With oceans covering about 70 percent of Earth’s surface, it’s hard to get
a sense of what’s happening across all that water at any given point in
time. Even with imagery from an extensive satellite network, making
sense of it all requires massive amounts of analysis. But that’s where
artificial intelligence (AI) can help. A recent AI analysis of 1.2 million
satellite images of the world’s oceans produced a surprising discovery
that wouldn’t have been possible without all that computing power.

Scientists from the University of South Florida and the National
Oceanic and Atmospheric Administration (NOAA) conducted the first
comprehensive global assessment of floating algae and found that
algal blooms are growing and spreading across the world’s oceans. They
looked at both “microalgal scum” and “macroalgal mats.” Microalgae is
made up of microscopic, single-celled organisms, and macroalgae refers
to seaweeds.

Both types of algae increased globally from 2003 to 2022, but
macroalgae far outpaced microalgae. While microalgae grew by about 1
percent per year, macroalgae expanded by more than 13 percent in the
tropical areas of the Atlantic and western Pacific oceans, with the biggest
increase occurring after 2008. Overall, macroalgal blooms covered about
43.8 million square kilometers (16.9 million square miles).

These huge, expanding carpets of seaweed have the potential to reshape
marine habitats. They can provide nursery grounds for marine species
and support fisheries, but excessive amounts of algae can deplete
oxygen, harm marine life, and release noxious compounds that may
affect people and animals. Scientists are investigating the causes of these
macroalgae blooms, including warming oceans and over-abundance of
nutrients and what it will mean for the future marine ecosystems.

The post A Seaweed Surge Sweeping the Seas appeared first on Marine Science Institute. The University of Texas at Austin..

Slugs may seem like dull creatures when hanging out in your garden, but the sea slugs that live in coral gardens are among the most colorful creatures in the ocean. More than 3,000 species of nudibranchs — marine sea slugs — exist, and scientists in Taiwan have just named a new one. While many nudibranchs are similar in size to their terrestrial cousins, the new one found in Taiwan is barely the size of a sesame seed. That makes it all the more remarkable that it was discovered by an undergraduate student on a recreational dive.

Ho-Yeung Chan was diving off the coast of Keelung in northern Taiwan when he discovered the tiny gastropod, just 3 mm long and translucent with black and yellow spots. Wondering what it was, he reached out to a nudibranch expert on Facebook. He learned his happenstance spotting was a new species, now named Thecacera sesama after the seed it resembles. Though he initially saw it in 2019, it’s taken several years to gather information about the creature due to Taiwan’s difficult weather patterns along the northern coast. Summers bring typhoons, and wintry monsoon seasons drop temperatures below 16 degrees Celsius with rough waves. Researchers therefore only get about four months a year to seek out the tiny animals.

What they have learned is that T. sesama lives a simple life. Living on bryozoans, small invertebrates commonly called “moss animals,” the nudibranch spends its days feeding, searching, mating, and laying eggs. Scientists suspect many more unidentified species of nudibranchs live in the region. They called the waters around Taiwan a “biodiversity hotspot for marine gastropods,” but it will take luck, persistence, and cooperative weather to discover what other wondrous marine slugs make these waters their home. 

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Nearly all animals with legs move mostly forward and backward to get around. But one marine creature tends to move a bit differently — crabs. Among more than 7,900 species of true crabs, which are those with four pairs of walking legs, a pair of claws and a tiny tail, the vast majority move sideways. A few other animals may move sideways, but true crabs are the only group where it’s the dominant form of locomotion. But what is especially unique about this adaptation is that it evolved just once, in a single ancestor about 200 million years ago.

To understand how remarkable that is, it helps to remember that evolution is random and disorganized, even as it’s responding to what helps a creature survive and reproduce in a particular environment. Mutations are always happening during reproduction. Most of these minor changes to genes have little effect, so they don’t alter a species’ evolution. Every so often, however, a mutation gives an organism an advantage over its peers. When that kind of mutation gives a creature a big enough survival or mating benefit, that individual and its descendants, who also have the same mutated gene, are more successful. Over generations, the mutated gene and the new trait it created gradually become a dominant feature of the species. As new species evolve from the species with the beneficial gene, they too carry the trait created by that gene.

Researchers from Japan watched how 50 species of true crabs move, and they combined their observations with existing data on the evolutionary relationships of true crabs from 344 species’ genes. They learned that the sideways locomotion evolved just one time during the early Jurassic period in an early ancestor of crabs. It likely gave crabs quite an edge in survival, letting them more quickly and easily escape predators during the Jurassic’s rapid expansion of marine habitats. Sometimes, it seems, one really happy accident is all it takes to change the course of a critter’s history and its gait.

The post Why Crabs Scuttle Sideways appeared first on Marine Science Institute. The University of Texas at Austin..

Few creatures under the sea may be as intelligent, creative, and yet still mysterious as octopuses. For example, scientists have known for nearly two decades that octopuses can use tools, which can be an indicator of higher animal intelligence. In 2009, researchers discovered that the veined octopus off the coast of Indonesia would collect and transport coconut shells across the ocean floor to construct shelters to hide in.

Since then, biologists have found that octopuses — even baby ones — are not above using other organisms for their purposes as well. Researchers in Portugal once recorded an instance of a species known as the seven-armed octopus hitching a ride on a jellyfish near the surface of the ocean off the coast of Terceira Island in the mid-Atlantic Ocean. And the octopus wasn’t a passive passenger either. It appeared to be using the jellyfish as protection, steering the jellyfish like an armored tank and directing the tentacles toward perceived threats, including the scuba divers watching it.

