What Causes Red Tides?

William West/AFP/Getty Images
William West/AFP/Getty Images

Every once in a while, the ocean turns the color of blood and scores of dead fish rise to the surface. The phenomenon might look like a biblical plague, but the source is far more mundane. It's just algae.

Red tides occur when there’s a sudden population boom among specific kinds of algae, which in enormous quantities become visible to the naked eye. They occur all over the world. In the Gulf of Mexico, the culprit behind red tides washing onto coastlines from Texas to Florida is usually a type of microscopic algae called Karenia brevis. It produces toxic chemicals that can cause symptoms ranging from sneezing and eye irritation to disorientation, vomiting, and breathing difficulties. It's often fatal for fish, shellfish, turtles, and other wildlife.

The water appears red because of the particular depth at which the algae live. Light waves don’t penetrate seawater evenly, and certain wavelengths travel farther than others. The algae that cause red tides grow at depths that absorb green and blue frequencies of light and reflect red ones.

Not all algal blooms are red; some are blue, green, brown, or even purple. Nor do all algae harm humans or animals. Why and how certain species of algae multiply like crazy and wipe out entire swaths of marine life is still a scientific mystery.

The worst red tide on record occurred in 1946, when a mass of algae stretching for 150 miles along the Florida coastline killed more than 50 million fish, along with hundreds of dolphins and sea turtles. Tourists shied away from the beaches as the bodies of dead sea creatures washed ashore. Smaller incidents are more common, but just as costly. In the past decade alone, fishing and tourism industries in the United States have had an estimated $1 billion in losses due to red tides—and the cost is expected to rise.

Editor's note: This story, which originally ran in 2015, was updated in August 2018.

Amazon's Best Cyber Monday Deals on Tablets, Wireless Headphones, Kitchen Appliances, and More

Amazon
Amazon

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

Cyber Monday has arrived, and with it comes some amazing deals. This sale is the one to watch if you are looking to get low prices on the latest Echo Dot, Fire Tablet, video games, Instant Pots, or 4K TVs. Even if you already took advantage of sales during Black Friday or Small Business Saturday, Cyber Monday still has plenty to offer, especially on Amazon. We've compiled some the best deals out there on tech, computers, and kitchen appliances so you don't have to waste your time browsing.

Computers and tablets

Amazon

- Amazon Fire HD 10 Tablet 64GB; $120 (save $70)

- Amazon Fire HD 8 Tablet 64GB; $84 (save $35)

- HP Pavilion x360 14 Convertible 2-in-1 Laptop; $646 (save $114)

- HP Pavilion Desktop, 10th Gen Intel Core i3-10100 Processor; $469 (save $81)

- Acer Nitro 5 Gaming Laptop; $973 (save $177)

Headphones and speakers

Beats/Amazon

- Bose QuietComfort 35 II Wireless Bluetooth Headphones; $200 (save $100)

- Sony Bluetooth Noise-Canceling Wireless Headphones; $278 (save $72)

- JBL LIVE Wireless Headphones; $100 (save $30)

- JBL Charge 4 - Waterproof Portable Bluetooth Speaker; $120 (save $10)

- Bose SoundLink Color Bluetooth Speaker II; $79 (save $50)

- Powerbeats Pro Wireless Earphones; $200 (save $50)

Video Games

Sony

- Watch Dogs Legion; $30 (save $30)

- Marvel's Avengers; $27 (save $33)

- Ghost of Tsushima; $40 (save $20)

- The Last of Us Part II; $30 (save $30)

TECH, GADGETS, AND TVS

Samsung/Amazon

- Amazon Fire TV Stick; $30 (save $20)

- Echo Show 8; $65 (save $65)

- Nixplay Digital Picture Frame; $115 (save $65)

- eufy Smart Doorbell; $90 (save $30)

- Samsung 75-Inch Class Crystal 4K Smart TV; $898 (save $300)

home and Kitchen

Ninja/Amazon

- T-fal 17-Piece Cookware Set; $124 (save $56)

- Le Creuset Enameled Cast Iron Curved Round Chef's Oven; $180 (save $136)

- Ninja Foodi 10-in-1 Convection Toaster Oven; $195 (save $105)

- Roborock E4 Robot Vacuum Cleaner; $189 (save $111)

- Instant Pot Max Pressure Cooker 9 in 1; $80 (save $120)

- Shark IZ362H Cordless Anti-Allergen Lightweight Stick Vacuum; $170 (save $110)

Sign Up Today: Get exclusive deals, product news, reviews, and more with the Mental Floss Smart Shopping newsletter!

Why Do Cats Throw Up So Often?

Pixabay, Pexels
Pixabay, Pexels

Nearly every cat owner is used to regularly finding something their kitty coughed up hidden around their home. Vomiting in cats can happen so often that it's easy to grow desensitized to the behavior, but veterinarians say that the sight of your cat throwing up should never be ignored. Though it's usually benign, vomiting may indicate a health problem that needs to be taken care of.

To gauge whether your cat's puke is a sign of something serious, look for certain clues. According to The Spruce Pets, eating too fast is one of the most common causes of vomiting in cats, and it's usually harmless. If your cat hacks up undigested food immediately following meal times, that's likely the culprit. This behavior can be prevented by feeding your pet smaller portions, or adding an obstruction like a medium-sized ball to their bowl that they have to eat around. If the problem still persists, there may be something else causing it.

Hairballs are another potential source of your cat's retching. They may be just a gross annoyance to you, but to your cat, they can pose a serious health risk. Cats cough up the fur they can't digest, and if they don't, it could create a dangerous obstruction in their bowels. One way to help your hairball-prone cat is to brush them regularly. That way, there will be less fur for them to lick up.

These are the less concerning reasons for a cat to throw up. Vomiting can also be a symptom of health problems like feline inflammatory bowel disease, feline diabetes, hyperthyroidism, and chronic kidney disease. It's also possible that your cat ingested something harmful.

If there's no obvious explanation for your cat's vomiting, it's a good idea to reach out to your vet. While throwing up one to three times a month is considered normal, a cat that throws up multiple times in a short period may need medical attention. When analyzing your pet's behavior, look for other symptoms as well: Cats that exhibit symptoms like diarrhea or loss of appetite in addition to throwing up should always be taken to the vet.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.