Science and the Sea podcast

People are always looking for ways to make things brighter and whiter—from teeth to laundry. They seldom think of brighter, whiter clouds. Yet whiter clouds are just as important as whiter bicuspids or T-shirts. They reflect more sunlight back into space, making our planet cooler.In recent years, scientists have discovered a great cloud whitener: tiny organisms known as phytoplankton. They’re especially abundant in the Southern Ocean—the waters around Antarctica. Satellites reveal that clouds in that region are much whiter than those elsewhere.Clouds form when water vapor condenses around tiny particles high in the atmosphere, forming droplets. The brightness of the clouds depends on the number of droplets packed into a given area. A lot of small droplets makes brighter clouds than a smaller number of large droplets.Phytoplankton use sunlight as an energy source, so there are big “blooms” of them in the southern summer. A recent study found that the blooms correspond to an increase in the number and brightness of clouds.The phytoplankton emit particles of a sulfur compound that climb high into the atmosphere, where they form the “seeds” for small water droplets. The small droplets make more and brighter clouds. Since the clouds reflect more sunlight, they keep the Southern Ocean cooler.Climate change could reduce the number of phytoplankton—perhaps leading to dingier clouds in the far south—and higher temperatures everywhere.

When you bite into a chewy bagel, crunch a crispy taco, or grind up a piece of tough meat, you’re using structures that evolved hundreds of millions of years ago: teeth.There’s no consensus on how teeth first formed. One idea says they formed from structures inside fish or perhaps other animals. The other says they formed from the scales of fish that resembled modern-day sharks—400 million years ago.The scales of sharks and rays are made of a material similar to that found in teeth—theirs and ours. The scales of ancient sharks and rays were similar. Since the scales end around a fish’s mouth, that suggested that the scales basically “migrated” into fish mouths.That would’ve provided a big advantage for the first fish with teeth. Early teeth were used to grab and hold prey, so a meal couldn’t simply wiggle away. The ability to chew came later.A study released in late 2022 supports that “outside-in” idea of tooth evolution. Scientists studied the fossils of sawfish that lived 70 million years ago. They used an electron microscope to scan the scales that form the “spikes” on the edge of the fish’s long snouts. And they found that the material inside the spikes was basically the same as the enamel in modern teeth. The researchers suggested that it wouldn’t be a big step for true teeth to evolve from those scales.The origin of teeth is still far from settled. But if they came from fish scales, then we have something in common with sharks.

Hurricane Ian slammed into southwestern Florida in September 2022. It produced a storm surge up to 15 feet high, and dumped a foot or more of rain across the region. That killed dozens, damaged or destroyed thousands of buildings, and caused tens of billions of dollars in losses.Floridians are still evaluating another form of damage—the spread of plants and animals beyond their usual habitats. Flooding and the storm surge brought water in from the Gulf of Mexico, and caused lakes and rivers to overflow their banks. The water acted like a superhighway, allowing organisms to travel far from home.The U.S. Geological Survey estimated that almost 200 species could have been relocated. Some of them were living in the bays and estuaries, while others were in freshwater areas. Among the affected species are frogs, crabs, fish, shrimp, turtles, and plants. The list includes pythons, which were already spreading far and wide across the region.The resettling of species can cause all kinds of trouble. Newly introduced species can eat up or crowd out existing species, altering an entire ecosystem. New species can also damage infrastructure—clogging pipes, fouling boats, and causing other mischief. And some species can be dangerous to people—think alligators that suddenly find themselves in a new environment.Scientists and non-scientists alike are still keeping their eyes open—for plants and animals relocated by a powerful hurricane.

