A strange phenomenon is unfolding in Fairbanks, Alaska, where several foot-long Arctic lampreys have reportedly "fallen from the sky". But while these odd-looking fish have inspired their own Sharknado-esque horror movie, the explanation here is actually quite tame. 

Arctic lampreys have fewer teeth than their invasive cousins, the sea lampreys. Image: Alaska Department of Fish and Game

Also known as cyclostomes (meaning "round mouths"), lampreys are some of the most primitive vertebrates alive today. They don't have jaws, but instead boast a round, sucker-like mouth covered in an array of keratin "teeth" (the same protein that makes up your hair and fingernails). It's no surprise that Alaskan locals were a bit unnerved by their newly airborne visitors, but Lamprey Conservation Management assures us that there's a perfectly reasonable explanation: hungry birds are to blame. 

"We recently observed a similar situation in Limerick City, Ireland," they explain. "A little boy was waiting for his mother in the car when this adult lamprey fell out of the sky and landed on the window. The fish was still alive and attached to the car when she returned."

"Hey, kid! Let me in!" Image: Lamprey Conservation and Management 

The events time perfectly with lamprey spawning season, which typically occurs from May to July. "We think the Fairbanks fish are being pulled out of the Chena River [by birds], where lampreys come to lay their eggs," says the Alaska Department of Fish and Game (ADFG). "Their odd mouths and eel-like body shape makes them hard to catch. The gulls are likely dropping the squirming critters while in flight." 

Like salmon, most lampreys are anadromous, meaning they spend most of their lives at sea, but return to fresh water to spawn. Upon reaching a suitable breeding area, a male will wriggle around to create a depression on the riverbed. Lamprey lovin' isn't exactly gentle: the male attaches to the back of the female's head with his teeth (so kind) and wraps around her body while she deposits some 25,000 eggs.

As adults, lampreys mostly feed on flesh and bodily fluids by attaching to small fishes and rasping away. But since juveniles lack the necessary mouth gear, they must spend an astounding three to seven years in the muddy waters they're born in, filtering organic particles from the water while their teeth grow.

We anticipate it will remain "cloudy with a chance of lamprey" in Fairbanks over the coming months, but this actually presents an exciting opportunity for scientists. Unlike invasive sea lampreys (pictured in the header above), which have become something of an ecological pest in other states, Arctic lampreys are native to Alaska. "We actually like them up here," laughs ADFG educator Erik Anderson. "[The lamprey population] is just another thing that makes Alaska an amazing place, and there is still a lot to learn about it."

Image: Alaska Department of Fish and Game
Image: Alaska Department of Fish and Game
Closer inspection shows marks left by hungry birds. Image: Alaska Department of Fish and Game

UPDATE (June 19, 08:00 PST) This crazy story inspired an amazing "doodle" from one of our favourite artists, Perrin Ireland!

Image: Perrin Ireland

Top header image: US Fish and Wildlife Pacific Region/Flickr