"They live among animals."
Translation:De bor blant dyr.
"Reside" (used more often in Norwegian than in English) versus "live."
No, at least not in the indefinite form. It is explained later in https://www.duolingo.com/skill/nb/Plurals/tips-and-notes:
Single-syllable neuter nouns, such as hus house and dyr animal, often do not change spelling in the indefinite plural.