MOLLUSCA: Diversity III (Mollusca study images; |
a) body plan is highly modified for a burrowing, filter-feeding mode of life:
b) two shells joined by flexible ligament (tension or compression); mantle edge fuses to shell margin & links to adductor muscles
c) foot is highly modified for burrowing (except attached or swimming species); burrowing involves both shell and foot
d) 1 pair ctenidia; may be either:
both have compound latero-frontal cilia for particle capture
e) most produce byssal threads as larvae; some still do as adults
f) sexes are separate; most have free-swimming trochophore & veliger larval stages
g) classification still hotly debated; 4 Subclasses: Paleotaxodonta, Pteriomorphia, Heterodonta, Anomalodesmata (based on type of shell hinge teeth, form of ctenidia, adductor muscle form)
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Copyright © 2002 by A. Richard Palmer. All rights reserved.
(revised Mar. 6, 2002)