10 Weird Creatures From the Mariana Trench

Frilled Shark
Because of its long body, the frilled shark sometimes looks like an eel at first glance. © 2015 HowStuffWorks, a division of Infospace LLC

Frilled sharks look like a mix-and-match special from the discount aisle at your local evolution convenience store. They have the rounded body of an eel paired with a flattened head that would like right at home atop a terrestrial dinosaur. Perhaps that's fitting, because like many sharks, this species has ancient roots that extend back nearly 80 million years.

The shark derives its name from six rows of frilly gills that grace its body, which grows up to 6 feet (1.8 meters) long. Just as notably, the shark wields more than 20 rows of wicked, trident-shaped teeth that will tear into any bit of flesh that passes near them.

Frilled sharks probably spend most of their lives near the ocean's bottom, and they like waters more than 4,000 feet (1,219 meters) deep. On the rare occasions that people snag them and bring them to the surface, the sharks almost always perish immediately, making it very difficult for us to observe their behavior and lifecycles.

For years, many people assumed that frilled sharks swam and hunted like eels. Some researchers think an awkward arrangement of internal organs would make that kind of movement impossible. Instead, they say, these sharks may actually strike their prey with the action of a land-based snake, making them even weirder.