foot retractors, mantle, gills, foot,
incurrent and excurrent aperture (canals), stomach, digestive gland, intestine,
goanad, heart (auricle+ventricle), kidney Fig11-5. Sketch and label these in your
lab book. Look at the various shells. On a muscle shell identify: Umbo, Pallial
line, Hinge ligament, Pseudocardinal tooth, Lateral teeth (fig 11-3) and
Periostracum, Prismatic and Nacreous layers (fig 11-4). Look at the
Glochidium demo.
###Class Cephalopoda: squids, nautiloids and octopuses; shell reduced or absent;
head well-developed with eyes and radula; foot modified into arms and/or
tentacles; beak present; siphon (funnel) present Figure 11-14; sexes separate***
Look at the octopus and squid.