External anatomy of an arthropod.
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<BR><LI> The body of a lobster is segmented.
<BR><LI> The appendages (antennae, pincers, legs, etc), are jointed.
<BR><LI> The body is covered by an exoskeleton made of chitin.
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   The  exoskeleton  requires  them  to  molt  as they grow, in a process
   called ecdysis.