Enlarge / A Day octopus ( Octopus cyanea ) named Scarlet parachutes her web over a coral head while Dr. Alex Schnell observes. (credit: National Geographic/Disney/Craig Parry)

With Earth Day fast approaching once again, it's time for another new documentary from National Geographic and Disney+: Secrets of the Octopus . It's the third in what has become a series, starting with the remarkable 2021 documentary Secrets of the Whales (narrated by Sigourney Weaver) and 2023's Secrets of the Elephants (Natalie Portman as narrator). James Cameron served as producer on all three.

Secrets of the Octopus is narrated by Paul Rudd. Per the official synopsis:

Octopuses are like aliens on Earth: three hearts, blue blood and the ability to squeeze through a space the size of their eyeballs. But there is so much more to these weird and wonderful animals. Intelligent enough to use tools or transform their bodies to mimic other animals and even communicate with different species, the secrets of the octopus are more extraordinary than we ever imagined.

Each of the three episodes focuses on a specific unique feature of these fascinating creatures: "Shapeshifters," "Masterminds," and "Social Networks." The animals were filmed in their natural habitats over 200 days and all that stunning footage is accompanied by thoughtful commentary by featured scientists.  One of those scientists is Dr. Alex Schnell ,  a native Australian and self described storytelling who has worked at Macquarie University, the University of Cambridge, and the Marine Biological Laboratory, among other institutions. Her research focuses on the intelligence of marine animals, particularly cuttlefish and octopuses.

We've been following the annual Dance Your PhD contest for several years now, delighting in the many creative approaches researchers have devised to adapt their doctoral theses into movement—from "nano-sponge" materials and superconductivity to the physics of atmospheric molecular clusters and the science of COVID-19. This year's winner is Weliton Menário Costa of the Australian National University for his thesis "Personality, Social Environment, and Maternal-level Effects: Insights from a Wild Kangaroo Population." His video entry, "Kangaroo Time," is having a bit of a viral moment, charming viewers with its catchy beat and colorful, quirky mix of dance styles and personalities—both human and kangaroo.

As we reported previously , the Dance Your PhD contest was established in 2008 by science journalist John Bohannon. It was previously sponsored by Science magazine and the American Association for the Advancement of Science (AAAS) and is now sponsored by the AI company Primer, where Bohannon is the director of science. Bohannon told Slate in 2011 that he came up with the idea while trying to figure out how to get a group of stressed-out PhD students in the middle of defending their theses to let off a little steam. So he put together a dance party at Austria's Institute of Molecular Biotechnology , including a contest for whichever candidate could best explain their thesis topics with interpretive dance.

The contest was such a hit that Bohannon started getting emails asking when the next would be—and Dance Your PhD has continued ever since. It's now in its 16th year. There are four broad categories: physics, chemistry, biology, and social science, with a fairly liberal interpretation of what topics fall under each. All category winners receive $750, while Costa, as the overall champion, will receive an additional $2,000.

Enlarge / A jackdaw tries to remember what color it was thinking of. (credit: Frans Buiter / 500px )

Humans tend to think that we are the most intelligent life-forms on Earth, and that we’re largely followed by our close relatives such as chimps and gorillas. But there are some areas of cognition in which homo sapiens and other primates are not unmatched. What other animal’s brain could possibly operate at a human’s level, at least when it comes to one function? Birds—again.

This is far from the first time that bird species such as corvids and parrots have shown that they can think like us in certain ways. Jackdaws are clever corvids that belong to the same family as crows and ravens. After putting a pair of them to the test, an international team of researchers saw that the birds’ working memory operates the same way as that of humans and higher primates. All of these species use what’s termed “attractor dynamics,” where they organize information into specific categories.

Unfortunately for them, that means they also make the same mistakes we do. "Jackdaws ( Corvus monedula ) have similar behavioral biases as humans; memories are less precise and more biased as memory demands increase,” the researchers said in a study recently published in Communications Biology.

Enlarge / Look at this very good boy taking a test to determine the origin of his spatial bias for a study on how dogs think. (credit: Eniko Kubinyi)

Research has shown that if you point at an object, a dog will interpret the gesture as a directional cue, unlike a human toddler, who will more likely focus on the object itself. It's called spatial bias, and a recent paper published in the journal Ethology offers potential explanations for why dogs interpret the gesture the way that they do. According to researchers at Eötvös Loránd University in Hungary, the phenomenon arises from a combination of how dogs see (visual acuity) and how they think, with "smarter" dog breeds prioritizing an object's appearance as much as its location. This suggests the smarter dogs' information processing is more similar to humans.

The authors wanted to investigate whether spatial bias in dogs is sensory or cognitive, or a combination of the two. "Very early on, children interpret the gesture as pointing to the object, while dogs take the pointing as a directional cue," said co-author Ivaylo Iotchev . "In other words, regardless of the intention of the person giving the cue, the meaning for children and dogs is different. This phenomenon has previously been observed in dogs using a variety of behavioral tests, ranging from simple associative learning to imitation, but it had never been studied per se."

