Science and the Sea podcast

When tropical storm systems barrel across the Atlantic Ocean toward North America, they often take aim at the Lesser Antilles—an arc of small islands that marks the eastern boundary of the Caribbean Sea. In fact, the islands often are the first thing forecasters talk about when a tropical system heads our way.The Lesser Antilles arc from the U.S. Virgin Islands, near Puerto Rico, all the way down to South America. They comprise three separate groups: the Leeward Islands, the Windward Islands, and the Leeward Antilles. The Windwards extend farthest into the Atlantic. They were the first stop for European sailing ships, which followed the prevailing winds to the Americas.Most of the islands are volcanic. They formed as two of the plates that make up Earth's crust plunged below the Caribbean Plate. As the rock descended, it melted. Some of the molten rock then forced its way upward, building the islands.Earthquakes rock some of the islands. And some of the volcanoes that built the islands are still active. A massive eruption that began in 1995, for example, destroyed the capital of the island of Montserrat, and forced most of the population to leave the island.Despite the volcanoes and hurricanes, many of the individual islands are popular tourist sites. Places like the Virgin Islands, Aruba, and Martinique offer tropical beaches, coral reefs, rugged mountains, and other natural attractions—at the edge of the Caribbean Sea.

For some coral, home isn't where the heart is—it's where the sounds are. A recent study showed that one type of coral prefers to settle on reefs that sound healthy—even if they're not.Young corals, known as larvae, float or swim through the water for a while. When they find a good spot, they drop to the bottom and grab hold. They use several cues to find the best locations, including the lighting and chemistry. And according to the study, one of those cues might be sounds.Biologists recorded the sounds of both healthy and un-healthy reefs in the U.S. Virgin Islands. Healthy reefs are noisy. They feature the clicks of snapping shrimp and the grunts and groans of fish. Unhealthy reefs are much quieter.The scientists placed small groups of larvae in special containers on three reefs. One reef was healthy, with a good amount of coral. The others had less coral and much more algae, which can kill a reef.Researchers played the sounds of a healthy reef to the larvae on one of the damaged reefs. On the other two reefs, the larvae had only the natural sound of the environment.On average, the larvae that were played the healthy sounds were 1.7 times more likely to settle on the reef than those at the other reefs—even the healthy one. So playing a nice lullaby into damaged reefs might lure new generations of coral in the years ahead.Our thanks to T. Aran Mooney of the Woods Hole Oceanographic Institution for the reef sounds.

The oceans are losing their memory. That could make it harder to forecast everything from monsoons to blizzards.Ocean “memory” is maintained in the top layer, called the mixed layer. Winds push warm surface water downward, where it mixes with water at greater depths. This layer is typically about 150 feet thick. And overall, it maintains a fairly constant temperature. When the temperature changes as the result of some major event, it can take 10 to 20 years for the change to dissipate. In other words, the ocean maintains the “memory” of what happened to it for that long.As the air warms up, though, ocean memory may be changing. Researchers recently simulated changing ocean conditions with computer models. Their work suggested the memory span may be getting shorter, mainly because water at the surface is getting warmer and less dense, so it doesn't sink as easily. As a result, the mixed layer gets thinner, so its temperature can change more quickly. The quicker the change, the shorter the memory. As one researcher described it, the ocean develops amnesia.Ocean memory is an important factor in forecasting conditions in both the oceans and the atmosphere. Scientists use it to predict monsoon seasons, heatwaves, exceptionally wet summers and cold winters, and other major climate events. A shorter ocean memory could cut months from the lead time of these forecasts—making it harder to remember whether to take an umbrella or sunscreen on your next outing.

Otto the octopus didn't appreciate the spotlight shining on his laboratory tank at night. So he turned it off. In fact, he turned off the lights in the whole lab.Octopuses are smart and curious. They use tools and learn from watching other octopuses. They can solve mazes, open the lids of glass jars, and build dens.In the lab, they learn to tell people apart. They've been known to take a disliking to some of the lab workers, squirting jets of water at them when they walk by. And they can show a clear preference for the people who feed them.Octopuses also play. In one study, scientists put some small, sealed plastic bottles in octopus tanks. Some of the critters fired jets of water at the bottles, bouncing them off the walls. Others fired a bottle toward the tank's inlet valve, so the bottle came back to them—like octopus ping-pong.And that brings us back to Otto. Scientists in Germany were studying the behavior of Otto and several others. Otto was the most active. He damaged the glass walls of his tank by throwing rocks at them, and he sometimes rearranged the stuff in the tank.A 2,000-watt spotlight shined on the tank at night. But several times, the light shorted out—and so did the rest of the lab. Scientists then spent the night in the lab to figure out what was happening. Otto was climbing to the rim of the tank and squirting water at the light. That turned out the lights—perhaps allowing Otto to get a good night's sleep.

A rare species of sponge found in the Red Sea and Indian Ocean has a rare distinction: It has levels of a metal that are thousands of times higher than ever seen in any other organism. And most of that metal is stored away by a type of bacteria that lives inside the sponge.Sponges are filter feeders—they draw in water, filter out food and other solid bits, then shoot the water and solid particles back into the sea. Some contaminants can lodge inside them. Some studies have found high levels of arsenic, barium, and other toxic substances.A more recent study looked at the species called Theonella conica. It's found down the eastern coast of Africa. Up to 40 percent of its body weight consists of bacteria and other microscopic organisms, many of which have a symbiotic relationship with the sponge.Over two decades, researchers collected specimens from Zanzibar, off the southeastern African coast, and the Gulf of Aqaba, at the northern tip of the Red Sea.When they analyzed the sponges, the scientists found extremely high levels of molybdenum. The metal is important for the metabolism of people and other animals, but only at low levels. At high levels it's toxic. So the metal may help protect the sponges from predators.The element was concentrated in one of the species of bacteria inside the sponge. It changes the material into a harmless mineral, which is flushed back into the water—keeping the sponge safe from both predators and the toxic element.

