The Differences Between Shark & Pig Hearts

Heart Chambers

• The heart chambers are the most noticeable difference between shark and pig hearts. Sharks have two chambers in their hearts. Blood is pumped to their gills and then their tissues, then carried back to the heart. Pigs, however, have four chambers and two circulatory circuits. Their hearts pump blood to the lungs first, where the blood is oxygenated, and then returns to the heart. Blood then recirculates through the heart and is pumped to the rest of the body.

Location and Size

• Like many other fish, a shark's heart is located in its head. A pig's heart, however, is located in its chest, similar to a human's heart. Sharks have small hearts proportional to their body size, while a pig's heart is relatively large. The small size of a shark's heart keeps its circulation slow and blood pressure low. Conversely, pigs have circulation and blood pressure rates very similar to humans and can even develop high blood pressure problems.

Heart Rate

• A pig's heart rate is relatively stable, averaging about 70 beats per minute. A shark's heart rate greatly varies. Large and adult sharks have slower heart rates than small and juvenile sharks. A shark's heart rate is also affected by temperature and pressure. Sharks living in cold water have lower heart rates. Because many sharks migrate throughout the year, there is great variability in an individual shark's heart rate.

Shape

• Shark hearts are s-shaped tubes, while pig hearts are more triangular. The ventricle comprises the base of the shark heart with a thin atrium attached to the top of the ventricle. The ventral aorta, the shark's major blood vessel, extends out of the top of the heart. A pig has two ventricles at the broader base of the heart and two atria at the slimmer top of the heart.