The animals' heart, great and small

The fairy fly, a tiny insect as thin as a sheet of paper, holds the title for having the smallest heart in the world. To observe its heart, a microscope is required despite its minuscule size. Contrary to its name, the fairy fly is actually a wasp. Moving on to a larger yet equally remarkable heart in the Animal Kingdom, the zebra fish possesses a fascinating ability. With hearts measuring only about 0.4 inches in diameter, zebra fish have the power to regenerate their hearts if they become damaged or encounter any issues. While human hearts continuously strive to replace cells and repair heart tissue, they pale in comparison to the regenerative capabilities of zebra fish hearts. Now, let's shift our focus to cockroaches. Human hearts consist of four chambers, each with its own designated function. Without all four chambers working properly, the heart cannot function effectively. On the other hand, a cockroach's heart boasts an astonishing 12 to 13 chambers, arranged in a row along the length of its body, measuring approximately 1.5 inches. These chambers operate independently, powered by different muscles. Consequently, if any of these chambers are affected, the cockroach may not even notice, as it can often survive without all of its heart chambers functioning optimally. In contrast, a hummingbird's heart can beat up to 1200 times per minute. While a human athlete's heart may reach a maximum speed of 220 beats per minute, the hummingbird's heart, despite being one of the smallest in the world, is relatively large compared to its overall body size, accounting for approximately 2.5% of its total body weight. Interestingly, the blue-throated hummingbird's wings flap up to 15 times per second, a movement too rapid for the human eye to perceive. This impressive speed is supported by an even faster heart rate, with the hummingbird's heart beating up to 21 times per second.

The emperor penguin is not just any ordinary penguin species. Contrary to popular belief, they do not have a crown on their heads. These fascinating creatures are exceptional swimmers, capable of diving deeper than any other bird, reaching depths of up to 700 feet. What's even more impressive is their ability to stay submerged for up to 18 minutes at a time. As they search for food, their hearts play a crucial role. Weighing around 5 ounces, their hearts are relatively slow when in the water. In fact, an emperor penguin can reduce its heart rate to a mere 15 beats per minute. This allows the penguin to conserve energy and oxygen, using only what is necessary for its deep-water hunting expeditions.

Heart size tends to be proportional throughout the animal kingdom, with most organs weighing approximately 6% of an animal's body mass. However, there are variations. For instance, dogs and wolves have larger hearts, accounting for about 8% of their total weight. On average, a dog's heart weighs around 20 ounces. Interestingly, if a human heart were to accumulate fat, it would quickly become problematic. However, for a python, this is a positive sign. After a large meal, a python's heart can increase in size by up to 40%. Considering that pythons can weigh as much as 250 pounds, this is quite significant. The increase in heart size is primarily due to the absorption of fatty acids from the meal, which aids in digestion. Although it takes days for a python to fully process a single meal, their blood becomes saturated with fatty acids, causing it to change color and consistency, sometimes resembling milk.

Now, shifting our focus to the other end of the spectrum, we encounter the blue whale, which possesses the largest heart in the animal kingdom. This colossal heart is approximately the size of a bathtub and outweighs the average gorilla. It comes as no surprise, considering that blue whales are among the largest creatures to have ever existed. Regardless of their size, these magnificent animals rely on their massive hearts to sustain their immense bodies.

Most animals typically have only one heart, but this rule does not apply to all creatures. Take octopuses or squids, for example, which possess three hearts. This unique system allows two of their hearts to pump blood to the gills, ensuring an adequate oxygen supply in their bodies. The third heart, on the other hand, is responsible for circulating blood throughout the rest of their body. Interestingly, some animals do not have hearts at all. However, this absence of a heart does not necessarily hinder their well-being. Jellyfish, starfish, and corals, for instance, lead quite fulfilling lives even without this vital organ. In the case of starfish, they don't even have blood, which may explain why they do not require a heart.

No compilation of fascinating facts would be complete without mentioning some intriguing details about the human heart. Contrary to popular belief, you don't need to consult Google or an anatomy book to determine the size of your heart. Simply clench your fingers and make a fist – that's approximately the size of your heart. This incredible organ plays a crucial role in maintaining the overall functionality of our bodies. It beats approximately 105,000 times each day, ensuring the continuous circulation of blood and the delivery of oxygen and nutrients to various tissues. Have you ever seen a cartoon character whose heart seems to leap out of their chest? While it may seem like the sound of a beating heart is caused by the organ physically touching the surrounding tissue, it is actually the result of the opening and closing of heart valves. These valves act as small doors within our hearts, ensuring the proper flow of blood from one side to the other. Our lungs, although not identical, are closely related as siblings. Interestingly, our heart plays a significant role in the size and weight distribution of our lungs. Due to the positioning of our heart, our right lung is slightly larger and tends to weigh more. This is because our heart tilts slightly to the left, creating a small indentation in our left lung known as the cardiac impression. While the right lung may be larger, it is also slightly shorter to accommodate the space required for the liver. This intricate relationship between our heart and lungs highlights the interconnectedness of our vital organs and the remarkable adaptations that occur within our bodies. Speaking about the positioning of our heart, it is not as far on the left side as we tend to believe. In fact, it is mostly centered with just a slight inclination towards the left. However, individuals with dextrocardia are born with their heart positioned on the right side of their chest. While this condition alone is not problematic, it often coincides with other diseases that can have severe effects on both the heart and other organs. Please note that most heart attacks tend to occur on Mondays, although the exact reason behind this phenomenon is still a topic of debate among scientists. It is believed that the stress associated with starting a new work week or the disruption in our sleep-wake cycle could be potential factors. As we tend to sleep more during the weekend and wake up earlier on Mondays, it is possible that these changes may be detrimental to our heart health.

Our heart started beating approximately four weeks after we were conceived, and it continues to do so until the end of our lives. Although it may grow weaker as we age, the heart does not tire easily. Considering the responsibilities it carries out, it is an incredibly resilient organ. To illustrate its strength, try an experiment by squeezing a tennis ball in your hand. The force exerted by your beating heart is equivalent to this pressure, occurring approximately 100,000 times each day. It is highly likely that you will lose count before even completing the task. However, in certain cases, the energy required to keep our hearts pumping becomes unstable. This is why pacemakers were invented. These small generators are implanted inside the human body and help stabilize abnormal heart rhythms. The first-ever pacemaker was implanted in a woman named ARA lson in 1958. Remarkably, she lived until the age of 86, and her cause of death was unrelated to her heart condition.