Baby Eels Migrate by Following Magnetic Fields

Alessandro Cresci
Alessandro Cresci

Baby eels have joined the ever-growing club of animals that live their lives along magnetic lines. Researchers described these findings in the journal Scientific Advances.

Our planet and its inhabitants are shaped and impelled by invisible forces. Studies have found that foxes hunt and deer flee along north-south lines. Pigs and wild boars orient their nests to face the same way. Lobsters, butterflies, and whales all follow their internal compasses along magnetic lines. Adult European eels, too. But we weren’t really sure about their babies.

Grown-up European eels lay their many eggs in the Sargasso Sea. The eggs hatch into helpless larvae, which bob along in Atlantic currents. As the currents approach the continent, the babies transform again, this time into translucent miniature versions of their parents. These glass eels make their way into the coasts. From there, they swim inland to freshwater and bum around Europe and North Africa for five to 20 years. Finally, as adults, they head back to the sea to start the whole cycle all over again. It's one of the longest migrations in the animal kingdom, the researchers say.

Adult European eel traveling over icy ground on its migration route
Adult European eels are tough and can migrate short distances over land.
Caroline Durif

It’s an impressive feat for the little noodles, and scientists wondered how they pull it off. To find out, researchers scooped up a group of newly arrived baby eels on the coast of Norway. They put the eels in a large chamber inside a fjord and let them swim there for a full tidal phase, watching how the eels positioned their bodies and how they swam.

Next, they brought the eels into the lab and repeated the tide-long observation process.

Unsurprisingly, the little tykes knew exactly what they were doing. They consistently turned their bodies to run parallel with magnetic lines, but the direction of those lines varied depending on the phase of the tides. When the tide went out to sea, the majority of eels swam southward, whether in the fjord or in the lab.

These findings are as fascinating as they are vital, as, for all its ingenuity, the European eel is critically endangered. Understanding this animal’s extraordinary life cycle could help conservationists find ways to protect it better in the future.

7 Top-Rated Portable Air Conditioners You Can Buy Right Now

Black + Decker/Amazon
Black + Decker/Amazon

The warmest months of the year are just around the corner (in the Northern Hemisphere, anyway), and things are about to get hot. To make indoor life feel a little more bearable, we’ve rounded up a list of some of the top-rated portable air conditioners you can buy online right now.

1. SereneLife 3-in-1 Portable Air Conditioner; $290

SereneLife air conditioner on Amazon.
SereneLife/Amazon

This device—currently the best-selling portable air conditioner on Amazon—is multifunctional, cooling the air while also working as a dehumidifier. Reviewers on Amazon praised this model for how easy it is to set up, but cautioned that it's not meant for large spaces. According to the manufacturer, it's designed to cool down rooms up to 225 square feet, and the most positive reviews came from people using it in their bedroom.

Buy it: Amazon

2. Black + Decker 14,000 BTU Portable Air Conditioner and Heater; $417

Black + Decker portable air conditioner
Black+Decker/Amazon

Black + Decker estimates that this combination portable air conditioner and heater can accommodate rooms up to 350 square feet, and it even comes with a convenient timer so you never have to worry about forgetting to turn it off before you leave the house. The setup is easy—the attached exhaust hose fits into most standard windows, and everything you need for installation is included. This model sits around four stars on Amazon, and it was also picked by Wirecutter as one of the best values on the market.

Buy it: Amazon

3. Mikikin Portable Air Conditioner Fan; $45

Desk air conditioner on Amazon
Mikikin/Amazon

This miniature portable conditioner, which is Amazon's top-selling new portable air conditioner release, is perfect to put on a desk or end table as you work or watch TV during those sweltering dog days. It's currently at a four-star rating on Amazon, and reviewers recommend filling the water tank with a combination of cool water and ice cubes for the best experience.

Buy it: Amazon

4. Juscool Portable Air Conditioner Fan; $56

Juscool portable air conditioner.
Juscool/Amazon

This tiny air conditioner fan, which touts a 4.6-star rating, is unique because it plugs in with a USB cable, so you can hook it up to a laptop or a wall outlet converter to try out any of its three fan speeds. This won't chill a living room, but it does fit on a nightstand or desk to help cool you down in stuffy rooms or makeshift home offices that weren't designed with summer in mind.

Buy it: Amazon

5. SHINCO 8000 BTU Portable Air Conditioner; $320

Shinco portable air conditioner
SHINCO/Amazon

This four-star-rated portable air conditioner is meant for rooms of up to 200 square feet, so think of it for a home office or bedroom. It has two fan speeds, and the included air filter can be rinsed out quickly underneath a faucet. There's also a remote control that lets you adjust the temperature from across the room. This is another one where you'll need a window nearby, but the installation kit and instructions are all included so you won't have to sweat too much over setting it up.

Buy it: Amazon

6. Honeywell MN Series Portable Air Conditioner and Dehumidifier; $400

Honeywell air conditioner on Walmart.
Honeywell/Walmart

Like the other units on this list, Honeywell's portable air conditioner also acts as a dehumidifier or a standard fan when you just want some air to circulate. You can cool a 350-square-foot room with this four-star model, and there are four wheels at the bottom that make moving it from place to place even easier. This one is available on Amazon, too, but Walmart has the lowest price right now.

Buy it: Walmart

7. LG 14,000 BTU Portable Air Conditioner; $699

LG Portable Air Conditioner.
LG/Home Depot

This one won't come cheap, but it packs the acclaim to back it up. It topped Wirecutter's list of best portable air conditioners and currently has a 4.5-star rating on Home Depot's website, with many of the reviews praising how quiet it is while it's running. It's one of the only models you'll find compatible with Alexa and Google Assistant, and it can cool rooms up to 500 square feet. There's also the built-in timer, so you can program it to go on and off whenever you want.

Buy it: Home Depot

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

Fiona the Hippo Is Now on Cameo

Mark Dumont, Flickr // CC BY-NC 2.0
Mark Dumont, Flickr // CC BY-NC 2.0

Fiona the Hippo has earned her status as a celebrity. Born prematurely and weighing just 29 pounds in 2017, she became a sensation when she beat the odds and survived. Now, the Cincinnati Zoo's most beloved resident is taking her famous mug to Cameo.

Cameo is a service that allows fans to pay for personalized video messages from various celebrities. Most celebrities on the website are people, but that hasn't stopped Fiona from offering her star presence to the public.

For $100, you can request a custom video from the Cincinnati Zoo starring Fiona. A zoo staff member will recite the message while filming Fiona being adorable in her enclosure. One example video shows Fiona hanging out with her mom and snacking on some lettuce while her caretaker wishes the recipient a happy birthday.

Animal lovers who pay for a Cameo from Fiona will be supporting a good cause, too. Proceeds from the purchase will go to the Cincinnati Zoo, which is currently operating at limited capacity due to the COVID-19 pandemic. If you have a Cameo account, you can request your own video message for $100 here.

This isn't the first time the Cincinnati Zoo has used Fiona's popularity as a fundraising tool. Earlier this year, the zoo started selling the dung left behind by Fiona and other animals as garden fertilizer.