Monkeys are mammals mentioned occasionally in the How to Train Your Dragon Book series.
'Monkey' is a term that can apply to a specific taxon of primates, or a general term for non-human primates. Depending on the classification, 'monkey' may or may not include apes such as gorillas and chimpanzees.
Roughly speaking, monkeys are primates smaller than humans, usually having a tail, and live in tropical and sub-tropical regions around the globe. Most species are arboreal - living in trees - and those that aren't are capable of climbing trees. Monkeys have opposable thumbs to aid in gripping and manipulating items in their environment. Monkeys are largely herbivorous, but also eat insects and flesh, depending on the species.
Monkeys function as references to describe a character or character's actions in the Book series.
In actuality, monkeys are eaten by some cultures or killed for body parts purported to have medicinal powers. They may also be kept as pets or in zoos for public viewing. Monkeys have also been used extensively in scientific research due to their closely similar biology to humans.
Gorillas are mentioned in the Book 1 when describing Dogsbreath the Duhbrain as "a great, big gorilla of a boy."
|“||Hiccup didn't normally stand up to Snotlout, but he couldn't bear to see an animal as proud and dignified as a Sabre-Toothed Driver made to dance about like a monkey.||”|
|— Book 4|
|“||GOBBER, YOU BIG, STUPID, BARBARIAN BABOON, ARE YOU BLIND? SHE FOULED ME!||”|
|— Fishlegs in Book 4|
|“||Toothless D-D-DELICATE, sensitive ... not like YOU, you big, white, gormless mountain gorilla ...||”|
|— Toothless in Book 4|