TWO MINOR PROTOSTOME PHYLA (Annelida study images;
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a) body of two distinct parts: trunk and large flap-like proboscis
b) have one large coelom and coiled gut with terminal mouth and anus
c) separate sexes; have extreme sexual dimorphism: females may be up to 2m, but males are only 1 - 2mm and live as a commensal inside the female's genital sac!
d) linked to annelids by: annelid cross, paired setae in setal sacs
a) reach large size in vent communities; make long chitinous tubes
b) 3 body regions: i) forepart with tentacles, ii) trunk, iii) large segmented opisthoma (fully segmented coelom; setae in setal sacs)
c) larvae have a complete gut like an annelid worm; lack a gut as adults but possess symbiotic bacteria in tentacles or trophosome
d) separate sexes, method of fertilization unknown
e) linked to annelids by features of opisthoma (segmentation, setae in setal sacs) and trochophore-type larva
Copyright (c) 2004 by A. Richard Palmer. All rights reserved.
(revised Feb. 1, 2004)