Last summer, for the 50th birthday of Nenette the Bornean orangutan, one of the oldest in captivity, her keepers at Jardin des Plantes zoo in Paris presented her with a strawberry layer cake crowned with tropical fruit. Adelaide, a short-beaked echidna at Illinois’ Brookfield Zoo, also got a cake when she turned 50 last spring, although her gooey treat was frosted with wax worms. Henry, an Aldabra tortoise with a decade on both dames, celebrated his 60th birthday with a decadent confection made of watermelon, cantaloupe, grapes, kiwi, sweet potato,…