The names are in Latin because during the middle ages and the renaissance era this was in fact the "global" language educated people spoke - english wasn't always the go-to solution (if it weren't for Latin the obvious go-to solution throughout most of Europe's history would have been either French or German).
Pretty much everyone who studied at a university or a theological institute was able to understand and speak Latin back then no matter where they came from or where they lived, so it was a pretty obvious thing to make the scientific names of all animals in this common global language.
There's even some scientists from the early 1900s that still wrote their species descriptions in Latin (which is quite horrible for modern taxonomists as barely anyone today can actually understand Latin to a degree where they're able to read those things).
Astronomy (another branch of modern science that has it's origins in the same historical time period) has a similar thing going on with naming places/landmarks on other planets and their moons, that's where names like 'Valis marinaris' (= the Valley of the Mariner space craft, a NASA space probe that examined Mars in 1964) and 'Olympus Mons' (= Mount Olymp, the largest volcano in the solar system, it's as wide as Arizona and almost three times the height of Mount Everest) come from.
Edited by Serafine, December 12 2018 - 12:29 AM.