For some freaky animals, every day is Halloween.

Take sarcastic fringehead fish, which can look pretty darn scary.

Males of this Pacific Ocean species will fight anything that threatens their eggs or territory, and in doing so open their colorful mouths wide in an intimidating display called gaping.

Battles between these 10-inch fish, a type of blenny, are mouth-to-mouth shoving matches—“nature’s version of sumo wrestling," says George Burgess, an ichthyologist at the Florida Museum of Natural History. (See pictures of nine spooky species.)

View Images The sarcastic fringehead is a type of blenny that will fight tooth and nail to protect its eggs and territory. Photograph by Joel Sartore, National Geographic Photo Ark

Watcharapong Hongjamrassilp, of the Scripps Institution of Oceanography in California, adds that the fish also use their needle-sharp teeth in these conflicts. Indeed, a 3-D model of its skull by the University of Washington's Adam Summers shows quite an impressive set of teeth.

As for the wacky name, “fringehead” refers to their cirri—feathery, antenna-like structures on their head that are possibly used to detect chemicals from other fish or movement in the water, all from the safety of their burrows, Hongjamrassilp says.

Burgess says the "sarcastic" part of the name has been attributed to their appearance and quickness to fight, but he says, "I suspect it's the facial expression more than their pugnacious behavior that gives the critter is common name."

Suriname Toad

Females of the South American amphibian go through literally back-breaking labor.

World's Weirdest: Baby Toads Born from Mom's Back Kids getting under your skin? It's no joke for a female Suriname toad—she gives birth to her offspring right out of holes in her back.



Suriname toads develop in eggs embedded in the mom’s back and eventually erupt out of the honeycombed holes, according to Greg Pauly, curator of herpetology at the Natural History Museum of Los Angeles County. (Sufferers of trypophobia, or the fear of holes, may want to steer clear of this critter.)

View Images Suriname toads (pictured, an animal at the St. Louis Zoo) are known for their unusual—but benefical—parental care. Photograph by Joel Sartore, National Geographic Photo Ark

Despite appearances, Pauly says, the Suriname toad is “a great example of parental care in frogs": By carrying babies inside her back, mom keeps them free from predators and parasites. (See "5 Strange Ways Animal Mothers Carry Their Babies.")

Hammerhead Bat

Only the males of this central African species look like bats dressed as moose for Halloween, but there’s a reason for those big schnozzes.

The lads gather in bachelor groups called leks, flapping their wings when the females arrive.

“This song and dance is quite a spectacle,” Mies says. We believe it—the male wingspan can reach more than three feet.

Common Potoo

Native to South America, these nocturnal, brown-feathered birds masterfully masquerade as a tree stump by day.

View Images A common potoo perches on a branch in Peru. The strange birds also have a mournful cry that some perceive as "poor me, all alone." Photograph by All Canada Photos, Alamy

Slits in its eyelids allow the animal to detect movement without opening its giant yellow eyes.

Tiger Moth

This South American insect looks like a famous fast-food clown, but for them it’s all about not ending up as someone's happy meal.

View Images The Idalus herois tiger moth advertises its distastefulness with bright colors. Photograph by Pavel Kirillov, Flickr

The Idalus herois tiger moth produces clicks to jam the natural sonar of bats, which use echolocation to track down prey. Clicking may also advertise a nasty taste, Bill Conner, a biologist at Wake Forest University in North Carolina, says via email.

The sonar jamming and nasty-tasting advertising provide a defense that's “the best of both worlds,” he says.

Plus considering the recent rash of scary clowns popping up around the United States, it's really nice to see one that makes us smile again.

What freaky animals are your favorites? Tell us in the comments below or send us a weird animal question!