It’s easy to take bacteria for granted when these single-celled creatures are too small to see with the naked eye. Yet bacteria are the most plentiful living organisms on earth and play a huge role in maintaining ecosystems. The population of one group, called SAR11, in the world’s oceans is estimated to be around 24,000,000,000,000,000,000,000,000,000! (That’s 27 zeros.) SAR11 bacteria make up about 20% to 40% of plankton cells in upper layers of the ocean.

Scientists have learned that the very characteristic that’s helped these bacteria survive so well also makes them extra sensitive to unexpected changes in the world’s oceans. So far, the secret to SAR11’s evolutionary success has been their ability to adapt to environments with very few nutrients. They do this by getting rid of genes they don’t need. This helps them conserve energy when food is scarce. When scientists recently looked at the genes of hundreds of these bacteria, they learned which genes tended to be lost. The missing genes were the ones that regulate the cell cycle and ensure that cell division and replication of DNA occurs normally. The strategy of losing those genes is effective if the surrounding environment remains fairly stable. But oceans have been in a state of ongoing flux in recent years due to effects of shifts in the global climate on ocean temperature and pH levels.

Under that stress, these bacteria are replicating DNA without dividing properly. They end up with extra chromosomes and then grow too big and die—even when nutrients become more abundant. That’s bad news for more than just SAR11. These bacteria are important in regulating marine food webs, so environmental instability affecting them could have far-reaching consequences for many other creatures. Learning more about this vulnerability can help scientists understand what to expect as conditions in the oceans change.

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Beaked whales are among the hardest whale species to find because they dive deeper than any other mammal (some reaching almost 10,000 feet deep), they only surface for a couple minutes at a time, and are especially wary of boats. But knowing where they live is important so the military can avoid going there for sonar exercises, which hinder the whales’ feeding and can cause severe injury. After five years of searching, scientists finally found the species for the first time in the open sea—and an albatross nearly sabotaged the whole operation.

Along the coast of Baja California, Mexico in June 2024, scientists spotted a small group of ginkgo-toothed beaked whales swimming. This rare species was initially described in 1958, when a pair of Japanese scientists found one stranded on a beach near Tokyo. Since then, fewer than two dozen have been identified, always stranded on beaches.

The recent search began in 2020 when scientists started tracking a group of whales making a call not associated with any other species. The biologists named the call BW43 and returned to the area where they heard the call every year for three years. But each time, they lacked the specialized equipment that would ultimately help them find the ginkgo-toothed beaked whales.

When they returned last summer, they were aboard a research vessel with a collection of underwater microphones and high-powered binoculars. When a pair of beaked whales they had been following surfaced, they shot a small arrow that nicked a tiny piece of skin from one—which an albatross nearly stole before they could pull it aboard. Shouting and a few tossed bread rolls helped the crew chase off the bird long enough to pull in the sample and test its DNA, confirming they had, in fact, found the elusive ginkgo-toothed beaked whales.

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You’ve heard of the Death Star weapon in Star Wars, but have you heard of the carnivorous death ball sponge in the South Atlantic Ocean? The predatory sponge is one of 30 new species that scientists discovered on an expedition around Antarctica—and there are likely more new species to come. Scientists on board the Schmidt Ocean Institute’s research vessel Falkor (too) collected nearly 2,000 specimens from 14 different animal groups while looking for new species in the South Sandwich Islands. This group of volcanic islands sits in the South Atlantic Ocean about 1,000 miles east of the southern tip of South America and about 1,100 miles northeast of the Antarctic Peninsula.

So far, the scientists have evaluated less than 30% of the samples they collected. It will take time to examine and identify the rest, including whether they are an entirely new species or variations of known species. For example, they also collected “zombie worms,” from the genus Osedax, which researchers have seen before. These worms don’t have a mouth or gut. Instead, they secrete acid to “drill” into and absorb fats from animal bones, such as whale carcasses. Symbiotic bacteria living in the worms break down these fats, providing nutrients the worms can absorb.

The “death ball sponge” was found at 3,600 meters—more than two miles deep—at a trench near Montagu Island. Scientists are currently calling it Chondrocladia sp. nov. because it looks like some known species of the genus Chondrocladia, but the “sp. nov.” stands for “species nova,” or “new species.” Although it does not yet have a species name, researchers have concluded that it’s a predator, based on the tiny hooks that cover large white spheres on stalks extending from the sponge. Imagine multiple round lollipops sticking out from a sponge anchored to the ocean floor, except licking these lollipops would be like licking a cactus.

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So much of the ocean remains undiscovered because it is so difficult to reach, but the sea revealed more of its secrets in July 2017, when an iceberg nearly the size of Delaware broke away from a large ice shelf off the coast of Antarctica’s Weddell Sea. The slab of ice, about 2,239 square miles in size, separated from the Larsen C Ice Shelf in the Graham Land peninsula of Antarctica and left exposed a seabed previously hidden under 650 feet of ice.

