One of the changes that goes along with aging is hair color. Red, blonde, black—regardless of the original color, our hair almost always turns gray or silver.

Fish don’t have hair, but many of them do change color as they age. They can take on different color schemes as they move through different stages of life.

Fish change color for many reasons. Some of the changes happen in a flash—a fish might blend into the background to protect itself from predators. Other changes are more gradual. A fish might change color when it switches gender, for example.

Many fish keep the same basic scheme throughout life—especially those that spend their lives in the open ocean. The ones that are more likely to change color as they age are those that move around—they’re born in one place, but they shift habitats as they grow and mature.

Salmon, for example, have stripes when they hatch, in rivers and streams. When they move out to sea, though, they take on a smoother, silvery tone. American eels, on the other hand, are colorless when they hatch, in the open ocean. But as they mature, and move into rivers and streams, they turn dark on top and light-colored on the bottom. And when they return to the ocean to spawn, they turn silvery bronze.

And in some species, only some members change color as they age. Only males of the bluehead wrasse adopt the namesake color, and only when they mark out a territory—a colorful signal that they’re ready to take a mate.

Some of the largest cities in Southeast Asia could be hit by bigger, badder tropical cyclones in the decades ahead. A recent study found that warmer seas and air could change where storms in the region form, how quickly they ramp up, and how long they hang around. The changes could be especially deadly for major cities along the coast.

Researchers used computer models to simulate more than 64,000 cyclones in the region during three eras: 1881 to 1900, 1981 to 2000, and 2081 to 2100. For the future decades, they looked at what conditions would be like under both moderate and extreme warming for the rest of this century. They compared the results for past decades to real storm systems.

The models showed that tropical cyclones—both typhoons and smaller systems—are likely to be born farther north in the western Pacific Ocean, the South China Sea, and the Bay of Bengal, near India. That puts the storms closer to land. The systems are likely to strengthen much more quickly. And they’re likely to last longer after they move ashore. That means higher storm surges, heavier rains, and stronger winds—a deadly combination.

The study said the cities likely to be hardest hit are Bangkok, Thailand; Haiphong, in Vietnam; and Yangon, in Myanmar. Today, their combined population is about 17 million. But they’re expected to grow quite a bit by the end of the century—putting more people at risk from powerful tropical cyclones.

Storms on the Sun can have both beautiful and annoying results. They create widespread displays of auroras—the northern and southern lights. But they can damage satellites, disrupt radio communications, and knock out power grids on the ground. They might even cause some whales to strand themselves.

Solar storms produce huge outbursts of energy and charged particles. Among other things, those outbursts can change the strength and direction of the lines of magnetic force around Earth. Many animals rely on the magnetic field for navigation, including some birds and fish, sea turtles, and lobsters. The list also includes at least two species of whale: gray and sperm whales.

Studies in recent decades have found correlations between the strandings of these whales and solar storms. One study, for example, looked at 400 years of sperm whale strandings in the North Sea. It found much higher stranding rates in years when the Sun was especially “stormy.” A study of 30 years of gray whale strandings found similar peaks—especially when the Sun produced a lot of radio static.

Researchers speculate that the storms could essentially “blind” the whales to the magnetic field. The disoriented whales then could find themselves in shallow waters, and unable to escape.

There’s no confirmation that the storms are causing these strandings. So scientists are studying the subject in greater detail—trying to understand how storms on the Sun can affect life in the oceans.

The female blanket octopus glides through the ocean like a winged phantom. When she’s threatened, she extends some of her arms. That spreads the webbing between the arms, like a flowing cape. The shiny cape makes the octopus look bigger—perhaps scaring away predators.

The octopus is impressive even without the cape. An adult female can be six and a half feet long—the size of a basketball player. Her mate, on the other hand, is about as big as a walnut—perhaps an inch across. And a female may weigh up to 40,000 times as much as a male. That’s the biggest difference in the size of adult males and females in the animal kingdom.

Blanket octopuses are found around the world. They’re in the open ocean and around coral reefs. They’re immune to the sting of a Portuguese man-o’-war, so males and young females sometimes tear off the tentacles and use them to defend themselves against predators.

These octopuses are rarely seen. In fact, the first live male wasn’t discovered until 2001. In part, that’s because of its size—it’s tough to spot something that small in the open ocean. In addition, the male is almost colorless.

A male grows a long arm that it fills with sperm. When he finds a mate, he rips off the arm and hands it to her—then dies. She then stores it in a pouch until she’s ready to fertilize her eggs. She may accept the arms of several suitors. After the eggs hatch, she may die as well—the final act for this phantom of the oceans.

The mangrove tunicate is a mild-looking little creature. It’s a type of sea squirt. It’s only about an inch long, and it feeds by pumping seawater through its body and filtering out the goodies. It’s found in colonies in the roots of mangrove forests around the Gulf of Mexico, the Caribbean, and the Atlantic coast of the United States.

Yet this little critter is a powerful cancer fighter. Researchers have used a compound it produces to create a cancer treatment known as trabectedin. It’s used against several types of cancer—especially those in soft body tissue, such as muscles and fat.

Cancer cells find ways to defeat many types of medication. The cells repair themselves, then continue growing and dividing, forming bigger tumors.

A recent study looked at how trabectedin fights cancer. Researchers discovered that the medication “breaks” the DNA inside cancer cells. Although the cells can fix some types of breaks, these appear to be unfixable—the cancer can’t overcome the disruption. That kills the cancer cells and slows or halts their spread.

Sea squirts are surprisingly close genetic relatives to people. And they’re easy to handle and study, so they’re popular lab subjects. So scientists have used sea squirts to create other medications, including cancer treatments. One produced from a different species is used to fight skin cancer, for example. So these quiet little creatures may yield even more treatment options in the decades ahead.

