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

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.