Researchers sent a remotely operated vehicle named Lassie to explore the area in early 2019. When they discovered more than 1,000 dimples in the ocean floor, they were baffled at first. The dimples were not randomly scattered but were instead arranged in clear patterns. Some were shaped like a crescent, others like an oval, others in a line, and others in a sharp U-shape.

Scientists on board the research vessel debated what the dimples could be and added up the clues—their size, their shape, and knowledge of local sea life. They concluded the dimples were nests of yellowfin rockcod. Male yellowfin rockcod guard nests and their surrounding area for four months after females lay eggs, so the vast neighborhood of clustered nests likely enabled a network of guards to keep the eggs safe. Scientists suspect isolated nests on the outer edges were guarded by larger, stronger fish that could defend the area alone. About one in seven nests had pebbles in or around them, on which biologists think the fish laid their eggs to prevent rotting on the floor or predation from animals in the mud. Closer investigation also revealed that 72 of the 1,036 nests still contained larvae.

Discovery of this unexpected nursery area underneath an ice shelf supports the idea of establishing a protected area in the Weddell Sea to keep future generations of yellowfin rockcod safe.

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The ocean can be a dangerous place for juvenile fish, but researchers recently discovered a way some of them ward off predators—carrying around a baby. A baby anemone, that is. Divers off the coasts of Palm Beach, Florida and Tahiti have photographed evidence of a particular kind of symbiotic relationship between young fish and larval anemones. Symbiotic relationships are ones where at least one species benefits from the activity. In a mutualistic relationship, like this one, both benefit. In this case, the juvenile fish receives protection from becoming another fish’s dinner, and the anemone gets a free ride far beyond its birthplace.

Researchers used blackwater photography—a technique of taking photos in the open ocean at night—to snap pictures of filefish, driftfish, pomfrets, and a young jack swimming around with larval anemones in their mouths. Anemones are already part of a well-known mutualistic partnership with clownfish, which shelter in grown anemones, eat their leftover food scraps while keeping the anemones free of parasites, and circulate water around them. In this newly discovered relationship, the mutualism is short-term but has potentially long-term ramifications for anemone populations. Larval anemones can only travel so far on their own, but being carried further afield by fish means expanding their range.

The small fish, meanwhile, carry the anemone almost like a defensive shield; anemones pack a nasty sting that predators would likely want to avoid. The sting might not kill a fish that tries to take a bite, but it’s a far less tempting meal. The exciting discovery has now raised more questions for scientists to explore: How far and how long do the fish carry the anemone? Do they swap them out? How many anemones survive the trip? What exactly triggers fish to pick up anemones in the first place? Only further study may reveal some of these answers.

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For years, few scientists have devoted much time to studying Arctic diatoms, single-celled algae enclosed within a wall of glass-like silica. These bizarre organisms, after all, appeared frozen in the sea ice, stuck in dormancy, or so many scientists believed. In reality, however, ice diatoms are quite active—skating along the ice at temperatures as low 5ºF (-15ºC). That’s what scientists recently discovered when they collected diatoms from the Arctic during an expedition in the Chukchi Sea, the body of water that sits between Alaska and Siberia above the Bering Strait, and brought them back to their lab to study them.

Back at their lab, the researchers introduced the specimens to ice that resembled the diatoms’ natural environment. Then they watched as the diatoms sped along tiny channels in the ice. The algal cells glided along without the use of any appendages and without the kind of movement, such as wiggling, that other limbless organisms might use. The diatoms do it by secreting mucus that sticks to the icy surface at one end, creating a sort of anchored rope that they can pull themselves along. What stunned the researchers, though, was that the ice diatoms could move in this way at such cold temperatures. No other diatoms or other single-celled plants or animals had been documented as moving at temperatures this low.

Now the researchers are working to understand how diatoms function at such cold temperatures and, even more importantly, how they fit into the broader ecosystem of the Arctic. With the long-term existence of Arctic ice threatened by a warming global climate, researchers want to know: What will happen when the diatoms’ icy highways are gone?

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Dental offices and beauty salons follow strict hygiene and sanitation guidelines to prevent the spread of germs among people coming in for a teeth cleaning or eyebrow wax. But the same rules don’t apply to the “beauty salons” and mouth cleaning stations under the sea—and that may be a good thing.

Over 200 different species of fish and over 50 different shrimp species serve the vital role of cleaners to their fellow underwater residents. These cleaner fish often gather in “cleaning stations” on coral reefs where larger fish visit to have parasites and bacteria picked out of their mouths and off their scales. Scientists have known about this for many years, but only recently have they begun exploring what role these cleaning behaviors might play in moving microbes around the reef ecosystem.

