672 



Class Crustacea 



Class Chilopoda 



Class Diplopoda 

 Class Insecta 



Class Arachnoidea 



CLASSIFICATION 



acteristics ) ; jaws, hemocoel, trachea, jointed append- 

 ages (arthropod characteristics) (Peripatus) 



Water dwellers; breathe by means of gills; numerous mod- 

 ified appendages; possess head, thorax, and abdomen 

 or fused head and thorax ( cephalothorax ) ( lobster ) 



Flattened dorso-ventrally with 1 pair of legs on each seg- 

 ment (centipedes) 



Segments possess 2 pairs of legs ( millipedes ) 



Air-breathers ( trachea ) ; body divided into head, thorax, 

 and abdomen (grasshopper) 



No antennae; cephalothorax and abdomen only; 4 pairs 

 of legs ( spiders and ticks ) 



Phylum MoLLUSCA ( Shelled animals ) 



Class Amphineura 



Class Pelecypoda 



Class Gastropoda 

 Class Scaphopoda 

 Class Cephalopoda 



Shell, when present, with 8 plates; no tentacles; bilater- 

 ally symmetrical (chitons) 



Bivalve mollusks; tentacles; wedge-shaped foot; usually 

 2 gills (clams) 



Flat foot; tentacles (snails, slugs) 



No gills; delicate tentacles (tooth shells) 



Head and eyes large; foot modified into tentacles ( squids, 

 cuttlefish ) 



Phylum EcHiNODERMATA (Spiny-skinned animals) 



Class Crinoidea 



Class Asteroidea 



Class Ophiuroidea 

 Class Echinoidea 



Class Holothurioidea 



Phylum Chordata 

 Class Cyclostomata 



Class Chondrichthyes 



Class Osteichthyes 

 Class Amphibia 

 Class Reptilia 



Class Aves 



Five branched rays; tube feet without suckers; tempo- 

 rarily or permanently attached; mostly fossils (sea 

 lilies ) 



Five rays indistinct from disk; dermal branchiae (star- 

 fishes ) 



Five flexible rays distinct from disk ( brittle stars ) 



Hemispherical or disk-shaped; no free rays; movable 

 spines ( sea urchins, sand dollars ) 



Long, ovoid, soft body; no rays; cloaca with respiratory 

 tree (sea cucumber) 



Without scales, jaws, or lateral fins; fishlike (lampreys 

 and hags) 



With jaws; 5-7 pairs of gills in separate clefts; cartilag- 

 inous skeletons; placoid scales; paired fins (sharks, 

 rays) 



Bony skeletons; 4 pairs of gills in single cavity covered by 

 operculum; cycloid or ctenoid scales (common fishes) 



No scales; moist skin; pentadactyl; young aquatic (gills); 

 adults terrestrial (lungs) (frogs, salamanders) 



Dry, scaly skin; air-breathers (lungs) (turtles, lizards, 

 snakes ) 



Warm-blooded; wings; feathers (birds) 



