Long necks often serve multiple functions, as demonstrated here by
Galapágos giant tortoises Geochelone nigra. (a) Use of the
long neck for high browsing is commonly practized by terrestrial
testudines. Based on a photograph in Moll (1986:74-75). (b) Use of
the long neck in establishing dominance. The two tortoises shown in
the illustration were photographed on Santa Cruz Island: the
dome-shelled animal on the right belongs to the native
form G. n. porteri while the saddlebacked animal
at left represents the Española form G. n.
hoodensis. Based on a photograph in Fritts (1984: Fig. 2).