Unlike the urban legend that states a Blue whale (Balaenoptera musculus) heart is the size of a small car, their hearts are actually about 400 pounds (181 kilograms), or the size of a small golf cart. New research suggests that the proportion of heart size to body size can vary in mammals depending on their lifestyle and hunting strategies. Mammals who are more active may have a larger heart in comparison to their body size.

Blue whales are the largest animal on the planet (88 feet / 27 meters long), but their heart is only about 0.52% of their total body mass. This may be because there are mechanical limitations on a mammalian heart as large as a golf cart. Another reason for this smaller heart size may be that they don’t pursue their food (krill), as actively as a dolphin (heart is 0.90% of body size), which requires more aerobic exercise to capture their prey.

Sketch and fact contributed by Karli Chudeau

Source: Williams, T.M., Bengtson, P., Steller, D.L., Croll, D.A., & Davis, R.W. (2015). The healthy heart: Lessons from nature’s elite athletes. Physiology, 30, 349-357. DOI: 10.1152/physiol.00017.2015.