There’s a lot to love about animal hearts!

Hearts are everywhere when Valentine’s Day comes around. Why? People used to think feelings like love came from the heart. But we now know that the heart is a muscle that pumps blood all around the body. Blood delivers the energy and oxygen we need to stay alive.

But not all hearts are the same. Check out some wild differences within the animal kingdom.

HOW MANY?
Most animals have one heart each, but an octopus has three! So do its close cousins, squids and cuttlefish. Some animals, such as jellyfish and sea stars, get along just fine with no hearts at all. They don’t have blood anyway!

HOW SMALL?
The world’s smallest heart belongs to a tiny kind of wasp called the fairyfly. This insect is so small, you’d need a microscope to see its heart.

HOW BIG?
Your heart is about as big as your fist and weighs less than a pound. A giraffe’s heart can be 2 feet long and weigh about 25 pounds! It needs to be that big to pump blood all the way down four long legs and up that long neck to the giraffe’s brain. The biggest heart in the world belongs to the blue whale. It weighs around 400 pounds. That’s about the weight of an adult gorilla!

HOW FAST?
Your heart usually beats between 60 and 100 times per minute. The heart of a tiny shrew beats up to 1,200 times per minute! That’s similar to the heart rate of a hummingbird in flight

HOW DOES IT DO THAT?
The 2-inch-long zebrafish has a huge superpower: If its heart gets injured, the fish can regrow the muscle! Scientists are trying to discover how it does that. Maybe one day they can figure out a way to get a human heart to do that, too!

FUN FACT: A blue whale’s giant heart sometimes beats only twice per minute.