b) the acron and telson (bears the anus) are considered homologous to the annelid prostomium and pygidium

c) lack of motile body cilia throughout phylum supports monophyly

d) all possess a semi-rigid exoskeleton and jointed limbs

b) each body segment has 2 or 4 plates (sclerites): dorsal tergite (=notum), two lateral pleurites (Crustacea and Uniramia only), ventral sternite

c) the cuticle has 3 main layers; thin and flexible at joints:

- epicuticle: protein only; thin, may be waxy in insects; molted
- exocuticle: chitin, proteins (may be tanned) and minerals; molted
- endocuticle: chitin, proteins and minerals; resorbed before molting

d) molting is controlled by ecdysone (hormone); only epi- and exocuticle is shed (includes lining of foregut, hindgut, trachea, gills, and apodemes); endocuticle and 30 - 60% of muscle mass is resorbed!

e) new cuticle is produced underneath the old one before it is shed

f) following a molt, water or air inflates the body to its new size before the cuticle hardens again

g) principle molting fracture planes vary among subphyla

b) the terminal exite= exopodite, the terminal endite= endopodite

c) non-terminal branches include epipodites (an exite) and gnathobases or oostegites in peracarid crustaceans (both are endites)

d) may be uniramous (1 terminal branch) or biramous (2 terminal branches); in uniramous limbs the exopodite is lost (e.g., walking legs of crustaceans and insects)

e) limbs may be phyllopodous (flattened, produce only flap-like motions) or stenopodous (tubular, like a typical walking leg; produce a wide variety of motions like robotic arms)

f) movement is controlled by muscles intrinsic to the skeleton that attach at joint margins or to infoldings of the cuticle (apodemes)

g) stenopodous limb joints often have alternating ball and socket (di-condylic) hinges in adjacent segments