Science and the Sea podcast The University of Texas Marine Science Institute

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.

As Earth gets warmer, scientists expect to see some changes in hurricanes. There might not be more of them, but the strongest ones might be much more intense.
To better understand what might happen, scientists are digging deep into the past. They’re looking at how often especially powerful hurricanes made landfall when climate conditions were similar to what we’re seeing today.
One study looked at sediments found in a lake and a pond in the Florida panhandle. Both of them were far enough inland that they weren’t affected by smaller storms. But they were close enough to the Gulf of Mexico to be impacted by major storms.
Big storms moved sand into the lake and pond, forming layers. The details of the layers revealed the intensity of the storms. And the depth of the layers revealed when the storms happened.
The study found that monster storms—category four or five—were much more frequent from about the year 650 to 1250. That jibes with studies made at other locations. The water at the surface back then was warm, and the warm layer extended deeper than average. Winds were more favorable for big storms, too.
After that, the Gulf calmed down. Only one known category five storm has made landfall in the panhandle since that era—Hurricane Michael, in 2018.
These and other results should help scientists prepare for what we may see in the future—the potential for more monster hurricanes.

Until 2011, no one knew that a couple of groups of dolphins found along the coast of southeastern Australia were a separate species from all other dolphins.
Burrunan dolphins are related to the two other known species of bottlenose dolphins. There are two groups of Burrunans—about 250 dolphins in all.
But today, no one knows how much longer the species might be around. It’s critically endangered. And it’s threatened by several hazards, including industrial chemicals. In fact, the species contains higher levels of one group of chemicals than any other dolphins in the world.
In a recent study, biologists tested 38 dolphins, of several species, that were found on the shore. In particular, they looked for a group of chemicals known as PFAS. They’re used in food packaging, firefighting foam, and non-stick cookware. They’re known as “forever” chemicals because they never break down. They wash into the sea from industrial and wastewater treatment plants, and runoff from the ground.
The scientists found high levels of PFAS in all the dolphins. But by far the highest levels were in the Burrunans—10 times the concentration thought to cause liver problems and other health issues. And one dolphin had the highest level of the chemicals ever measured in any dolphin anywhere in the world.
The Burrunans eat fish, which have high concentrations of the compounds in their livers—increasing the danger for a rare and endangered species of dolphin.

“Million Mounds” may be overstating the case a bit, but there’s no doubt it’s one of the most extensive deep-water coral reefs on the planet. Or make that part of one. Scientists recently discovered that the system extends far beyond Million Mounds—the biggest deep-water coral reef yet seen.
The entire complex stretches along the southeastern Atlantic coast of the United States. It’s a few dozen miles out, from Miami to near Charleston. It encompasses about 50,000 square miles, at depths of about 2,000 feet or greater.
Million Mounds had been the only part of the system that had been studied in detail. Most of the corals are on the many mounds and ridges found across the region—hence the name “Million Mounds.”
Scientists used ships on the surface, plus robotic submersibles, to map a much larger region. The surface vessels scanned the ocean floor with sonar. And the submersibles provided close-up looks at selected locations.
The corals aren’t like the vibrantly colored ones found in shallower seas. Instead, they’re all white. That’s because they’re mainly the “stony” part of a coral. They don’t contain the same microorganisms that provide the color for their shallower cousins. Those organisms need sunlight, and it’s too dark for them in the deep ocean.
The deep-water coral filter food from the water—bits of organic matter that drift to the bottom. That allows them to survive—a lot of them—in the deep waters off the American coast.

For a tiny marine worm found in the Bay of Naples and elsewhere, life ends in a frenzy. The worms lose a lot of their internal organs, their eyes get bigger, and they rise to the surface. There, as they paddle furiously, they release sperm and eggs, creating the next generation. And it’s all triggered by moonlight.
The worms are one of more than 10,000 species of marine bristle worm. They’re only about an inch long. Each body segment has a pair of paddle-like structures tipped with bristles. The worms live at the bottom of warm, shallow waters around the world. And they’re considered “living fossils”—they haven’t changed much in tens of millions of years.
The bristle worms are especially sensitive to changing light levels. They build tubes on the ocean floor. When a shadow passes across them, they pull back into the tubes to elude possible predators. And their end-of-life ballet is triggered by moonlight.
The body changes begin around the time of “new” Moon, when there’s little or no moonlight. The worms then rise to the surface not long after the full Moon.
Scientists recently studied how that happens. They found that some proteins react differently with different light levels. Under bright sunlight, they stay apart, in separate units. But under dimmer conditions, the units stick together. That allows the worms to not only distinguish between day and night, but between different phases of the Moon—a light-activated “trigger” for a big change.

Conditions in the Arctic Ocean may be about to switch gears. That could mean that Arctic waters would become more like those in the North Atlantic—a process known as “atlantification.” As a result, sea ice would disappear a lot faster than it has in recent years.
The rate of sea-ice loss peaked in 2007. The total amount of ice is still going down, but much more slowly than it was before. In December of 2023, in fact, the sea ice increased at a higher rate than in all but two other months in the past 45 years.
A recent study said the slowdown in ice loss may be a result of the Arctic dipole—a pattern in the way air circulates over the far north. Today, there’s high pressure over the Canadian arctic, and low pressure over Siberia.
That pattern reduces the flow of warmer water from the North Atlantic Ocean into the Arctic Ocean. There’s a thicker layer of colder, fresher water at the top of the Arctic. That keeps the ice from vanishing as fast as expected based on the higher air temperatures produced by our warming climate.
Scientists looked at decades of observations made from ships, airplanes, and satellites. They found that the dipole might be about to flip over—from “positive” to “negative.” If that happens, the changing circulation in the atmosphere would allow more water to flow in from the Atlantic. That would warm the upper layers of the Arctic, causing sea ice to disappear much faster—boosting the “atlantification” of the Arctic.