The journey around Cape Horn, at the southern tip of South America, is one of the most treacherous in the world. The cape has claimed hundreds of ships and thousands of sailors. Not many commercial vessels make the journey today. But for sail-powered yachts, rounding the cape is a big attraction—like climbing Mount Everest.Cape Horn is named for the home town of the Dutch navigator who described it, in 1616. It's a small island that features a cliff a quarter of a mile high.The cape is where the Atlantic and Pacific oceans meet. The confluence generates strong currents. Those currents are magnified by the contours of the ocean floor, which features many sunken islands.The region is in the “Furious Fifties”—latitudes of more than 50 degrees south. Strong winds blow from west to east. Those are funneled by the mountains of South America and Antarctica. That creates a wind tunnel effect, so winds almost always blow at gale force. And they frequently top hurricane force, battering any ships that challenge the passage.In addition, icebergs are common features, and storms bring heavy rain, hail, sleet, and snow. That all combines to make a journey around Cape Horn especially challenging.The opening of the Panama Canal, in 1914, provided a safe shortcut between the east and west coasts of the Americas. But big tankers, naval vessels, cruise ships, and private yachts still round the cape—one of the most dangerous ocean voyages in the world.

The coconut crab is the 800-pound gorilla of many tropical beaches. Not only is it the biggest and strongest crab on land, it'll eat just about anything—animal, vegetable, or even mineral.Coconut crabs are found in tropical environments in the Indian and southwestern Pacific oceans. They hatch in the sea, where they float around for a few weeks. They then move ashore, where they live in the discarded shells of other creatures. The crabs lose the shells when they become adults. They stay close to the beach, but they don't go back in the water; they have lungs instead of gills, so they drown if they stay underwater for long.An adult coconut crab has a leg span of about three feet, and can weigh up to nine pounds. It has powerful claws that can crack open a coconut and scoop out the meat. It can even climb a tree to knock a coconut to the ground.The crabs also have been seen to climb trees to attack seabirds. Most of their diet consists of fruits, seeds, and dead animals. They eat abandoned shells for their calcium. But they sometimes grab birds, rats, or even other crabs. And they steal many human artifacts, from pots and pans to firearms, so they're also known as robber crabs.Coconut crabs have been wiped out in some regions. They're hunted for their meat, crowded out by human development, and damaged by higher sea level and warmer oceans. Some areas offer legal protection—a helping hand—or claw—for these giants of the beach.

It looks like something a six-year-old dreamed up in art class—the body of a fish, the “wings” of a bird, the legs of a crab, and even the taste buds of a human tongue. Throw in some loud croaks and grunts, and you've got one of the ocean's many oddities: the sea robin.The fish is found in warm waters around the globe—usually in shallow water with a sandy or rocky bottom. A typical adult is a foot or more long, although some species can reach twice that size. The fish have tapered bodies, and heavy skulls that help them poke around the bottom for food—shrimp, clams, crabs, and small fish.When a sea robin swims, the fins on the sides of its body fan out like the wings of a bird—hence the name. As the fish matures, the “rays” at the front of these fins change. They form small “legs” that the fish uses to walk along the bottom.But the legs are for more than just getting around. The fish uses them to feel out prey. And at least one species may use them to “taste” prey before they ever see it.In a recent lab study, biologists buried some of the sea robin's favorite foods below the sand and watched them feel it out. They then buried some of the chemicals produced by the prey. And they found that one species quickly dug up those goodies as well. The legs of those fish were coated with tiny sensory organs that are a bit like the taste buds on your tongue. They allow the sea robin to “taste” its food well before it even swallows it.

A steep change in the slope of a riverbed can create rapids—regions where the water is especially fast and choppy—and dangerous. The same thing applies to rivers in the sky. Steep changes in altitude, temperature, or pressure can concentrate the water, creating rapids. They can cause downpours that are especially fast and heavy—and dangerous. That appears to be the case for recent springtime flooding in the Middle East.Atmospheric rivers form when water evaporates from the ocean. As it rises, it's caught in a jet stream, forming a tight, high-speed river. The average one delivers as much water per minute as the mouth of the Mississippi River.When an atmospheric river crosses land, it can produce rain and snow. That can be helpful. But it also can be deadly, producing flooding, mudslides, and other dangers.A recent study blamed deadly flooding in the Middle East in April 2023 on such a river, but one with rapids—waves with much higher concentrations of water. They dumped as much rain as some regions see in an entire year. Similar flooding in 2024 also might have been caused by rapids. The rapids were powered by evaporation from the Atlantic Ocean and the Arabian and Mediterranean seas.Our warming climate is increasing the rate of evaporation. It's also changing circulation patterns over the Atlantic. So the deserts of the Middle East could see more flooding in the years ahead—perhaps powered by rivers and rapids high in the sky.

The great white shark has the most fearsome reputation of all sharks. But it might not be the biggest of the predator sharks. That honor might go to the Pacific sleeper shark. The biggest one ever seen appeared to be about 23 feet long—longer than the biggest great white.The Pacific sleeper is found mainly in cold waters around the rim of the northern Pacific Ocean. But some have been seen in warmer waters close to the equator.The shark got its name because it was thought to spend most of its time near the bottom, waiting for prey to swim by—a “sleepy” sort of behavior. But at least one study found otherwise. The sharks were found to move up and down through the water column, from the bottom to near the surface. And some covered as much as three or four miles a day.Pacific sleepers will eat just about anything. They prefer fish that dwell on the bottom, along with giant octopus. But their stomach contents also show other types of fish, snails, sea lions, and other prey. They might have hunted down some of them, and gobbled the already dead remains of others.The shark hasn't been studied that much. The largest one ever caught was about 14 feet long and weighed half a ton. But video cameras caught one that was estimated at 23 feet.Pacific sleepers probably grow slowly and have a low reproduction rate. So they could be threatened by overfishing, mostly as bycatch—draining the population of what might be the largest of all predator sharks.

