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.

Looking to Downsize? You Can Buy a 5-Room DIY Cabin on Amazon for Less Than $33,000

Five rooms of one's own.
Five rooms of one's own.
Allwood/Amazon

If you’ve already mastered DIY houses for birds and dogs, maybe it’s time you built one for yourself.

As Simplemost reports, there are a number of house kits that you can order on Amazon, and the Allwood Avalon Cabin Kit is one of the quaintest—and, at $32,990, most affordable—options. The 540-square-foot structure has enough space for a kitchen, a bathroom, a bedroom, and a sitting room—and there’s an additional 218-square-foot loft with the potential to be the coziest reading nook of all time.

You can opt for three larger rooms if you're willing to skip the kitchen and bathroom.Allwood/Amazon

The construction process might not be a great idea for someone who’s never picked up a hammer, but you don’t need an architectural degree to tackle it. Step-by-step instructions and all materials are included, so it’s a little like a high-level IKEA project. According to the Amazon listing, it takes two adults about a week to complete. Since the Nordic wood walls are reinforced with steel rods, the house can withstand winds up to 120 mph, and you can pay an extra $1000 to upgrade from double-glass windows and doors to triple-glass for added fortification.

Sadly, the cool ceiling lamp is not included.Allwood/Amazon

Though everything you need for the shell of the house comes in the kit, you will need to purchase whatever goes inside it: toilet, shower, sink, stove, insulation, and all other furnishings. You can also customize the blueprint to fit your own plans for the space; maybe, for example, you’re going to use the house as a small event venue, and you’d rather have two or three large, airy rooms and no kitchen or bedroom.

Intrigued? Find out more here.

[h/t Simplemost]

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

Who Was Jim Crow?

Wikimedia Commons, Public Domain
Wikimedia Commons, Public Domain

The name Jim Crow appears throughout many U.S. history books. It's used in reference to both the laws that segregated Black and white Americans in the Southern United States and the region itself during the period when these laws were enforced. Jim Crow Laws and the Jim Crow South were very real from the late 19th through the mid-20th centuries, but a real person named Jim Crow never existed. The name comes from a fictional character used to perpetuate racist stereotypes before the Civil War.

According to Ferris State University, a white performer named Thomas Dartmouth Rice originated the Jim Crow caricature in the 1830s. Rice, known as "the Father of Minstrelsy," would don blackface and affect an exaggerated African American dialect while performing his musical act. Jim Crow was meant to be a racist stereotype of an enslaved person: Like many minstrel personas that came after him, the character was portrayed as a clumsy buffoon.

Though Rice didn't invent minstrelsy, his success helped popularize the stage show format. Inspired by Rice, other minstrel actors borrowed his Jim Crow routine, and soon whites were using the name as a derogatory term for African Americans.

Even after slavery was abolished and minstrel shows faded into obscurity, the Jim Crow character lived on as a label. According to History, the first Jim Crow laws were passed in the Reconstruction Period as a way to limit the rights and resources of newly freed Blacks in the South. Such laws imposed literacy tests on Black voters, segregated public schools, and made it legal for businesses to segregate their customers by race.

How exactly these laws became associated with Jim Crow is unclear, but the phrase Jim Crow Laws was being used by the late 19th century. An 1892 article from The New York Times used the wording when reporting on Louisiana's segregated railroad cars.

Though most people may not be aware of the name's origins, Jim Crow still comes up today when discussing this dark period in U.S. history and its lasting effect on the country.

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