ONYCHOPHORA, TARDIGRADA & Arthropod origins ( Onychophora study images;
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- arthropod-like: cuticle must be molted; reduced coelom; spacious hemocoel (open circulatory system) with a muscular heart; fore- & hind gut lined with cuticle; respire with trachea/spiracle system (independent evolution); large brain; cleavage not spiral
- arthropod-like: cuticle must be molted; no circular muscle layer, discrete muscles attach to cuticle; reduced coelom; spacious hemocoel (but no heart, likely due to small size); fore- and hind-gut lined with cuticle; form of sensory setae; cleavage not spiral
Copyright (c) 2007 by A. Richard Palmer. All rights reserved.
(revised Jan. 28, 2007)