ARTHROPODA (II): General features (cont.) (Crustacea study images,
other arthropod study images;
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b) the image is actually a composite of many separate spots of light
c) multiple evolutionary origins seem likely because details of ommatidium form vary among groups
ii) limb-branch gills in crustaceans are typically exopodites or epipodites, and may be thoracic (most common) or abdominal
ii) spiracle/trachea systems occur in most uniramians, some arachnids and a few crustacea (primarily diffusion)
b) most of the primary coelom fuses with the epineural sinus yielding an extensive hemocoel
Copyright (c) 2005 by A. Richard Palmer. All rights reserved.
(revised Mar. 3, 2005)