In stark contrast to humans, otters have successfully achieved gender equality when it comes to pockets. Both female and male otters have baggy portions of loose skin under their forearms that they can use to store various items. These pockets are often used to store food for later, but are also home to rocks that otters use to open up mollusks and clams. Otters will use these rocks to smash their shelled prey either on a stone surface or by laying the rock on their chest and smashing the shell down on the rock. Otters will even reuse the same rock over and over again, leading some zookeepers and researchers to suggest that otters have a “favorite” rock that they like to keep on them.

Sketch contributed by Nicole Korzeniecki.

Fact contributed by Adrian Perez

Sources:

https://oceantoday.noaa.gov/seaotteranatomy/

Hall, K.R.L. and Schaller, G.B., 1964. Tool-using behavior of the California sea otter. Journal of Mammalogy, 45(2), pp.287-298.