Currents at the bottom of the ocean can be just as fickle as wind currents at the surface. They can turn, speed up or slow down, and even reverse course. And they can change in just days or even hours.That's the conclusion of the most detailed study of sea-floor currents to date. Researchers anchored 34 instrument packages across a thousand-square-mile region off the coast of Mozambique, at the southeastern corner of Africa. The instruments monitored the currents for four years.The study took place on the continental slope, at depths of up to a mile and a half. The slope is steep, and sharp canyons notch into it. Sediments tumble down the slope and through the canyons.At the bottom of the slope, the currents generally flow from south to north. And in the canyons, they generally flow downhill. Speeds range from about a half to one-and-a-half miles per hour.But researchers found a lot of variation. The speed changes, and so does the direction. Currents can even reverse direction—even in the canyons, where they sometimes flow uphill. Some of the changes are related to the tides or to passing storms or eddies. And others are related to the seasons, so they play out over days or weeks.The researchers say a better understanding of sea-floor currents can tell them more about where ocean sediments come from. That can help them better understand changes in climate, the sources of pollution, and more—swirling along at the bottom of the sea.

In the spring of 1956, a doctor in the Japanese village of Minamata reported an outbreak of a troubling new disease. It was seen mainly among children, and it affected the central nervous system. The disease quickly spread, with hundreds of cases reported, then thousands. It took years for scientists to work out the cause: poisoning from industrial pollution in Minamata Bay—the first known case of a disease caused by polluted seawater.A chemical factory was pumping huge amounts of wastewater into the bay. The water was laced with mercury. Some of it was methylmercury—an especially nasty form.Microscopic organisms gobbled the stuff up, then were eaten by larger organisms. The amount of mercury built up to higher and higher levels with each link in the food chain. So the fish and shellfish eaten by people were filled with it. That triggered Minamata disease. Symptoms included numbness, problems with vision and hearing, trouble walking, and tremors. The disease killed hundreds, and may have afflicted millions. And its effects are still being felt.The company dredged the bay to remove contaminated sediments. And the nations of the world crafted a treaty to reduce the amount of methylmercury in the environment. It calls for less mercury in products and manufacturing, fewer emissions of it from coal-fired power plants, and better storage and disposal.Even so, mercury and other chemicals still cause problems as they work their way up the marine food chain.

The parrotfish is like a house cleaner who does a great job of keeping things tidy, but sometimes breaks a glass. You want to keep them around, but you just wish they'd be a little less destructive.For the parrotfish, the “houses” are coral reefs. They clean tiny organisms off the coral, keeping the coral healthy. But they also chip off pieces of the coral. If they chip away too much, they can damage the coral.Parrotfish have strong teeth. They grind up the coral they chip off, then poop it out as grains that can wash up on the beach as white sand.The scraping can scar the hard coral—the “skeleton” created by the living organisms inside, known as polyps. In many cases, the coral heals as new polyps move in. But in others, the coral can collapse. And if too many corals are destroyed, an entire reef can suffer.Researchers spent a decade studying the coral-parrotfish relationship in four regions of the Caribbean Sea. They looked at individual corals, complete reefs, and wider areas that encompass many reefs. They also studied the parrotfish populations.They found that more parrotfish generally meant more damage to the corals—but not always. Parrotfish prefer some species of corals over others. So in regions where those species weren't as common—or where there was less variety of coral species—the damage was less severe.The results may help managers control the parrotfish catch—perhaps improving the health of coral reefs across the Caribbean.

The exhaust produced by ocean-going ships can contribute to our warming climate. Most ships burn fossil fuels, so they spew out atmosphere-warming compounds. But some of their contribution to global warming may be a result of lower emissions—not of carbon, but of sulfur.One of the compounds produced by burning fossil fuels is sulfur dioxide. Sunlight can cause it to interact with other compounds. That can yield droplets of acid rain, plus tiny grains of sulfur. Water can condense around those grains, forming clouds. The sulfur can stay in the air for days, so it can contribute to clouds for a long time.The sulfur-based clouds are bright, so they reflect a lot of sunlight into space. That helps keep down the surface temperature.In 2020, the International Maritime Organization passed some new regulations. It required shipping to cut sulfur emissions by 80 percent—reducing acid rain and cutting air pollution around ports.A recent study looked at the possible impact that's had on global warming. Researchers analyzed more than a million satellite images of ocean clouds. They compared those to maps of global temperature increases. And they used computer models to study what it all means.The work found a big drop in ship-created clouds. And the drop correlated with areas of greater warming. The researchers concluded that the loss of clouds could have added about a tenth of a degree Fahrenheit to global temperatures—and could add more in the years ahead.

The many creatures that dig into the sediments at the bottom of the ocean are ecosystem engineers. Their burrowing, foraging, and even pooping change the ocean landscape—not just close by, but miles away.Sediments have been described as the oceans' compost heaps. They contain bits of rock and dirt washed out to sea by rivers. They also contain bits of organic material—everything from dead skin cells to the wastes of all the fish and other animals in the water above. And they're loaded with bacteria and algae.Many organisms spend much or all of their lives near the bottom—from shallow coastal waters to the deepest ocean trenches. That includes worms, fish, crustaceans, and others.These critters dig burrows to protect them from predators or provide a safe haven for mating. They sculpt patterns in the soft sand or mud to attract mates. They poke through the sediments to scare up food. Some even scoop up the sediments, filter out tasty morsels, then poop out everything that's not edible.All of that activity changes things. It moves sediments from one spot to another. It scatters bacteria. It lifts eggs into the water. It brings nutrients to microscopic organisms.The immediate effects are on a small scale—over a few inches or feet. But they add up. Most of the sea floor is covered with sediments, and as long as there is oxygen, there are animals burrowing and moving the sediments around. So the effects of all these ecosystem engineers add up.

