15 Weird Animal Facts: Cows Have BFFs, Cats Can't Taste Sweet

Male mosquitoes feed on nectar, but only female mosquitoes bite humans and animals. They need the protein in blood to develop their eggs. So next time you're swatting, blame the maternal instinct.

Two hearts pump blood to the gills, while one heart pumps it to the rest of the body. When they swim, the heart that serves the body actually stops, which is one reason octopuses prefer crawling over swimming.

Vampire bats have heat sensors on their noses that help them locate areas of their prey where blood flow is close to the surface. It’s how they make their bite as efficient as possible.

As a defense mechanism, the horned lizard can squirt blood from ducts near its eyes. The blood can confuse predators or even irritate their mouths.

Electric eels aren't true eels but fish, and they can release up to 600 volts of electricity—enough to knock down large animals or even humans. It’s a shocking survival tactic.

The platypus is the only mammal besides the echidna that lays eggs. Despite having fur and nursing their young, they produce offspring the reptile way.

Unlike humans and dogs, cats lack taste receptors for sweetness. That explains why your cat ignores your cupcake but goes wild for tuna.

Barn owls eat their prey—like mice and small birds—without chewing. Later, they regurgitate indigestible parts like bones and fur in neat little pellets.

They’re the only birds that can fly forward, backward, sideways, and even hover in place. Their wings beat up to 80 times per second.

Studies have shown that cows form close social bonds and become stressed when separated from their best friends. Their heart rates even drop when they’re reunited.

Sheep aren’t as clueless as they look. They can remember and recognize up to 50 different sheep faces for over two years, and at least 10 human faces.

Horseshoe crabs have blue blood due to copper-based hemocyanin. Their blood is used in medical testing because it clots in the presence of bacterial toxins.

While they look fluffy and white, polar bears have black skin beneath their fur to help absorb heat. Their fur is actually transparent and reflects visible light.

Even though they live in the ocean, whales are mammals and must surface to breathe. If they get stuck underwater for too long, they can drown just like humans.

Rabbits have a one-way digestive system, meaning food goes in one direction only. They can’t vomit, which is why hairballs are dangerous for them.

We created this article in conjunction with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.