On November 3rd at Zoo Basel, two Cotton-top Tamarin twins came into the world. As is customary with Cotton-tops, the mother and father alternate duties in caring for their new babies. Sometimes, both twins can be seen atop Dad's back, while at other times, Mom will shoulder both babies. Still at other times, it's one baby for each parent. When it's time to eat, of course, dad hands the kids off to Mom for suckling.

Photo credit: Zoo Basel

As these new twins get older, even their siblings will help to carry them. Older siblings play an important role in rearing young tamarins in the wild. They constantly monitor the environment and sound a high pitched whistle to alarm the group if any threats should arise. At birth, Cotton-tops weigh about 45 grams, compared with mom's impressive 600 grams.