Multiple choice general knowledge math & puzzles At birth the opossum is about the size of a what? Cat Bumblebee Fly Mouse Reveal answer Fill a bubble to check yourself B Correct answer Explanation Opossums are marsupials. At birth, the joeys are extremely underdeveloped and tiny, roughly the size of a honeybee or bumblebee. They then crawl into the mother's pouch to continue developing. They are much smaller than mice at birth.