This sea slug prefers turducken of the sea

You’re camping in the woods, about to tuck into some salmon you’ve caught when a bear appears. She’s waiting for you to eat your fish, so she can swoop in to eat you.

It’s a steal for the bear. For the price of a human, she’s bagged a human-salmon combo meal.

This scenario is hypothetical, but the feeding strategy it illustrates is not, according to a study published Nov. 1 in Biology Letters. In the report, a team of scientists from Britain and Italy termed the tactic “kleptopredation” and described it not in bears, but in a brilliantly colored sea slug, Cratena peregrina, that’s about the length of a soda can tab and commonly found in the Mediterranean.

These psychedelic slugs, also called nudibranchs, are known to feed on tentacled marine organisms known as hydroids, which are related to corals and sea anemones. They pop the polyps off the hydroids as one might pick a flower off a stalk. But based on lab experiments, the authors of the new paper suggest the slugs prefer to eat hydroids that have just ensnared plankton, a food item nudibranchs aren’t capable of capturing for themselves.

Think of it like wielding a living fishing rod. Or eating a turducken. Whichever your preferred analogy, kleptopredation — using one prey item to obtain another prey item — falls outside ecologists’ traditional classifications of feeding behavior. There’s predation, and there’s kleptoparasitism (when one animal takes food from another animal, like a pack of hyenas stealing a fresh kill from a lion). But kleptopredation is something new.

Patrick Krug, a nudibranch expert at the California State University, Los Angeles who was not involved in the study, said this “steal your meal, and eat you, too” strategy potentially rewrites how ecologists understand food chains.

Teaching bats to ‘speak’ in many dialects

Wild fruit bats, living in crowded roosts, are exposed to calls from hundreds of fellow bats from birth. Most often these calls are made in response to unsolicited physical contact and essentially amount to a crabby “move out of my way.” In a study published Nov. 1 in PLOS Biology, a team of Israeli researchers found that bat pups match their vocalizations to the group sounds they are immersed in, even if this “dialect” differs from that of their mothers.

Human babies and toddlers pick up the utterances around them effortlessly. The ability, called vocal learning, is considered critical for our spoken language.

But vocal learning has rarely been proved to exist in animals other than humans or songbirds, said Yossi Yovel, a neuroecologist at Tel Aviv University who led the study with graduate students Yosef Prat and Lindsay Azoulay.

In nonhuman mammals, much of the evidence for vocal learning “comes from animals that imitate human speech or other artificial sounds,” such as a zoo elephant emulating the Korean spoken by his keepers, Prat said. What he and his colleagues wanted to know was how an animal learns the sounds of its own species.

To start, the scientists captured 14 wild pregnant Egyptian fruit bats, a highly social and vocal species commonly found in the Middle East. Each mother gave birth in one of three chambers.

In these chambers, the researchers played different soundtracks to the pups continuously, starting from birth. The tracks sampled calls from actual bats, each mimicking a cave or tree roost with 300 bats in it, but featured different ranges of pitch.

For a few months, the bat mothers were also kept in the chambers and would regularly communicate with their offspring. But at 14 weeks, when a pup would normally become independent in the wild, the mothers were set free. At this point, the researchers started recording the pups’ vocalizations every few months until the bats reached adulthood.

Over time, the scientists found, the three pup groups took on distinct dialects.

Male mammoths more likely to die in ‘silly ways’

Swallowed by a sinkhole. Washed away by a mudflow. Drowned after falling through thin ice.

These are the fates that many unlucky mammoths suffered in Siberia thousands of years ago. Their well-preserved fossils have provided paleobiologists with insight into their prehistoric lives. Now, after performing a genetic analysis on the remains from the furry victims of natural traps, a team of scientists made a striking discovery: Most were male.

“In many species, males tend to do somewhat stupid things that end up getting them killed in silly ways, and it appears that may have been true for mammoths also,” said Love Dalen, an evolutionary biologist from the Swedish Museum of Natural History.

In a study published Nov. 2 in the journal Current Biology, he and his colleagues analyzed DNA from nearly 100 mammoth bones, teeth and tusks, and found that about two-thirds came from males. They speculate the reason for the skewed sex-ratio may have to do with the risky behavior that young males take after leaving the protection of their mothers to live on their own.

The finding was an accident, according to Patricia Pecnerova, a doctoral student at Stockholm University and lead author on the study. It came while she was entering data for a different project on mammoth genetics.