Another species of octopus has also been suspected of using jellyfish not only for defense, but even for offense. As far back as 1963, scientists observed a blanket octopus carrying around fragments of tentacles from the venomous Portuguese man-of-war. They hypothesized that the octopus used the tentacle pieces both to defend itself and as a weapon, and possibly even to capture food.

But not all octopus exploitation of jellyfish is necessarily so sinister. Argonaut octopuses, appropriately named for the famous mythological voyagers who journeyed with the Greek hero Jason on his quest for the Golden Fleece, have frequently been seen riding jellyfish. But argonaut octopuses aren’t picky. They have also been seen cruising along on plastic trash, leaves and other plant debris, and hitching a ride with animals besides jellyfish, such as crustaceans, fish, mollusks, and even other argonaut octopuses!

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More than two years ago, scientists found a mysterious “golden orb” two miles below the ocean’s surface in the Gulf of Alaska. Since then, they have been trying to figure out what it is. Could it be an egg of some sea creature? A species of sponge never seen before? Some other new organism? At last, they have an answer, but the discovery emphasized just how much people have to learn about the ocean’s depths.  

The golden orb was initially attached to a rocky outcropping at 2 miles deep. Researchers aboard a 2023 deep-sea expedition of the National Oceanic and Atmospheric Administration collected a sample using a remotely operated vehicle, but they were unable to identify it. They sent it to the Smithsonian National Museum of Natural History, where a team with expertise in genetics, deep sea biology, and animal structures worked to solve the puzzle.  

The object didn’t have normal animal anatomy, but its surface was covered in stinging cells called cnidocytes, commonly found on corals and anemones. Then one scientist recognized that the cnidocytes were a specific type called spirocysts. Spirocysts are only found in a class of corals and anemones called Hexacorallia, so the researchers compared the golden orb to another Hexacorallia specimen found in 2016. The spirocysts looked similar, but a genetic comparison could confirm that.  

Their first attempts to analyze the organism’s DNA did not reveal firm answers, probably because DNA from other organisms contaminated the sample. But further testing confirmed that the golden orb’s DNA was nearly identical to that of the 2016 Hexacorallia, a deep-sea anemone called Relicanthus daphneae. Scientists hadn’t recognized it because the orb was only part of the base of the anemone that attaches to rock. It took two and a half years and a team of scientists, but they solved the mystery of the golden orb at last. 

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Bull sharks have some of the highest levels of testosterone in the animal kingdom and a reputation for being among the most aggressive of all sharks. Until recently, scientists also thought they lived fairly solitary lives. In reality, though, bull sharks aren’t loners at all. They have surprisingly complex social networks, including “friends” they prefer and other sharks they avoid.

Researchers spent six years tracking 184 bull sharks in the Shark Reef Marine Reserve in Fiji, observing them for more than 136 hours during hundreds of dives. The sharks fell into three age groups: nearly-adults who were not yet sexually mature, sexually mature adults, and older adults who were past their reproductive age. The scientists considered sharks to be “associating” if they stayed within one body length of each other, and they identified several behaviors indicating different relationships. Some sharks swam side by side while others led or followed another shark or yielded to a passing shark. For example, two male sharks, named Big Poppa and Sharkbite, sometimes swam parallel to one another or engaged in a lead-follow behavior. 

Middle-aged adult sharks were the most socially connected, and they spent more time with sharks around the same size as they were. Older sharks generally got less social as they aged. Male and female sharks both spent more time with other females, yet males had slightly more overall social connections than females did. Much like humans, some bull sharks were social butterflies, while others had far fewer associations. Also like humans, some bull sharks intentionally avoided certain individuals. Since Fiji’s shark reserve is an ecotourism site, it’s unclear how much this social networking reflects bull shark behavior elsewhere or why it occurs. What is clear is that bull sharks have far more elaborate social lives than scientists ever realized.

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People use mirrors for grooming activities like shaving, washing their face, and applying makeup. Under the sea, though, hundreds of marine fish rely on cleaner wrasses to groom them. These little fish eat parasites and dead tissue from the skin of larger fish at “cleaning stations.” Now it turns out those cleaner fish understand how to use mirrors too, when given the opportunity! 

 A few years ago, scientists in Japan demonstrated that cleaner wrasses can recognize themselves in photos and mirrors. In those experiments, the fish did not attack photos showing their own face (even with their face edited onto an unfamiliar body), but they did attack photos of a cleaner wrasse that had an unfamiliar face—even when that face was photoshopped onto their own body. Those experiments also confirmed that the fish knew the photo was of themselves. When the photo included a mark on their throat that looked like a parasite, the fish tried to rub their throat to get rid of the parasite. They didn’t do that when shown an unfamiliar fish’s face having a parasite mark.

In a new study, the same scientists continued testing how cleaner wrasses interact with mirrors. They gave the fish a mark that looked like a parasite and then put a mirror in the tank. Within an hour, the fish used the mirror to find and rub off the fake parasite. But after several days with the mirror, they did something more surprising: the fish picked up a piece of shrimp from the tank floor and dropped it in front of the mirror, tracking its movement in the reflection as it fell to test how the mirror worked. This kind of behavior, which has been observed in manta rays and bottlenose dolphins, shows a level of self-awareness that people didn’t know cleaner wrasses had. It also suggests that many more animals have self-awareness than people realized!

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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.

The post When a Survival Strategy Backfires appeared first on Marine Science Institute. The University of Texas at Austin..

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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