Arthropods

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 COMMENTS:

• Bilaterally symmetrical, primitively coelomate,Segmented protostomes.

•Coelom reduced to the portions of the reproductive & excreatory systems.

•Body segments primitively associated with one pair of jointed appendages.

•Body divided into two or more tagmata

(regions):

-In mandibulates a head, with sensory

and feeding functions, and trunk, often

subdivided into a thorax (locomotory) &

abdomen (digestive & respiratory functions).

-In chelicerates a prosoma, with feeding

& locomotary functions, and an opisthsoma,

with digestive & respiratory function.

•Exoskeleton typically chitinous (α-chitin)

• Digestive system is complete with large

stomodeal & proctodeal region lined by

chitin in between it's midgut

•Sense organs include sensillium & compounde eyes Brain tripartite.

•Cardiovascular system (open) in which haemolymph is pumped by a heart.

•Excreatory system includes saccular excreatory organs & Malphigian tubules.

•Generally diocious, internal fertilization.




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