About 12 million tons of plastics enter the oceans every year—the equivalent of a full garbage truck every minute. The total includes millions of grocery bags. But restrictions on the bags appear to be having a positive effect. Several studies have found big reductions in the number of bags found on beaches.Plastic bags are a huge problem for ocean life. Animals can get tangled up in them. Birds and turtles mistake them for jellyfish and eat them. And fish eat bits of plastic if the bags fall apart. So reducing the number of bags in the oceans can save the lives of many creatures.One study looked at the beaches in the United Kingdom. Governments there began cutting back on the bags more than a decade ago. Some of them banned the bags, while others required stores to charge for them. Since the restrictions went into effect, the number of bags picked up on the beaches has gone down by 80 percent.There have also been big reductions in the United States. A dozen states have banned the bags, along with a couple of hundred cities and counties. Others require consumers to pay for the bags. A study by Ocean Conservancy found that volunteers picked up 29 percent fewer bags in 2022 and '23 compared to the years before Covid-19. The numbers went way up during the pandemic as bag rules were suspended.Millions of bags are still washing into the oceans. So birds, turtles, and other life still face a threat from this common form of trash.

Depending on which side of the country you live on, you probably either hate or love sea urchins. Off the coast of California, there are too many of the spiny creatures. They're destroying kelp beds, harming the entire ecosystem.But off the coast of Florida—and throughout the Caribbean Sea—there aren't enough urchins. And without them, coral reefs are dying off.Long-spined sea urchins used to be common in the Caribbean. They have black spines that can be up to a foot long. And their “teeth” are rocky plates that allow them to scrape algae from corals and other hard surfaces.In 1983, a disease raced across the Caribbean. Within two weeks, it had killed 97 percent of the urchins. And in 2022, a parasite hit the still-recovering urchin population, wiping out most of the urchins on most reefs.Without the urchins, the algae population has exploded. Algae can cover the corals, blocking the sunlight the living corals need to survive. The algae also coat the surfaces that young corals latch themselves to, preventing them from establishing new colonies.Combined with climate change, ocean pollution, and other problems, that's cut the amount of corals across the Caribbean by about 80 percent since the 1970s.Today, scientists are raising urchins in the lab, then dropping them on reefs. It's too early to tell how that's working out. But researchers are hopeful that the efforts will begin to restore balance to Caribbean reefs.

The ocean floor near Los Angeles is the largest graveyard for whales yet seen. Surveys have found evidence of more than 60 whale skeletons there. Scientists have used sonar and video cameras to map a couple of ocean basins that are centered about 15 miles offshore.Researchers have been studying the region for years, in part because it was a dumping ground for DDT and related chemicals. Scientists are seeing how that affects life in the ocean, and how it might impact human health.The most detailed mapping came in 2021 and 2023. It revealed many barrels of toxic chemicals, along with unexploded depth charges and other weapons from World War II.It also revealed seven confirmed whale skeletons, of six different species, with hints of many others—more than the total seen in the rest of the world combined.The remains of whales can feed fish and other critters for months. And, worms and microbes eventually consume even the bones. Researchers say there could be many reasons for the apparent bounty of whale skeletons. For one thing, few areas of the ocean floor have been scanned in as much detail as this one. For another, the region is packed with both whales and ships, so whales are more likely to be killed in collisions. And the deep water in the region contains little oxygen, which keeps the skeletons from decomposing.Future expeditions will continue to map the region—perhaps finding even more remains in this graveyard for whales.

The image of more than a hundred thousand aircraft carriers floating through the air might sound like a scene from a Doctor Strange movie. But the weight of all those carriers equals the amount of carbon dioxide that humanity has pumped into the air every year over the past decade or so—11 billion tons per year. The carbon dioxide traps heat, warming the atmosphere.The oceans help slow that process by absorbing about a quarter of the CO2 from the air, according to a recent report. More CO2 was being absorbed in parts of the North Atlantic and Southern Oceans.Some of the carbon dioxide is dissolved into the water as winds blow across the surface. And some is taken in by microscopic organisms, which use sunlight to convert the CO2 into food.The process is more efficient when the ocean surface is warmer. So more carbon is absorbed during El Niño years. But we've had several La Niña events in recent years, which bring cooler waters, reducing the carbon uptake.Over time, a lot of the CO2 works its way into the deep ocean, allowing the surface to absorb even more. Some of it accumulates in the sediments on the ocean floor, where it can form rocks.The extra carbon dioxide creates problems for the oceans as well. In the atmosphere it warms the water, and in the water it interferes with some creatures' ability to make their shells, for example. So those floating “aircraft carriers” are a big problem—no matter where they dock.

When a hurricane or tropical storm rolls through, most birds fly around it, or find refuge in the calm “eye” at its center. But not the Desertas petrel. It can ride out the storm, then follow the system for days—all to catch an easy meal.The petrel nests on a tiny, craggy island off the northwestern coast of Africa. There are only a few hundred of the birds, which are about the size of a pigeon. They're strong fliers: every year they make a 7500-mile round-trip to the eastern North Atlantic Ocean.Researchers attached GPS devices to 33 petrels. They tracked the birds for several weeks a year for four years. And they compared the birds' movements to the paths of six hurricanes during those periods. And they got a surprise: About a third of the birds followed the storms—something that no other ocean-going birds have ever been seen to do. Some of the petrels stuck with the hurricanes for up to five days and 1500 miles.The reason appears to be food. The hurricanes churned up the ocean, bringing water packed with nutrients to the surface. And that probably attracted some of the petrels' favorite foods: squid and small fish and crustaceans.The birds normally have to wait for night for these creatures to rise to the surface. But during the storms, there should have been an abundant supply near the surface around the clock. And the smorgasbord could've continued for days—providing a good reason for Desertas petrels to tag along.

