Order COPEPODA 



Thoracic appendages cylindrical; body more or less elongate and 

 usually distinctly segmented 

 Order OSTRACODA 



Body without distinct segmentation and entirely enclosed in a bivalve 

 carapace; with seven pairs of cylindrical appendages 

 Subclass MALACOSTPxACA 



Small or large crustaceans with appendages on abdomen 

 Order MYSIDACEA 



With a carapace over head and thorax; walking legs all biramose 

 Order DECAPODA 



With a carapace over head and thorax; walking legs not biramose 

 Suborder NATANTIA Shrimps and Prawns 



Shrimp'like; pleopods aid in swimming 

 Suborder REPTANTIA Crayfishes 



Lobster- like; pleopods do not aid in swimming 

 Order AMPHIPODA 



Body laterally compressed; no carapace 

 Order ISOPODA 



Body flattened dorso-ventrally; no carapace 



ANNOTATED LIST OF THE ORDERS OF ARACHNIDA 



Order SCORPIONIDA Scorpions 



Elongate, the tail-like abdomen bearing on its end a poisonous sting 

 Order PALPIGRADI Microscorpions 



Minute; spider-like, but with a long, tufted and segmented tail 

 Order PEDIPALPI Whip-scorpions 



First pair of legs much elongated; with or without a long, thread-like tail 

 Order SOLPUGIDA Solpugids 



Head distinct from thorax and with very large, pinching structures 

 Order CHELONETHIDA (or Pseudoscorpionida) False Scorpions 



Tiny, flattened forms, with relatively huge chelae 

 Order PHALANGIIDA Harvestmen or Daddy-long-legs 



Body ovoid; legs very long and slender 

 Order ARANEIDA (or Araneae) True Spiders 



Thorax and head completely fused, and distinct from the abdomen 

 Order ACARINA Mites 



Body ovoid, cephalothorax and abdomen not distinct; legs short 

 Order TARDIGRADA Water Bears 



Minute, usually aquatic; body and legs unsegmented 



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