Animals come in a dizzying range of shapes and sizes, from tiny ants to massive elephants and blue whales (the largest fauna that has ever lived on Earth [PDF]). With an estimated 8.7 million species of plants and animals sharing the planet, it's a sure bet that we'll find some of them ugly, weird, or scary-looking. Here’s a list of a few terrifying creatures that might haunt your dreams.

1. Basking Shark

Rebecca-Belleni-Photography Via Getty Images

The basking shark (Cetorhinus maximus) might look scary, but it's actually the epitome of Finding Nemo’s shark mantra: “Fish are friends, not food.” According to Oceana, these beasts are the second largest fish in the world, bested only by the whale shark; they weigh up to 10,000 pounds and grow to 45 feet. That’s longer than a telephone pole or a London bus, or six Shaquille O'Neals standing on top of each other. Thankfully, they're harmless. Basking sharks mainly eat zooplankton by swimming with their mouths wide open, and they like to sun themselves on the surface of the ocean. So the next time you see a gaping shark coming at you—and if it is, in fact, a basking shark—you have nothing to worry about.

2. Aye-aye


javarman3 Via Getty Images

The aye-aye (Daubentonia madagascariensis) is equal parts charming and scary. With big glowing eyes, long fingers, and bat-like ears, this lemur native to Madagascar is the world’s biggest nocturnal primate. According to the World Wildlife Fund, they're the sole species in their taxonomic family, meaning no other animal is closely related to them. Like bats, they use echolocation to find food: With a technique called percussive foraging, they use their long fingers to tap on hollow trees and find where insect larvae are located. Unfortunately, aye-ayes are extremely endangered: According to some local folk beliefs, they are symbols of death, and people often kill them.

3. Giant Golden-Crowned Flying Fox

Found in the Philippines, the giant golden-crowned flying fox (Acerodon jubatus) is the world's largest bat, with a wingspan of approximately 5 feet 6 inches. That’s wider than the average American adult is tall. Luckily, they're nothing like the vampire bats that feed on the blood of mammals (and occasionally birds). Giant golden-crowned flying foxes are herbivores and harmless to humans. They are endangered, however, due to poaching and destruction of their habitat—which is bad news for the environment. These fruit-eating bats help propagate new plants when they poop out the seeds of previous meals. Organizations like Bat Conservation International are working to protect these charismatic creatures.

4. Shoebill Stork

Kesu01 Via Getty Images

Imagine taking a peaceful walk around east-central Africa and suddenly seeing this massive bird staring back at you like it wants to kill you. The shoebill stork (Balaeniceps rex) isn't actually a stork—they're actually more closely related to pelicans. Shoebills grow up to 5 feet tall with an impressive 8-foot wingspan. Their feathers are often blue-gray with a white underbelly; their large bills allow them to decapitate their favorite food (lungfish); and they make a chattering noise when they see other shoebills. As scary as these creatures look, they're harmless as long as you’re not a fish or crocodile, according to the National Audubon Society. They tend to be solidary birds and their biggest threats come from poaching and demands of the black market. And that creepy stare they throw your way? It's how they activate their binocular vision.

5. Southern Cassowary


BirdImages Via Getty Images

Speaking of creepy birds, how about one that looks like it should be a dinosaur? Southern cassowaries, native to northern Australia, have long, sharp claws and a helmet on their heads. Adult southern cassowaries (Casuarius casuarius) can weigh between 121 and 157 pounds, so it’s not surprising that they're flightless. That doesn’t stop them from leaping up to 7 feet into the air or running up to 30 miles per hour. If they feel threatened, they make themselves look bigger, and if that doesn't defuse the threat, they'll attack by kicking and stabbing with their giant claws. In 2019, a man in Florida was killed by his pet cassowary after he fell into its enclosure.

But you'll probably hear the southern cassowary well before you see it; they emit low, deep roars when they sense danger.

6. Star-Nosed Mole

Myrrha Via Getty Images

While the babies are sort of adorable, adult star-nosed moles (Condylura cristata) look like space creatures with face tentacles. The 22 "arms" of their star-shaped noses are packed with sensory receptors that are much more sensitive than the human fingertip, allowing these nearly-blind moles to navigate their environment. They spend most of their time burrowing underground with their enormous claws and consuming insects. According to National Geographic, they're the animal kingdom's fastest eaters and can gobble up a bug in a quarter of a second. They can be found throughout eastern North America and help maintain their habitat's health by aerating soil and plant roots with their burrowing. They are also semiaquatic and have been recorded playing in snow. You do you, star-nosed mole!

7. Crocodile Monitor

Cursed Senses Via Getty Images

Weighing an average of 44 pounds, crocodile monitors (Varanus salvadorii) are large lizards native to New Guinea that like to chill out in trees. They're often considered to be one of the longest lizards in the world, with some growing to 8 feet long; a few have measured over 10 feet. Most are black with either green or yellow spots. Some people keep them as pets, but because of their huge size, they need massive enclosures that don't always keep them captive (in 2017, one escaped its home in California). Crocodile monitors are the apex predators in their environment, hunting and devouring a varied buffet of small mammals, birds and their eggs, reptiles, and amphibians.

8. Portuguese Man O' War

Darieus Via Getty Images

The Portuguese man o’ war (Physalia physalis) looks like an alien straight out of the latest sci-fi blockbuster and is a perfect reminder to not mess with the ocean. These sea creatures aren't actually jellyfish, but siphonophores—a type of colonial organism made up of different, smaller organisms. According to Oceana, they're incredibly venomous, and some of their tentacles can grow to 160 feet long. They often hang out in groups of up to 1000 individuals, which explains why, in 2020, a North Carolina beach town warned vacationers to watch their step when a vast number washed up on the sand. While Portuguese man o' war stings—which paralyze the small fish they eat—are rarely fatal to humans, they still hurt like the dickens.

9. Giant Hatchetfish

SEFSC Pascagoula Laboratory, Wikimedia Commons // Public Domain

"Giant" is kind of a misnomer here: At about 4 inches long, the giant hatchetfish (Argyropelecus gigas) is much smaller than the other animals on this list. They're shaped somewhat like a hatchet and eat small fish. Like other denizens of the bathypelagic zone, where no sunlight filters down, hatchetfish create their own light via bioluminescence. Their bodies contain light-producing organs called photophores—making them basically underwater fireflies. They lure their prey with their light while the rest of their body remains camouflaged in the dark water, then snatch up their food before it can even comprehend what's happening.

10. Goliath Bird-Eating Spider

Some people find all spiders creepy, but this colossal tarantula (Theraphosa blondi) surely takes the cake. The Goliath bird-eating spider's dark brown, furry body can measure over 4 inches with legs that can be 11 inches long. These natives of northern South American rainforests are not only the biggest tarantulas in the world; they can snack on any organism smaller than they are, including birds, lizards, frogs, and even bats. They ambush their prey, hiding under rocks until they strike. When threatened, the Goliath bird-eater makes a loud hissing sound by rubbing their front two legs together. We just hope a few tarantula hawks can keep them far away from us.