The massive fire that engulfed Lahaina, on the Hawaiian island of Maui, killed more than a hundred people, and burned down more than 2200 buildings. And it had a much wider impact as well—on the offshore coral reef.The fire roared to life on the morning of August 8th, 2023. Fueled by drought, low humidity, and strong winds, it destroyed much of Lahaina, displacing more than 10,000 people.Ash from the fire drifted offshore and settled atop the reef. Firefighting chemicals and debris from the fire washed into the ocean as well. The contamination threatened the reef and the many creatures that live there. And any damage to the reef could heighten the human misery, because people depend on the reef for food and tourism dollars.Within days, researchers from the University of Hawaii began studying the reef system. They sampled the water, and set out water-quality sensors at key locations. They also worked with locals to catch fish from the best fishing spots. All of the samples were then analyzed for traces of contamination.Early analysis revealed high levels of copper—possibly from coatings on the hulls of boats that burned in the fire. It also showed high levels of lead. The levels of both elements have since gone down to safe levels. Zinc went up as well, and climbed even higher after heavy rains washed more contaminants into the water.Scientists continue to monitor the reef—seeing how it recovers from a human and environmental tragedy.

When beluga whales want to communicate with each other, they just use the ol' melon—a blubber-filled structure on their forehead. Researchers have found that the whales intentionally change the shape of the melon. That may convey different emotions or intentions—whether they want to play, mate, or just hang out.Belugas live in and around the Arctic Ocean. They have a thick layer of blubber to protect them from the cold. And they don't have a fin on their back, which allows them to easily glide below the ice.They use their melon to send out pulses of sound, which helps them locate prey and predators and keep tabs on their fellow whales. They produce such a variety of sounds that they're called “the canaries of the sea.”Belugas are the only whales known to change the shape of the melon. Researchers studied what the shapes might mean. They spent a year observing two males and two females in an aquarium. And they followed up with shorter looks at more than 50 whales in a second location.The scientists recorded more than 2500 melon shapes, which fit into five major categories. Almost all of the changes in shape took place when a beluga was around another whale. Many of the changes were associated with courtship, with males about three times more likely to make a change than females. But other changes were related to other social interactions, such as playing. So when a beluga has something to say, it just uses the ol' melon.

The most powerful undersea volcano ever recorded had an impact on our entire planet—from pole to pole, and all the way to outer space. And it may continue to impact parts of the world for years.The Hunga Tonga volcano is in the southern Pacific Ocean, well east of Australia. It staged a massive eruption in January of 2022. It blasted more than two cubic miles of rock and ash into the sky, and created tsunamis all across the Pacific. Shock waves in the atmosphere raced around the planet for days.Satellites and balloons recorded effects at altitudes of up to about 180 miles. The eruption rattled the ionosphere—an electrically charged region that extends well into space. That disrupted some GPS signals and radio communications.Hunga Tonga also blasted about 150 million tons of water vapor into the atmosphere. By late 2023, most of the water was still there. In fact, a layer of atmosphere a few dozen miles high contained more water vapor than had ever been seen there before.In the southern hemisphere, the combination of water vapor and sulfur from the eruption damaged the ozone layer during the winter and spring of 2023.And one study found that the aftermath of the eruption could affect the climate in parts of the world through 2029. North America could see warmer winters, while the winters in Scandinavia and parts of Australia could be colder and wetter—lingering effects of a monster volcano.

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.

Scientists in Australia are trying to paint the sea floor red. They're giving a helping hand to the red handfish—one of the most endangered fish on the planet.The fish is only three or four inches long. It's named for the fins on its sides, which are shaped like small hands. In fact, the fish uses those fins to walk along the ocean floor—it seldom swims. The hands can be pinkish brown, but they can also be bright red, along with the mouth and other body parts.Red handfish used to be common around Tasmania, a large island off the southeastern coast of Australia. Today, the population is down to about 100 adults. They're found in two small patches that are no bigger than football fields.In part, the population has dwindled because of an explosion in the number of sea urchins. Fishers have caught a lot of rock lobsters, which eat the urchins. Without the lobsters, the urchins have gobbled the kelp that forms an important part of the handfish habitat.Scientists are trying to rebuild the handfish population. In 2021 and '23, they hatched eggs in the lab, then released the youngsters into the wild. And in late 2023, they gathered 25 adults from the ocean and housed them in tanks. That was to protect them from a “marine heatwave” that could have killed off some of the fish. They, too, were scheduled to be returned to their ocean homes.These efforts could help the red handfish survive—adding some splashes of color off the coast of Tasmania.

A massive hailstorm blasted northeastern Spain a couple of years ago. It lasted only 10 minutes or so. But it produced the largest hailstones ever recorded in the country—the size of softballs. It might have been kicked up a couple of notches by another type of “weather” event—a marine heatwave.The storm roared to life on August 30th, 2022. It caused major damage to roofs, cars, and crops. It injured 67 people, and killed a toddler, who was hit in the head by one of the giant hailstones.A recent study blamed the intensity of the storm on global climate change. Scientists simulated climate conditions under different levels of air and ocean warming.The storm took place during a marine heatwave in the western Mediterranean Sea. The surface water temperature topped 85 degrees Fahrenheit—five degrees higher than normal. That produced more evaporation, which fed extra moisture into the air. It also heated the air, providing the energy to build storm clouds. As hailstones developed, strong updrafts pushed them back up, so they just kept getting bigger and bigger. Finally, they became heavy enough to plunge to the ground—causing chaos.The study said the hailstorm itself could have happened without today's higher temperatures. But it would not have been as intense or as destructive.Major hailstorms have been getting more common across Spain and the rest of Europe. And the study says that trend should continue—powered by our warming climate.

Many gardeners use clam shells as decorations. But not many garden the clams themselves. Yet clam gardens can yield more clams than untended shorelines, provide more species diversity, and even protect the clams from the acidity in today's oceans.Clams were gardened as early as 4,000 years ago by the people of the Pacific Northwest, from Alaska to Washington. In some regions, the gardens lined the entire coastline.The gardens consisted of short walls built along the shore, forming enclosures, with terraces behind the walls. Water flowed in, and some of it was trapped as the tide rolled out. That provided habitat for littleneck and butter clams.The gardens were abandoned after European settlers moved in. But research over the past decade shows that the gardens were highly effective. They could produce up to twice as many littleneck clams as uncultivated areas, and four times as many butter clams. The gardens also attracted other life, including seaweed and sea cucumbers, providing a more diverse diet for the gardeners.Gardens also contained a lot of clam shells, which provide the minerals clams need to make new shells. That's especially important today, because higher levels of ocean acidity make it harder for clams to produce shells.The Swinomish people of Washington have recently built new clam gardens. They produce food, provide a training ground, and give scientists a place to study the gardens and their “crops”—butter and littleneck clams.

