304 ^W£ ANIMAL KINGDOM 



Nauplius eye 



1st a-iitcnna- 

 2nd a.nt;enn.a.--~| 



Mandiblcz. and 

 1st m.a>cillsL 



2-nd max ill a.- 

 and max II 1 ipcd 



1st a.ntenna 

 2nd antenna: 



•Trun>[- 

 limbs 



1st a.Tit(Z.nna 



Figure 16.13. Additional orders of small Crustacea. A, Order Copepoda. B, Order 

 Ostracoda, with a hinged carapace enclosing head and body. C, Order Cirripedia, the 

 barnacles, attached by an enormous first antenna, with the body enclosed in calcareous 

 plates. (From various sources.) 



Mysidacea.. 





•^Decapod- 



Is opod-a. 



Figure 16.14. Some of the orders of the subclass Malacostraca. (The first three are 

 after Borradaile, et al., the fourth after Parker and Haswell.) 



The Malacostraca are divided into nine orders, of which five will 

 be mentioned here (see the appendix for all of them). The Mysidacea 

 (Fig. 16.14) are abundant, delicate, shrimp-like animals living near the 

 bottoms of shallow seas and arctic fresh water. They usually rise into 

 the upper water as plankton at night. The Euphausiacea are similar, 

 living deep in the open ocean by clay and coming near the surface at 



