We’ve all heard about creatures with extra eyes, but what about animals with extra hearts? It might sound like something out of science fiction, but in nature, multiple hearts are surprisingly real — and incredibly useful. While most animals get by just fine with one, there are some that have evolved with two, three, or even more to help them thrive in extreme environments.

Here are five remarkable animals that have more than one heart — and the fascinating reasons why.

Кальмары

Squids: Triple-Hearted Swimmers of the Deep

Squids are part of a group of marine animals called cephalopods, and they come equipped with not one, not two, but three hearts. Each has a unique function: two branchial hearts pump blood to the gills, while the third, called the systemic heart, pumps oxygenated blood to the rest of the body.

This complex circulatory system helps squids power their agile, high-speed swimming and survive in deep ocean waters. Oh, and fun fact: their blood is blue, due to a copper-rich molecule called hemocyanin — great for oxygen transport in cold, low-oxygen environments.

Осьминоги

Octopuses: Masters of the Ocean With Three Hearts

Like squids, octopuses also have three hearts — a trait they share as fellow cephalopods. Two of the hearts handle oxygen exchange by sending blood to the gills, while the third circulates oxygenated blood throughout the body.

And here’s the twist: when an octopus swims, its main systemic heart actually stops beating — which is why they prefer crawling to conserve energy. Octopuses also have blue blood and an advanced nervous system, making them one of the most intelligent invertebrates on the planet.

Дождевые черви

Earthworms: Five «Hearts» That Keep Them Moving

Earthworms are often said to have five hearts — but technically, they have five pseudohearts. These aren’t true hearts in the way humans have them, but rather muscular blood vessels that pump fluid throughout the worm’s long, segmented body.

These pseudohearts are essential for circulation, especially since earthworms breathe through their skin. Staying moist is critical for their survival, and their unique circulatory system helps maintain this moisture balance underground, where they live and thrive.

Миксиновые

Hagfish: Four Hearts, One Creepy Creature

The hagfish may look like a slimy sea serpent, but it’s actually a jawless fish with a seriously unusual body. One of its strangest features? It has four hearts.

One acts as the primary pump, while the other three assist with circulation. This system allows hagfish to maintain blood flow even under low-oxygen conditions — handy for an animal that feeds on rotting carcasses at the bottom of the ocean. Though not the most glamorous of creatures, their cardiovascular setup is truly impressive.

Тараканы

Cockroaches: One Heart, 13 Chambers

While it’s a myth that cockroaches have 13 separate hearts, their one heart is anything but ordinary. It contains 13 chambers arranged in a linear sequence — far more than the human heart’s four chambers.

This multi-chambered design provides extra resilience. If one chamber fails, the others keep the system going, helping cockroaches survive trauma that would kill most other animals. No wonder they have a reputation for being nearly indestructible.

Why Multiple Hearts Matter

Having more than one heart isn’t just a biological oddity — it’s a survival advantage. Whether it’s improving circulation in deep-sea environments, maintaining hydration underground, or withstanding physical stress, multiple hearts help these animals thrive in ways humans can only dream of.

Next time you think one heart is enough, remember: in nature, sometimes more really is better.