Life along the American coastline has been getting more perilous. Earth's warming climate is causing a rise in sea level, an increase in major hurricanes, more marine heatwaves, and many other problems. That costs time, money, and lives. And things are expected to get even worse in the decades ahead.A new national climate assessment, issued in late 2023, forecasted that sea level will rise an average of almost a foot from 2020 to 2050. That equals the total rise over the past century. As a result, the report says that coastal flooding at high tide should happen 5 to 10 times more often. Erosion will wash away beaches and bring cliffs tumbling down. And some hurricanes will become far more destructive.The assessment says the combination of the changing climate and human adaptations, such as more seawalls and levees, will make it more difficult for coastal ecosystems to adapt. Such ecosystems function as buffers against tropical storms, help control erosion, and provide habitat for fish and other organisms.The report says that some actions now may help minimize the impacts of climate change and human adaptations in the future. Restoring coastal habitat is one of the most important. Cities and towns can also beef up their infrastructure—moving roadways and improving stormwater systems, for example. And they can start planning to relocate people and buildings to less-hazardous areas—to meet the growing threat of climate change.

Thresher sharks are some of the “snappiest” fish in the oceans. They have an oversized tail fin that looks like a scythe—and is almost as deadly. A shark “snaps” the fin like someone snapping a towel in a locker room, stunning its prey. And a recent study worked out some of the details on how the shark does it.Threshers are found around the world. Most stay fairly close to shore, and not very deep. Adults can grow to about 20 feet long.What really sets them apart is that snapping motion. A shark first winds up a bit like a baseball pitcher. It twists its body in one direction, its tail in the opposite direction. The tail, which is almost as long as the body, is held high. The shark then uncoils, snapping the tail around in a fast, powerful motion. It then takes a minute to relax before grabbing its prey.Researchers recently studied the spines of 10 thresher sharks that had stranded on shore or been caught by anglers. The sharks ranged from an embryo to an adult 13 feet long.The scientists did CAT scans on the sharks, revealing the structure of the shark spines and vertebrae. The work showed that the vertebrae in the body are longer and thicker than those close to the tail—a trait that developed as the sharks got older. The interiors of the two types of vertebrae were different as well.The researchers said the differences may make a thresher more flexible while adding strength to its tail—allowing the sharks to “snap up” their dinner.

It may sound surprising, but many mountains are hiding from us—some of which may be more than a mile high. Scientists are finding more of them all the time, though—at the bottom of the sea. A research cruise in 2023, for example, found four of them in the Southern Ocean.The scientists were studying the Antarctic Circumpolar Current, which circles around Antarctica. It's the strongest ocean current in the world. It prevents most of the warm water from the other oceans from reaching Antarctica. But some warm water sneaks through. That makes the Antarctic ice melt faster, speeding up the rise in global sea level.Researchers were looking for these “leaks,” and studying how the warm water was flowing around Antarctica. As part of their work, they used sonar to scan a 7700-square-mile patch of the ocean floor. They also used an orbiting satellite to look for small “bumps” on the surface that indicate the presence of mountains.They found a chain of eight mountains, called seamounts. They're extinct volcanoes that formed within the past 20 million years. Some of them were already known, but four had never been seen before. The tallest is almost a mile high.The mountain range is in the middle of the Antarctic Circumpolar Current. As the current flows over and between the mountains, it forms turbulent patches that break off as eddies. Those whorls can disrupt the current, allowing warmer water to punch through—helping thaw out the frozen south.

When you build a house, it affects the surrounding ecosystem. The same thing applies to houses built by fiddler crabs in salt marshes. Their burrows can help or hinder the surrounding plants, affect the flow of water, and perhaps cause the marsh to send more greenhouse gases into the air. Thanks to all of that, fiddlers are sometimes described as “ecoengineers.”Fiddler crabs are only about an inch across. They're found in salt marshes all along the coast. They dig burrows that can be long and deep. The burrows protect the crabs from predators and the environment. They also give the crabs a place to mate. In fact, the quality of a burrow plays a role in a female's pick of a partner.The burrows pass below the marsh grasses. They can form networks that allow water and nutrients to flow through the marsh. They can “aerate” the soil, increasing the growth of the grass—something that can boost the discharge of greenhouse gases from microbes in the soil. But if the burrows are too extensive, they can damage root systems, slowing growth.A recent study simulated these effects with computers. The work showed that a lot of their impact may depend on the details of the burrows themselves—their depth and shape, the number of entrances, and more. Burrows that are deeper and have more “doors” may increase the exchange of water between aquifers and the surface, for example—changing the ecosystems around these small but abundant houses.

In 1875, Navy lieutenant commander Charles Dwight Sigsbee and his ship, the George S. Blake, began a journey into the history books. They started measuring the depth of the Gulf of Mexico with a mechanism that Sigsbee created. When the job was finished three years later, the ship had measured the entire Gulf—the first ocean basin to have an accurate map of all its contours.Sailors had been measuring depths for centuries. They threw a rope with a heavy weight on the end into the water. Distances were marked on the rope every few feet. Counting the marks revealed the ocean depth.The technique became known as depth sounding. Crew members would “sound off” the depth as the rope played out. But it wasn't especially accurate—especially for deep water. But it improved in the mid-19th century. Sir William Thomson of England developed a machine to do the job, using piano wire on a motorized spool.Sigsbee refined that design. He made the machine larger and more stable, and replaced the piano wire with steel. That improved accuracy. His device became known as the Sigsbee sounding machine. And it was the standard for measuring depths for 50 years.Scientists named many of the features mapped by the Blake after its commander. So maps of the Gulf of Mexico show the Sigsbee Escarpment, Sigsbee Abyssal Plain, and Sigsbee Deep—the deepest spot in the Gulf—first recorded by Sigsbee's machine a century and a half ago.