Marine scientists can’t be everywhere at once. To really understand what’s happening below the waves, though, they need a lot of observations—from many places at many times. So they’re getting help from recreational divers. The divers can carry instruments, or just log what they see.

One project is set to begin in December. Known as BlueDot, it’ll provide insights into how the Mediterranean Sea is warming up—not only at the surface, but down to more than a hundred feet.

Many divers wear small computers on their wrists. The computer records location, depth, temperature, and more. Divers who undergo special training can upload those observations to a central database. Scientists then analyze the results, producing a much better picture of the changing sea.

Another project has been around since 2010—the Great Goliath Grouper Count. Divers at artificial reefs off the coast of Florida log details about the goliath grouper.

It’s one of the largest species of bony fish—up to eight feet long and 800 pounds. But the grouper was overfished, so its population plunged. It’s been protected since 1990, so the numbers have gone up. But the extent of the recovery is still unclear.

Volunteer divers keep an eye out for the grouper during the first half of June. They report where they see the fish, the depth, the size of the fish, and more. That helps biologists determine the goliath grouper population—even if they can’t be everywhere at once.

Hotter oceans are bad for just about everyone. They can destroy coral reefs, cause fish to move to new ranges, and rev up monster hurricanes.

There are problems for octopuses as well. Adults of some species aren’t getting as big as they used to, for example. And a recent study found that the still warmer waters we’ll see in the future could cloud their vision. That would make it harder to catch a meal or get away from predators.

Researchers studied the southern keeled octopus, which is found in shallow waters around Australia. It’s a small octopus that burrows into the sand during the day, then comes out at night to hunt.

The scientists placed females in tanks at three different temperatures: a control temperature of 66 degrees Fahrenheit; the modern summer temperature of 72 degrees; and 77 degrees, which is the projected summer temperature for the end of the century.

Almost all the eggs laid in the two cooler tanks hatched. But two of the three mothers in the warmest tank died while tending their broods, so none of the eggs hatched. The mother of the third brood survived, but less than half of her eggs hatched.

Scientists also studied proteins in the octopus embryos that are important for vision. They keep the lenses clear, and they produce pigments that capture light. The study showed that the warmer the water, the less effective the proteins were. So octopuses that hatch in a hotter ocean might need glasses to find their way.

The ocean floor is turning into a dumping ground. A recent study found that millions of tons of plastic litter the bottom of the world’s oceans and seas. About half of that debris sits in shallow waters near coastlines. And a lot more is expected to settle in the oceans over the coming decades.

The world generates millions of tons of plastic every year—enough to fill a garbage truck every minute. And a lot of it finds its way into the ocean—through runoff, offshore dumping, lost fishing gear, and other sources.

Much of this debris floats on the surface. Some of it forms giant patches, such as the well-known Great Pacific Garbage Patch. Over time, though, a lot of plastic drops into the ocean depths, and much of it settles on the bottom.

To understand how much plastic litters the ocean floor, researchers in Australia poked through the results of many studies. They then developed computer models to analyze those results. Their best model used observations by remotely operated vehicles in the deep ocean.

Their study focused on bits of plastic at least five millimeters across. That accounts for plastic bags, bottles, fishing gear, and other bigger chunks. The model showed that there should be a lot of this debris—somewhere between three million and 12 million tons as of 2020. Almost half of that should be close to shore.

Plastic use is projected to double over the next couple of decades—adding a lot more litter to the ocean floor.

Some strange holes pockmark the bottom of the North Sea. They can be anywhere from a few feet to hundreds of feet wide. But all of them are about four inches deep. That doesn’t match the kinds of pits produced by geological processes or ocean currents. Instead, a recent study says they were created on porpoise.

Scientists have known about the pits for years. The most common explanation said they were produced by blobs of methane bubbling up through the sediments. But such pits are cone shaped. And wider methane pits are also deeper.

To learn more about these odd depressions, researchers studied the floor of the North Sea off the coast of Germany. Using sophisticated sonar, they mapped the sea floor in great detail. They saw more than 40,000 of the pits. And they found that, over a six-month-period, the pits changed. Some of them got bigger, others merged, and new ones took shape.

The scientists also studied ocean currents and marine life in the region. And they found that it’s part of the habitat of the harbor porpoise.

The team suggested that the porpoises scour the shallow pits while they’re hunting for sand eels, which can burrow a few inches into the sediments. The porpoises are known to use their snouts to dig into the soft sand and mud. That poking around may scare the critters out of their hiding places, making them easy prey. And stirring up one sand eel might make others try to get away as well—escaping from pits dug by hungry porpoises.

If you live near the coast, few words are scarier than these: Category Five. That’s the classification for the most powerful hurricanes. The storms have maximum sustained winds of at least 157 miles per hour. And their potential damage is catastrophic. They can flatten houses, bring massive storm surges, and cause heavy rainfall well inland.

In recent years, the most powerful tropical storms have been getting even stronger. And as our planet continues to warm up, they’re expected to get stronger still. So some scientists think it’s time to add even scarier words to the tropical-storm lexicon: Category Six. To qualify for this category, a storm would have wind speeds of at least 192 miles per hour.

A recent study found that five storms would have reached that threshold in the past nine years—four typhoons in the western Pacific Ocean, and one hurricane in the eastern Pacific—Hurricane Patricia. It hit the Pacific coast of Mexico with peak sustained winds of 215 miles per hour—the strongest storm yet recorded.

The study also projected that such monster storms will become more common in the years ahead. Climate change is making the oceans warmer, providing extra “fuel” to power typhoons and hurricanes. That may not increase the number of tropical storms, but it is expected to make the strongest of them even more intense. Some would even qualify for Category Six—a scarier name for the most powerful storms.