The final battle of a war between Rome and Carthage sent many warships to their doom. Scientists have pulled up artifacts from some of those vessels. And at least one of the artifacts became a busy home for life. Biologists found evidence of more than a hundred species—clams, worms, snails, and others—a record of how life colonized the artifact over the centuries.The battle took place in 241 BC. It was in the Mediterranean Sea, off the coast of Sicily, a large island near the toe of Italy’s “boot.” Rome was blockading the island. Carthage sent a fleet to break through, but Rome won the battle—and the war.In 2017, scientists recovered several artifacts from that site. One was a ram—a hollow bronze object attached to the front of a ship. It was used to ram through the sides of enemy boats. The ram is three feet long, and weighs 375 pounds.The ram was restored in 2019. Workers preserved all the evidence of life. Biologists then sifted through that material. They cataloged 114 species. Some inhabited the ram, while others were pieces of shell or other hard bits that had been carried into the ram by the currents.The organisms came from several nearby habitats, including seagrass beds and both muddy and rocky sea floors. Some of the species were mobile, while others were stationary—probably washed up by the currents. They reflect the life across a wide area of the Mediterranean—and across more than two millennia.

There are lots of ways for a fish to attract its prey. The batfish uses two ways. It dangles a lure over its head, which pulls the prey in close. It then squirts a fluid into the water that completes the job—it pulls the prey close enough for the batfish to grab it.Batfish—also known as seabats—are odd little creatures. They have wide, flat bodies. Seen from above, they can resemble garden spades or pancakes. They’re fairly small, and they live on the bottom of warm oceans and seas around the world.Batfish are terrible swimmers. But some of their fins act like legs, so the fish amble across the bottom. Their gait resembles that of a bat walking on its elbows—hence the name.Batfish are a type of anglerfish. Most anglerfish have a lure on their heads. Many of those lures glow. As the anglerfish swims along, the lure sways back and forth, catching the attention of possible prey.The lures of batfish are different. For one thing, the batfish can reel in the lure, storing it out of sight. And for another, the lure doesn’t glow. Instead, it’s shaped like something the batfish’s prey might like to eat. That pulls the prey close. The fluid finishes the job, attracting shrimp, crabs, snails, and small fish.There are about 60 species of batfish, including the polka-dot batfish; the pancake batfish, which looks like a pancake with legs; and the red-lipped batfish, which looks like it’s wearing clown makeup—all of them “ambling” across the bottom of the sea.

As if hurricanes aren’t scary enough, they can generate something that sounds just as scary: stormquakes. As a hurricane rumbles across the ocean surface, it can cause the ocean floor to rumble as well. Fortunately, the quakes don’t cause any damage.Scientists discovered stormquakes by studying seismic activity recorded during many hurricanes. The records revealed that sometimes, the ocean floor “jiggled” as a hurricane passed overhead. The jiggles could be as strong as a magnitude 3.5 earthquake. Some continued for days, and were felt up to thousands of miles away.A stormquake rumbles to life as a hurricane churns up big waves on the ocean surface. That creates big waves below the surface. They can ripple all the way to the bottom. And that can create waves in the ground. But it takes the right ocean contours to make the bottom rumble. The stormquakes found so far all took place in regions with a shallow continental shelf with a gentle slope. The ground was fairly flat and smooth.So most of the stormquakes identified so far have been limited to a few areas. They’re common off the coast of New England and the Atlantic provinces of Canada, in areas like the Georges Bank and the Grand Banks. They’ve also been recorded off the coast of Florida.The seismic waves created by stormquakes aren’t a threat to life and limb. But they can help scientists probe conditions below the ocean floor—the rumble of hurricanes pushing deep into the solid Earth.

Whale sharks are a bit like pop stars: They attract a crowd. Smaller fish swarm around them. That’s probably a better deal for some fish than others. Sometimes, predators can wolf down entire schools of the groupies in a matter of seconds.Whale sharks are the largest fish on Earth. They can span 25 feet or more. They’re filter feeders—they filter tiny fish and other small organisms from the water as they swim along with their mouths wide open.The sharks often are accompanied by other fish. That includes a hodge-podge of smaller fish known as baitfish. They’re a few inches long, and there can sometimes be so many of them that they look like a shimmering cloud around a shark.Biologists have speculated that one reason the baitfish hang out near the whale sharks is protection—predators might keep their distance from the giants. But a recent study in Australia found otherwise.Scientists analyzed video shot over several years. The pictures showed larger fish gobbling up the baitfish. Most attacks lasted no more than about 20 seconds, with no or few survivors.That leaves a couple of other explanations for why the smaller fish hang around the sharks. They might get a bit of a free ride—either riding the wave that forms ahead of the shark, or “drafting” behind it like a car following a big truck. Also, the smaller fish eat the same food as the sharks, so the whale sharks might take them to good hunting grounds—the good part of swimming with sharks.