The biggest limitation in the study is that their explanation for the skew is speculative and based mostly on the behavior of present-day elephants. The thought is that mammoths, like today’s elephants, lived in matriarchal societies where adult females protected the young. But around the ages of 14 or 15 when puberty set in, males left their herd and either became loners or joined bachelor groups, which were often led by inexperienced males. That was when they were more likely to do something risky, and find themselves stuck in frozen muck.

Corals may have a taste for dangerous plastic

The ocean is full of plastic. Eight million tons are dumped in the seas every year. More than 200 species have been documented eating plastic, which looks colorful and edible but can kill them.

In lab experiments, even tiny corals, the organisms that make up reefs, have been observed nibbling on a confetti of broken down plastic fragments similar to what swirls through the depths. But they are not just eating whatever floats by. Instead, according to a new study in Marine Pollution Bulletin, some of the chemicals infused in the plastic may actually taste like food to the corals.

It is not yet clear how much plastic is consumed by corals in the wild, or what harm it might do to these important marine organisms, which are threatened by environmental dangers like warming seas and pollution. But understanding why plastic might appeal to them is important, especially because some particles appear to get stuck in the corals, potentially disrupting their digestive process.

Hundreds of chemicals are mixed into plastics to achieve certain textures or other characteristics. Because the corals sense the presence of food with receptors, it would not be all that surprising if some chemical additives mimicked substances that set off the corals’ appetites, suggested Alexander Seymour and Austin Allen, who were both graduate students at Duke University when they led this study.

Fossil offers European ancestor for giraffes

A near-perfect fossil unearthed close to Madrid appears to be an ancient European ancestor of giraffes, representing a new species in the family and one that had two sets of bony bumps on its head rather than the single set of modern giraffes.

Older fossils in the family known as giraffids have been found before, but none in such pristine condition, said Ari Grossman, an associate professor of anatomy at Midwestern University in Glendale, Arizona, who was not involved in the finding but said the whole field would benefit from it.

“It’s something most paleontologists dream of and very rarely find,” Grossman said. “The discovery in and of itself was breathtaking.”

Fossils of three other animals of the same species named Decennatherium rex by the researchers were also found, according to a new study in the journal PLOS One. They were not as complete, but all are about 9 million years old and provide evidence that ancestors in the giraffe family lived deep inside Europe much earlier than had been suspected. The fossils also suggest that there were physical differences between males and females.

“It fills a lot of gaps in what we knew about giraffes,” said Dr. María Ríos, the study’s lead author and a researcher with the Museo Nacional de Ciencias Naturales-CSIC in Madrid.

Everyone thinks of a giraffe’s long neck as its distinguishing feature. But its biological family members are defined by two characteristics unrelated to necks: they all have double-lobed canine teeth, and ossicones, the bony outcroppings on the top of their heads. Modern giraffes have two small to medium ossicones. The new species had a double set, with the back pair larger than the front.

Decennatherium rex looked more like a giant moose than either of its living family members, said Nikos Solounias, a giraffe evolution expert and professor of anatomy at the New York Institute of Technology, College of Osteopathic Medicine.

A humongous fungus and the genes that made it

Thousands of years ago, two microscopic spores spawned and created a monster. It grew — up to 3 feet a year — sending out dark, gnarly, threadlike organs called rhizomorphs that explored the subterranean darkness, foraging for food. Now it’s a nebulous body, a tangled mat beneath the Oregon soil that occupies an area the size of three Central Parks and may weigh as much as 5,000 African elephants.

Its scientific name is Armillaria ostoyae, but you can call it The Humongous Fungus. It’s the largest known terrestrial organism on the planet, according to the U.S. Forest Service. It’s also a deadly forest pathogen.

Although none (that we know of) are as big, there are many others in the Armillaria genus. These fungi cause root rot disease in plants in forests, parks, orchards and vineyards across North America, Europe and Asia. What sets them apart from other fungi is those stringy rhizomorphs that find weak trees, colonize their roots, kill and eat them.

An international group of scientists led by Hungarian researchers now have completed the first step to defeating these fungal demogorgons. In a genetic analysis published Oct. 30 in the journal Nature Ecology and Evolution, they uncovered tactics that help Armillaria develop their unusual rhizomorphs, grow so big and get so good at killing host plants.

The biologists compared the genomes of four Armillaria species to 22 related fungi and looked for unique or special proteins and gene families. They also compared the rhizomorphs to their fruiting bodies, called honey mushrooms, at different stages of development.

— New York Times News Service

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