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Coleoid cephalopods, a group encompassing octopuses, squid and cuttlefish, are the most intelligent invertebrates: Octopuses can open jars, squid communicate with their own Morse code and cuttlefish start learning to identify prey when they’re just embryos. In fact, coleoids are the only “animal lineage that has really achieved behavioral sophistication” other than vertebrates, said Joshua Rosenthal, a senior scientist at the Marine Biological Laboratory in Woods Hole, Mass. This sophistication could be related to a quirk in how their genes work, according to new research from Dr. Rosenthal and Eli Eisenberg, a biophysicist at Tel Aviv University. In the journal Cell on Thursday, the scientists reported that octopuses, squid and cuttlefish make extensive use of RNA editing, a genetic process thought to have little functional significance in most other animals, to diversify proteins in their nervous system. And natural selection seems to have favored RNA editing in coleoids, even though it potentially slows the DNA-based evolution that typically helps organisms acquire beneficial adaptations over time. Conventional wisdom says that RNA acts as a messenger, passing instructions from DNA to protein builders in a cell. But sometimes, enzymes swap out some letters — the ACGU you might have learned about in school — in the RNA’s code for others. When that happens, modified RNA can create proteins that weren’t originally encoded in the DNA, allowing an organism to add new riffs to its base genetic blueprint. This RNA editing seemed to be happening more in coleoids, so Dr. Eisenberg, Dr. Rosenthal and Noa Liscovitch-Brauer, a postdoctoral scholar at Tel Aviv University, set out to quantify it by looking for disagreements in the DNA and RNA sequences of two octopus, one squid and one cuttlefish species. A common cuttlefish. The trade-off of heavy RNA editing is that it may slow DNA-based evolution. Credit…Roger Hanlon, Marine Biological Laboratory They found that coleoids have tens of thousands of so-called recoding sites, where RNA editing results in a protein different from what was initially encoded by DNA. When they applied the same methods to two less sophisticated mollusks — a nautilus and a sea slug — they found that RNA editing levels were orders of magnitude lower. Next, the researchers compared RNA recoding sites between the octopuses, squid and cuttlefish species and found that they shared tens of thousands of these sites to varying degrees. By comparison, humans and mice share only about 40 recoding sites, even though they are hundreds of millions of years closer in evolution than octopuses and squids. “Evolutionarily, that’s a big deal,” said Jin Billy Li, an assistant professor of genetics at Stanford, who was not involved in this study. The findings suggest that the editing sites are very important, he added.

Scientists reviewing video from camera traps watched dumbfounded as a 16-pound badger worked four days to bury a 50-pound calf carcass. Badgers, carnivores native to the American West, are generally nocturnal and spend most of their time in burrows. They are known to cache food to eat later — squirrels and rabbits, typically. No one has ever seen a badger put away such a large hunk of meat. The scientists had put out seven calf carcasses in an attempt to study scavenging behavior. At one site, the carcass had completely disappeared. A look at video from the camera trap was enough to see what had happened. After burying the carcass, the badger built a den next to his large food supply. No other badger visited the site. https://static01.nyt.com/science/gifs/badger.gif “It’s a substantial undertaking,” said Ethan H. Frehner, an associate instructor in biology at the University of Utah.

At the top, two flesh-toned siphons swish water over massive gills. At the bottom, a slimy, eyeless head resembles a mix of wet lips and diseased tonsils. In between, a glistening gunpowder blue body stretches up to four feet long. Instead of eating, bacteria in the creature’s gills helps it suck energy from sulfur. The whole thing is sheathed in a tusklike tube created from its secretions of calcium carbonate. Behold, the giant shipworm, your newest living nightmare. In a study published Monday in Proceedings of the National Academy of Science, Daniel Distel, a microbiologist at Northeastern University, and colleagues described a live one for first time. Its symbiotic relationship with bacteria provides clues to how the giant shipworm evolved its strange way of eating, and may enrich our understanding of infection in humans. “We were used to shipworms, which are very delicate creatures and much smaller,” said Dr. Distel, who spent two decades searching for a living specimen of this elongated clam. “This thing is a really beefy animal.” Giant shipworms live in a tusklike tube made of calcium carbonate.Credit…Marvin Altamia Dr. Distel tracked down living animals after a student spotted people sucking them down like spaghetti on YouTube. Local researchers and fishermen helped locate the creatures at the bottom of a remote lagoon in the Philippines, where they are a delicacy called tamilok purported to have medicinal properties. “It’s like finding the lost elephant graveyard or finding a dinosaur wandering around, live,” Dr. Distel said. Examining the shipworms wasn’t easy. Dr. Distel carefully cracked open its shell like a soft boiled egg, then slid the shipworm out and improvised a dissection. The shipworm’s small digestive system and gills were speckled with yellow, presumably from sulfur, suggesting that it lived off hydrogen sulfide, a toxic chemical, rather than the wood pulp diet of other shipworms. By analyzing the genomes of the shipworm along with its bacteria, as well as the enzymes it contained, Dr. Distel concluded that shipworms first ate wood, but acquired bacteria over millions of years of evolution that allowed it to mix an energy cocktail from chemicals in the seawater, mainly hydrogen sulfide from decaying wood, instead of eating the wood directly. A similar symbiotic relationship exists in a giant deep-sea mussel that is thought to have grown so big off energy from chemicals instead of organic matter. It’s kind of like how plants use sunlight, water and carbon dioxide in photosynthesis. This special relationship also has implications for medicine: “If you or I have bacteria living inside our cells, we’re sick,” Dr. Distel said. But either the bacteria evades the shipworm’s immune system, or the shipworm recognizes the bacteria as safe. “Understanding how an animal can live with bacteria inside their cells and not get sick and die could help inform our understanding of infection,” he added. Dr. Distel’s team believes many more mysteries may be unlocked by further study of this shipworm and its bacterial partner. “Whenever you find something so weird and so unusual, there’s often going to be unexpected discoveries that come from it,” he said.