Armpits may be a ticklish place for humans, but for manatees (Order: Sirenia), armpits are good for nursing young! Manatees are mammals and nurse their offspring with mammary glands that are located under the pectoral flippers for over a year.
Sketch and fact contributed by Karli Chudeau
Source: Berta, A. (2012). Diversity, Evolution, and Adaptations to Sirenians and Other Marine Mammals. Return to the Sea: The Life and Evolutionary Times of Marine Mammals. Berkeley, CA: University of California.