242 



ANNELIDA AND ARTHROPODA: 



retiring animals usually are scavengers. Although 

 they tend to feed upon decaying plant material, they 

 can become garden pests when feeding on growing 

 plants. 



Sometimes the Diplopoda, Chilopoda, Pauropoda, 

 and Symphyla are grouped in a single class Myria- 

 poda. However, most students of arthropods no 

 longer consider them a natural group. 



CLASS CHILOPODA (Centipedes) 



Diagnosis: head with one pair of antennae and two 

 pairs of maxillae; body long, dorsoventrally flattened; 

 body segments 15 to 181, each with a pair of legs; 

 first pair of legs modified, hook-like, and with a 

 poision duct leading to terminal fang, sexes separate, 

 eggs laid or young born alive; young resemble adults 

 (Figure 14.16). 



Figure 14.16 Class Chilopoda, Sco/openc/ro, a centipede (x 1). 



Centipedes are predaceous, mainly on insects, and 

 usually are found under objects on the ground or in 

 other dark, moist places. Large species may prey 

 upon lizards or mice. Many are venomous, but bites 

 rarely cause man anything more than discomfort. 

 The poison-injecting front legs normally are bent 

 forward and serve for predation rather than for 

 walking. 



CLASS PAUROPODA (Pauropods) 



Diagnosis: head with one pair of three-branched 

 antennae, and one pair of maxillae; body elongate, 

 cylindrical, but minute, length 1/50 to 1/12 inch; 

 body of 11 (sometimes 12) segments and with 9 

 (sometimes 10) pairs of legs; eyeless, whitish forms 

 that resemble millipedes; reproduction with four 

 larval stages and metamorphosis; terrestrial, in damp 

 places under objects on ground surface, or in the soil; 

 believed to feed upon fungi (Figure 14.17). 





Figure 14.17 Class Pauropoda, Pauropus (x 30), and Class Sym- 

 phyla, Scuiigerella, a garden centipede (x 6), below left. 



CLASS SYMPHYLA (Garden Centipedes) 



Diagnosis: head with one pair of antennae, and 

 two pairs of maxillae; body elongate, cylindrical, 1/25 

 to 1/3 inch long; body of 15 to 22 segments and with 

 10 to 12 pairs of legs; eyeless and centipede-like, but 

 centipedes have at least 15 pairs of legs; larva with six 

 or seven pairs of legs, metamorphosis to the adult; 

 active, whitish, terrestrial animals of damp places 

 containing humus; feed upon vegetable matter in 

 the soil, sometimes damage cultivated plants or field 

 crops (Figure 14.17). 



CLASS INSECTA (Insects) 



Diagnosis: body with head, thorax, and abdomen 

 distinct; head with one pair of antennae and mouth 

 parts variously modified for chewing, sucking, or 

 lapping; thorax of three segments, typically with two 

 pairs of wings (also one pair or none) and three pairs 

 of legs; abdomen usually 11 segments, but variable, 

 without legs; reproduction generally with separate 

 sexes (also parthenogenesis), eggs laid (also retained 

 by female), and usually some form of metamorphosis 

 (development also direct); widespread and very num- 

 erous in all habitats, but only a few are marine. 



Insects are arthropods with one pair of antennae, 

 three pairs of legs and three body regions— head, 

 thorax, and abdomen. Simple eyes and compound 