When we talk about “falling asleep,” we don’t usually mean it literally. For Northern elephant seals, though, it is literal—they sleep while falling through the ocean. You can’t help but wonder if they dream about falling, too.Northern elephant seals live along the coast of California. They can be up to 13 feet long, and weigh a couple of tons. The seals spend seven or eight months a year at sea, foraging for food. They spend the remaining months on shore, where they breed and rest up for the next year’s journey.When they’re on shore, they sleep for 10 hours a day or longer. But researchers in California wondered how they slept at sea. So they strapped “swimmer’s caps” on the heads of 13 young females in Monterey Bay. Instruments recorded depth, motion, and heart rate. And for the first time, they also recorded brain activity.Those recordings showed that the animals took “power naps” of about 10 minutes. At depths of several hundred feet—below the “danger zone” where they’re likely to come across predators—the seals stopped, began to glide, then fell into a deep sleep. While they slept, they spiraled downward like leaves fluttering from a tree. After catching a few Zs, the seals woke up and swam to the surface.The researchers compared their findings to depth and motion profiles obtained from hundreds more seals over the decades. That showed that ocean-going elephant seals sleep just two hours a day—a few power naps to keep them going.

The bodies of most fish are scaly. The scales protect them from predators and rough surfaces, improve streamlining, and ward off diseases and parasites. But a few species have different forms of protection: tough skin, bony plates, or thick layers of slime.Scales vary in size, shape, alignment, and structure. The bodies of most sharks, for example, are covered by rows of tiny, pointed scales that aim toward the tail. The scales of tarpon, on the other hand, are round and can be more than two inches across.Scales are especially helpful for marine biologists. The scales grow throughout the fish’s life. Each year of growth is bounded by a dark ring, allowing scientists to determine a fish’s age. They can also analyze the scales to learn more about a fish’s growth rate, diet, and its environment from year to year.The list of fish without scales is pretty short. It includes hagfish and lampreys—odd-looking critters that are covered in a thick layer of slime. Hagfish can shed that layer if they’re attacked, allowing them to simply slip away. The slime produced by clingfish contains a toxin that can kill other fish.Moray eels have an especially thick skin. It’s covered with slime-producing cells, providing two layers of protection.And a skinny species known as razorfish, which floats nose-down, is covered by bony plates that extend all the way to the tail, ending with a sharp spine.So these and other “naked” fish have good protection even without scales.

Life in arctic waters is like a giant see-saw. Some species rise to the surface during the day and sink into the depths at night, while others do just the opposite. And the see-saw keeps tottering even during the winter, when there’s no sunlight at all.But research over the past couple of decades suggests that things could be changing. As the climate warms up, the arctic ice gets thinner. That allows more ships to ply the winter waters. It’s also making it easier to develop the coastline. And all of those ships and buildings are lighting up the night.A couple of decades ago, scientists discovered that tiny organisms known as zooplankton continue their up-and-down motion even during the winter. The organisms stay active, helping everything else roar back to life in spring and summer.But the organisms scoot away from artificial light sources. So do fish. Increased light in the years ahead could interrupt the natural rhythm of the ocean, perhaps with dire consequences for all life.Scientists in Norway are studying the effects of winter lighting through a project called Deep Impact. They’re comparing how marine creatures respond when research vessels are dark versus when they’re well lit. And they’re deploying packages of instruments with nicknames like Fish Disco, which sets off flashes of multi-colored lights.The research should tell us more about how life in the Arctic Ocean will respond to brighter winter skies—a result of our warming climate.