To begin understanding this role better, researchers recently studied the impact of the cleaning goby. These fish are only about two inches long and often called neon gobies because their long, slender bodies have an iridescent stripe of color running from their nose to their tail. Scientists removed cleaner gobies from cleaning stations on two reefs off the coasts of Puerto Rico and St. Croix. Then they compared the water nutrients, microbe communities, and fish behavior of these reefs with nearby reefs that still had cleaning gobies. It turned out more fish visited the sites with cleaner gobies, and the variety of both microbes and nutrients differed between the sites.

Further research will help the scientists understand the significance of what they found to the broader health of marine environments, but one thing is clear: cleaner gobies do more than remove bacteria from individual fish. They play a big role in the microbe community of entire reef systems.

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Often, scientific research confirms what scientists already suspected, but other times, science reveals a twist that no one saw coming. That’s the kind of study that recently showed how much energy fish burn while hovering in place instead of resting on the ground.

Scientists have long thought that lingering motionless in the water is just as restful as it looks for fish. After all, most bony fish have a swim bladder—a sac of air that lets fish manage their buoyancy by inflating or deflating the bladder. When the bladder expands with gas, it makes the fish more buoyant. When fish deflate the bladder, they are less buoyant. So just hanging out in the water seems like it should be effortless.

The reality is a different story. Staying in place actually requires a lot of energy! Biologists from the University of California San Diego tested the energy cost of hovering versus resting on the bottom of a tank in 13 species of fish by measuring how much oxygen they used in each position. The researchers also measured each fish’s body size and shape and filmed them to observe their fin speed and movement. They used all these data to calculate each fish’s stability and found that remaining in place in the water column uses about twice as much energy as resting on the bottom. 

The scientists also learned that a fish’s shape and the placement of its pectoral fins (on either side of its body) affect how efficiently it can hover. The closer its pectoral fins are to the middle of the body, the less energy it uses to hover. Long, thin fish, like a halfbeak, are less efficient than more compact fish like damselfish and pufferfish. So if hovering uses so much energy, why do it? Staying still can help with guarding nests, feeding and other activities. It just doesn’t help with getting rest! 

The post When Hanging Out Takes Work appeared first on Marine Science Institute. The University of Texas at Austin..

Sometimes we consider a species rare because it truly is, whether because it’s endangered or simply because it naturally has sparse populations. But other times, a species may only appear rare because it lives in such remote locations that people haven’t managed to find it very often. That seems to be the case with the world’s largest amphipod, Alicella gigantea. Amphipods include more than 10,700 shrimp-like crustaceans found throughout the sea and other aquatic environments. And Alicella gigantea, which can grow to a little over 13 inches long, outsizes them all, but it lives in a very hard-to-reach habitat.

Alicella gigantea live on the deep sea floor, so it’s not surprising that researchers have not seen many of them. But a group of scientists from Western Australia wanted to find out just how rare—or common—these critters might be. They collected all the scientific records they could find for this species since the first specimen was discovered in 1899. They found 195 records from 75 locations throughout the world, including finds in the Pacific, Atlantic and Indian oceans. And it turns out, the large white crustaceans can live over quite a broad range of the deep sea, at depths ranging from 2.4 to 5.6 miles below the surface.

Knowing the conditions where the species lives, the researchers then estimated that similar habitat is present in more than half of the entire ocean floor—somewhere around 59% of it. Just as remarkably, when they analyzed the makeup of the specimens that had available genetic data, the scientists discovered that the Alicella gigantea amphipods were genetically very similar to one another from vastly different locations. That means huge swaths of the deep ocean floor throughout the world might be crawling with these huge crustaceans—making them not so rare after all.

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Sound travels farther in water than it does in the air, and acoustics are an important aspect of daily life for marine creatures ranging from whales to coral. In addition to communication, many marine animals rely on sound for navigation, hunting, avoiding predators, and choosing ideal places to live. Baby oysters are among the many species that depend on sound cues in their environment to determine where best to settle down. But researchers in Australia have discovered a growing challenge for oysters: the interference of human-created noise in the ocean.

To counter declining oyster populations, the researchers conducted a study in which they set up speakers to broadcast sounds that would attract larval oysters. The strategy was successful—the sounds did recruit larvae to settle down in those areas—but only in areas without substantial noise from shipping, machinery, and construction. In areas with higher levels of human noise pollution, the extra noise appeared to have drowned out the acoustic signals that the baby oysters rely on to determine a safe place to make their home.

But there’s good news: not only did the speaker strategy work in areas without man‑made noise pollution, but other strategies are also succeeding at building up oyster communities. In Chesapeake Bay, for example, oyster populations have shrunk to about 1% of what they once were. But officials have set up oyster sanctuaries where harvesting is banned. These sanctuaries have begun successfully restoring oyster populations—despite the simultaneous rise of two oyster parasites native to the area, the boring sponge and the mud blister worm. Neither of these parasites is dangerous to humans, and some evidence suggests that these oyster sanctuaries may even be helping the oysters become more resilient to parasites.

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