After seeing hearts everywhere for Valentine’s Day, I started thinking about hearts that aren’t heart-shaped, but rather fist-shaped.

At my last wellness checkup, I had the chance to listen to my heart. Weird, creepy and fascinating are adjectives that come to mind describing that experience. And, as my mind tends to do, I started wondering about this amazing organ, as well as other animals’ hearts.

So where did the heart-shape we associate with Valentine’s Day come from?

There are several answers to this question (and some of them aren’t exactly fit for this article) but the most interesting explanation I found is that heart-shaped seeds from the silphium plant were an ancient form of birth control.

Male vs. female hearts

The human heart typically beats more than 100,000 times a day, with a resting heart rate of 60-100 beats per minute.

On average, a woman’s heart rate is about eight beats faster than a man’s. That is because a woman’s heart is smaller and needs to pump faster to deliver the same amount of blood.

Newborns, however, have the fastest heartbeats, averaging up to 190 beats per minute.

Every minute, the heart pumps about 1.5 gallons of blood out to the rest of the body in a day’s time, which equals about 2,000 gallons of blood sent out into cells and tissues.

Recently on my way to work, the radio station played our national anthem and I had to drive one-handed while I placed my right hand over the left side of my chest. I have done this my entire life even though I know that is not where my heart is — it’s located behind my breastbone.

I wonder how many people know that fact because every time something is mentioned that’s “heart related” that is where their hands end up — over the left side of their chests. The heart does tilt in that direction and that’s where the strongest heartbeat can be felt.

I have heard people say my whole life that laughter is the best medicine and there is a lot of truth to that saying when it comes to the heart.

Laughing and sneezing

Laughter helps relax the blood vessels so blood can flow easier. When laughing, the heart does not have to work as hard to keep blood flowing.

Laughter also reduces stress and strengthens the immune system.

Recently, scientists have found fossil remains of what they believe was a blind dinosaur.

Its name is Doyuthinkitsaurus. Did you laugh? You’re welcome!

The custom of saying “bless you” after someone sneezes started with the belief that the heart briefly stops because of the force of the sneeze.

The heart continues beating when someone sneezes, but its rhythm may change momentarily. That’s good news for me, because I can never just sneeze once.

Did you know?

Heart attacks occur more often on Monday than on any other day of the week, due to the body’s circadian rhythm. They are also common in the morning, because stress hormones are at their highest levels. I knew there was a reason I don’t like Mondays!

The structure of animal hearts varies as mammals, birds, and crocodilians have four-chambered hearts, while most reptiles and amphibians have three-chambered hearts, and fish have two-chambered hearts.

Interestingly, crocodilians have valves in the heart that stops blood flow from the hearts and lungs, and allows it to circulate through the bodies, which enables them to “hold their breath” underwater for over seven minutes.

The hummingbird’s courtship display sends his heart racing! His heartbeats increase to a staggering 1,200 beats per minute while trying to impress the female.

Earthworms have five “pseudo-hearts,” called aortic arches, which wrap around its esophagus. They do not exactly pump blood but rather squeeze vessels to circulate blood in their bodies. Earthworms absorb oxygen through their moist skin, so they do not need an honest-to-goodness heart to circulate oxygen.

After a giant meal, a python’s heart enlarges by about 40 percent, as fatty acids are absorbed from its feast. This helps speed up digestion, but it will still take several weeks.

While their hearts are not unusually large for their body size, they are functionally quirky.

The giraffe’s heart is not unusually large for its body but the left ventricle has the difficult job of pumping blood uphill at least six feet to its head, so that side of its heart is over three inches thick, while the right ventricle only has to send blood to the nearby lungs, so that side is only about a half-inch thick. This asymmetry of the heart is why they do not get dizzy when they stand up.

Don’t be ‘cold-hearted’

To call a person cold-hearted or heartless would be an insult, but for some animals it is the perfect compliment.

Ocean creatures such as sea stars, sea cucumbers, corals, and jellyfish have existed millions of years without hearts at all.

An octopus has three hearts, two that pump blue, copper-rich blood to its gills, and a larger heart that circulates blood throughout the rest of its body. The molecules that carry oxygen — called hemocyanin — contain copper. Human blood is red because the molecules that carry oxygen — called hemoglobin — contain iron.

Zebrafish can grow back heart tissue since they can regenerate their heart in just two months, even after 20 percent of the muscle is damaged.

The wood frog manufactures a blend of “antifreeze” made of its own urine (stored in its blood) and glucose from its liver, which prevents its blood from freezing even as the rest of its tissues are frozen. The frog shuts down — its heart stops beating, lungs and other organs cease, and up to 60 percent of its body is frozen solid until the spring thaw.

Scientists have noted that the frog’s heart resumes beating even before ice in the body has completely melted, and pulmonary respiration and blood circulation are restored soon thereafter. This species found a “cold-hearted” way to outsmart winter!

During our Creepy Crawler class for preschoolers, we froze our gummy frog in a block of ice hoping that when it thawed out, no damage was done to the frog. And, to our relief, our frog had not suffered any from being frozen.

I know it’s a very simple explanation regarding how wood frogs survive the winter, but the preschoolers were impressed.

For now, I guess I will have to stick to hats, gloves, and heated car seats!

Jeannie Carl is a naturalist at the Carbon County Environmental Education Center in Summit Hill. The center rehabilitates injured animals and educates the public on a variety of wildlife found in the area. For information on the Carbon County Environmental Center, visit www.carboneec.org.