Olive trees are sprouting all across the Balearic Islands—a chain off the Mediterranean coast of Spain. The largest island, Mallorca, has more than 800,000 cultivated trees. They yield a good portion of the world's supply of extra virgin olive oil.More trees—of both wild and cultivated varieties—have been showing up on the surrounding islands. They've been planted not by farmers, but by sea gulls. The gulls eat olives—especially those from Mallorca—then fly miles over the Mediterranean to their home islands. Once there, they spit up the olive pits, which can sprout and grow trees.Biologists recently studied yellow-legged gulls, which are common across the Balearic Islands. The scientists brought some of the birds into the lab, and attached GPS trackers to others. They also examined the populations of olive trees in the islands.The researchers found that the birds ate both wild and cultivated olives. But they preferred the ones raised on farms. On average, they flew about three miles farther to get them—about eight miles per trip, although some gulls flew more than 60 miles.The gulls upchucked most of the olive pits on the rocky outcrops where they nest. But many of the pits were dropped where they could produce trees. On one island, an area that had been mostly grass and shrubs was being transformed into an olive grove, with both wild and domestic varieties—thanks to the wings and appetites of yellow-legged gulls.

The classic example of chaos theory is called the butterfly effect: If a butterfly flaps its wings over China, it creates ripples in the air that might eventually trigger storms over the Americas. Something similar may be playing out over the South China Sea and the surrounding land: Changes in climate conditions there may influence the rest of the world.The South China Sea covers almost one and a half million square miles. It's bounded by Southeast Asia and the islands of the Philippines and Indonesia. Influenced by climate change in Asia, its waters are warming faster than most of the world's oceans.Scientists say that's influencing conditions not only across the region, but worldwide. There's more evaporation from the warmer waters, which is changing circulation patterns in the atmosphere above it, for example. These patterns interact with others. That creates a ripple effect that can travel around the globe—like the ripples caused by that pesky butterfly.Climate models suggest possible impacts on specific regions as the South China Sea and the surrounding area get even warmer. The timing and strength of El Niño and La Niña might change, for example. Ditto for the monsoons in Asia. The Americas might see greater extremes in temperature and precipitation, parts of Asia might have more spring and summer droughts, and sea ice could change in both the Arctic and the Antarctic—some possibly chaotic results of our changing climate.

If you're afraid of the dark, you should avoid the “midnight zone” in the oceans. It's so far down that no sunlight ever reaches it. The zone's inhabitants include creatures with bulging eyes and big, sharp teeth, and some with bright, wiggling “lures” to attract prey.One inhabitant also looks like the stuff of nightmares, but it's a threat only to small fish and other tiny creatures: Stygiomedusa gigantea—the giant phantom jelly. Its “body”—known as a bell—is about three feet across. It can expand to several times that size, though, perhaps to wrap up its prey.Four “arms” trail away from the bell. They can be more than 30 feet long, and they wave through the currents like a ripped-up bedsheet in a summer breeze.The arms are classified as “mouth” arms—they sense prey in the dark ocean, then grab it and pull it up to the stomach. But unlike many jellies, the arms don't have stingers.The giant phantom jelly has been spotted in all the world's oceans except the Arctic. But it's not easy to see because it usually stays deep—anywhere from a few thousand feet to about four miles. In fact, since the first one was reported, in 1899, scientists have logged only a few more than a hundred confirmed sightings.Despite the lack of sightings, biologists say the giants may be common—but hidden in the dark waters of the midnight zone.

In a classic Jules Verne novel, the submarine Nautilus travels “20,000 leagues under the sea.” You might think that “20,000 leagues” indicated the sub's depth. But you'd need a really deep ocean for that: a league is three miles, so 20,000 leagues is 60,000 miles. The title tells us how far the Nautilus traveled through the oceans.Over the centuries, sailors and mapmakers created new units of measure, with new words to describe them, for plying the world's oceans. Some of the words have been heaved overboard, but some are still in use.One of the lesser-used units is the fathom, which does indicate depth. It comes from a word in Old English that means “outstretched arms.” That's because a fathom originally was based on the span of a man's fully spread arms. Eventually, its length was set at six feet. So the deepest point in the ocean is 6,000 fathoms down.One unit that's still in common use is the nautical mile—1.15 land-based miles. It marks the size of one minute of latitude—the location north or south of the equator.And it's the basis for the word knot: one knot is one nautical mile per hour. It originated in the 17th century. Sailors estimated their speed by throwing out a piece of wood attached to a rope. Knots were tied in the rope at specific lengths. Sailors counted the number of knots that spooled out over a given time—a knotty way to measure speed.

The telescopefish has a cast-iron stomach. Not only can the stomach digest prey that's bigger than the telescopefish itself, but it's as dark as cast iron. That prevents the fish's prey from getting revenge by attracting critters that might eat the telescopefish.There are two known species of telescopefish. Members of both species are small—no more than about six to eight inches long. They're found in fairly warm waters around the world, at depths of a third of a mile to a mile and a half or so.Little or no sunlight reaches that far down. So the fish has developed sensitive eyes that poke outward from the head like a pair of binoculars or long telescopes—hence the name “telescopefish.” It may use those peepers to see the faint silhouettes of prey above it. It may glide through the water vertically so it can keep its eyes aimed upward. In addition, it can see fish and other prey that produce their own light, shining through the darkness.When it spies a meal, the telescopefish grabs hold with a mouthful of sharp teeth. It can extend its jaw so wide that it can swallow prey up to twice its own size.Such big prey are folded in half inside the stomach. But the telescopefish is translucent, so its glow-in-the-dark meals might attract the attention of predators. To prevent that, its stomach is black and opaque—like a blackout curtain or a cast-iron skillet. So its prey remains hidden—protecting the telescopefish in the dark ocean depths.

