Pictured is the heart and pericardium of a juvenile male fox squirrel. The organ has a height of 25.6 ± 0.5 mm, a width of 17.8 ± 0.5 mm, and a mass of 3 ± 0.5 g. It looks like a miniture human heart, but although the squirrel's heart has about the same mass proportions to body mass as a human, to support the energetic life of a tree squirrel, it beats an average of 259 times per minute (Koprowski, 1994), several times faster than a human heart.
Works Cited:Koprowski, J. L. (1994). Sciurus
United States, South Dakota,
Image Date: 2008APR18
Image Species: Sciurus niger rufiventer
(EXIF Info is accurate – stamped in UTC).
Web Page and Pictures By Hannah Leitheiser