From poetry to music to movies, we're always hearing about the “deep blue sea.” But the seas aren't always deep blue. And sometimes, they're not blue at all. They can be green, brown, or other colors. And each color can tell us something about what's happening in that part of the sea.Understanding what the colors are telling us is one goal of PACE—Plankton, Aerosol, Cloud, Ocean Ecosystem—a NASA satellite that launched in February.[3, 2, 1, booster ignition ... Full-power engines and liftoff of the Falcon 9 and PACE—helping keep pace with our ever-changing ocean and atmosphere...] The mission is studying how the oceans and atmosphere interact, tracking their health, charting marine resources, and more. And ocean color plays a big role in all of that.The water can be tinted by tiny organisms known as phytoplankton. Some of them turn the water green—a result of the chlorophyll they use to convert sunlight to energy. Plankton attract fish and other large animals. So keeping an eye on the color can help scientists track the health of fisheries.Massive blooms of some types of algae, on the other hand, can stain the water brown or red. They may use up much of the oxygen in the water, turning a region into a “dead zone” where not many other organisms can live. They can also produce toxins that make shellfish dangerous to eat. So tracking the blooms—by looking for their colors from space—can help keep people safe.

For the seagrass beds of southern Texas, rising sea level may be a case of give and take—or make that take and give. Higher waters are killing off some seagrass. But as the water rises even higher, newly submerged land has the potential to increase the total seagrass area.Seagrass is important for many coastal ecosystems. It can protect the coast from storms, filter pollution from runoff, and provide habitat and food for fish and other life. So losing seagrass is a big deal.Researchers at the University of Texas Marine Science Institute studied beds in Upper Laguna Madre—a narrow estuary behind Padre Island. They looked at the beds today, and examined records from the past three decades.Sea level in the region is rising much faster than the global average—roughly half an inch to an inch per year. As the water rises, less sunlight reaches the bottom—a big problem for seagrasses. Because of the deeper waters, two species of seagrass have vanished since 2018 at one study location. A check on a wider area showed that seagrass had disappeared at almost a quarter of the sampled locations.On the other hand, seagrass may colonize newly submerged regions. That could expand its total habitat by as much as 25 square miles by 2050.Not every seagrass habitat will be that prolific. Beds in much of the world are hemmed in by development, so they have no place to go. For those regions, there won't be much give and take—rising sea level will be all take.

The “beards” of marine mussels aren't just a fashion statement. They anchor the mussels to the sea floor, attach to each other to form large “beds,” and hold out potential invaders. They're also playing a role in materials research—scientists study the beards to learn how to make water-proof glue for many applications.The beards consist of a bundle of about 20 to 60 threads known as a byssus. The threads radiate outward from the mussel's “foot.” Each thread is tipped with a biological superglue—a combination of proteins from the mussel and metals from the water.Mussels use the byssus to anchor themselves to the bottom, where they wait for tiny prey organisms to float through their shells. The threads are strong but flexible, so they allow the mussels to sway with the tides. The glue never dissolves in the water. The mussels can use the threads to move along the bottom; they anchor one thread, then “reel” it in to shift position.When the mussels are threatened, though, they let go in a hurry. Tiny hairlike structures on the bottom of the foot beat rapidly, detaching the byssus from the mussel's body. The mussel grows a new one in just a few hours.Scientists are studying the byssus to help develop ways to attach sensors or implants to the human body. They're also looking for ways to overcome the glue to prevent mussels—especially freshwater species—from fouling underwater outlets or other structures—getting free of some “sticky” threads.

Early in World War II, the Navy began using sonar to probe for enemy U-boats. Ships would send out pulses of sound, then measure their reflection to figure out what was below. But early observations revealed something a little disconcerting: The ocean floor wasn't where it was supposed to be—it was a lot closer to the surface. Sonar operators thought they might be seeing uncharted underwater islands.But scientists soon came up with another explanation. Sonar was revealing a “false bottom”—a layer with so many small fish and other organisms that it was reflecting the sonar. It was named the deep scattering layer.It's found in most of the world's oceans, generally at depths of a thousand to 1500 feet. It's part of the daily migration of the critters that live there.During the day, they go deep because little or no sunlight penetrates that far. That allows them to hide from predators—most of the time. Dolphins and other predators sometimes dive through the layer, scooping up some tasty treats. The schools of fish, squid, and crustaceans bunch closer together when they're attacked.At night, they rise close to the surface, where they feed on tiny organisms. At dawn, they start back down again.The main inhabitants of the scattering layer are lanternfish. They're only a few inches long, but they're plentiful. Their swim bladders are especially good at reflecting sonar—creating a false bottom in images of the deep ocean.

Pufferfish in Japan are known for one thing. They're a delicacy that can be deadly. Their organs contain a highly toxic compound that can kill in minutes. But one species of pufferfish has a different distinction: Its males might be the most creative artists in the oceans.In 1995, divers off the coast of Japan saw an unusual pattern in the sand on the ocean floor—a circle with small peaks and valleys radiating out from a flat center. It wasn't until 2011 that marine scientists could explain them: the creations of a species known today as white-spotted pufferfish.The fish is only a few inches long, but its creations can span more than seven feet. They're nests—sculpted by males to attract females.The male begins the process by creating a circle. He swims back and forth across it, flapping his fins to carve ridges and valleys. They radiate outward from the center in near-perfect lines. The fish then creates smaller ridges inside that structure, with a flat area in the middle. Finally, he adds bits of shell and coral. The whole process takes seven to nine days.When the nest is about ready, a female swims up to it. If she enters, the male rushes toward her. If the female likes the set-up, she lays her eggs in the center—then vanishes. The male spends up to six days protecting the eggs as the nest slowly erodes in the currents. He doesn't shore it up. Instead, after the young'uns are gone, he starts a new one—a new work of art at the bottom of the sea.