Their experimental sample consisted of dogs used in a previous 2018 study plus dogs participating specifically in the new study, for a total of 82 dogs. The dominant breeds were border collies (19), vizslas (17), and whippets (6). Each animal was brought into a small empty room with their owner and one of the experimenters present. The experimenter stood 3 meters away from the dog and owner. There was a training period using different plastic plates to teach the dogs to associate either the presence or absence of an object, or its spatial location, with the presence or absence of food. Then they tested the dogs on a series of tasks.

Cats have a well-deserved reputation for being independent-minded and aloof, preferring to interact with humans on their own quirky terms. So you'd never see a cat playing fetch like a dog, right? Wrong. That sort of play behavior is more common than you might think—one of our cats was an avid fetcher in her younger years, although she's slowed down a bit with age. However, the evidence to date for specific fetching behaviors in cats is largely anecdotal.

That's why a team of British scientists set out to study this unusual feline play behavior more extensively, reporting their findings in a new paper published in the journal Scientific Reports. The researchers concluded that most cats who like to play fetch learned how to do so without any explicit training and that cats are generally in control when playing fetch with their humans. Specifically, cats will play fetch longer and retrieve the thrown object more times when they initiate the game rather than their owners. In other words, cats are still gonna be cats.

Many different animal species exhibit play behavior, according to the authors, and it's most common in mammals and birds. When cats play , their behavior tends to resemble hunting behavior commonly seen in European wildcats and lynxes: rapid approach and retreat, leaping, chasing, pouncing, and stalking. Initially, as kittens, they engage in more social forms of play with their littermates like wrestling, and they tend to engage in more solitary play as adults—the opposite of dogs, who usually start playing with objects alone before transitioning to social play.

Enlarge / "That's not my arm": Male serotine bats have such large penises, they can use them as an arm while mating. (credit: Alona Shulenko)

Little is known about the mating habits of the serotine bat ( Eptesicus serotinus ), but the males of the species boast unusually large penises—much larger than the vaginas of the females. The purpose of such an enormous organ has long baffled scientists. But a recent paper published in the journal Current Biology revealed that the males of this bat species use their gigantic members not for penetrating females while mating, but as an arm to push the female's tail sheath aside, thereby improving the odds of successful insemination.

Eurasian serotine bats can be recognized by their long smoky-brown fur (with pale yellow-brown underbelly), large triangular ears, and distinctive flight pattern: bouts of flapping interspersed with brief glides. They typically roost in older buildings like churches that have high gables and cavity walls, or abandoned mines. The male bats are largely solitary until fall mating season arrives, when they seek out females. Females set up maternity colonies around late May in Europe and remain there throughout the breeding season, usually giving birth to a single offspring (pup) in late summer.

Female bats have unusually long cervixes, the better to store sperm. The males have penises that are seven times longer than the females' vaginas, with a heart-shaped head seven times wider than the vaginal opening. “By chance, we had observed that these bats have disproportionately long penises, and we were always wondering, ‘How does that work?’” said co-author Nicolas Fasel of the University of Lausanne. “We thought maybe it's like in the dog where the penis engorges after penetration so that they are locked together, or alternatively maybe they just couldn't put it inside, but that type of copulation hasn’t been reported in mammals until now.”

Enlarge / Fish-eating kingfishers execute plunging dives into the water to capture prey, yet never seem to get concussed. (credit: Richard Towell)

There are many different species of kingfisher, and those that eat fish hunt by repeatedly diving head-first into the water when they spot tasty prey without suffering brain injuries like concussions. It turns out that diving kingfishers have several modified genes associated with diet and brain structure, according to a new paper published in the journal Communications Biology—notably mutations in genes related to the tau proteins that help stabilize neuron structure, although they can be harmful if too many build up.

“I learned a lot about tau proteins when I was the concussion manager of my son’s hockey team,” said co-author Shannon Hackett , associate curator of birds at the Field Museum. “I started to wonder, why don’t kingfishers die because their brains turn to mush? There’s gotta be something they're doing that protects them from the negative influences of repeatedly landing on their heads on the water’s surface.”

It's not the first time scientists have pondered this question, not just for kingfishers, but for other birds like gannets and woodpeckers . For instance, physicists at Virginia Tech studied diving gannets back in 2014 (publishing their conclusions in 2016 ), which fold their wings back as they dive, hitting the water with their whole body to snag underwater prey. From a physics standpoint, we're talking about an elastic body hitting the surface of water as fast as 55 MPH. The stress of moving from the medium of air to the much denser medium of water exerts a huge force on the bird's body, with an impact akin to tornadoes hitting the water. Yet despite the stress on their bodies, gannets (like the kingfisher) manage the feat again and again without injury, especially concussions.

Inspiration can come from the most unlikely places, as fantasy author Ursula Vernon , aka T. Kingfisher, clearly knows. Vernon won the 2023 Hugo Award for Best Novel this past weekend for her dark fairy tale, Nettle and Bone , and while she was unable to travel to Chengdu Worldcon in China for the event, she posted the text of her acceptance speech (read at the ceremony by a friend) on her Patreon. After the usual preliminary remarks and thanks, Vernon opted to forego "serious and heavy" commentary for the following revelation:

There is a species of water beetle that regularly gets swallowed whole by frogs. And while there’s a lot of things you can do to keep from being eaten, once you’re inside a frog, your options are severely limited. Generally you get digested. But this particular species of beetle said “You know, I bet there’s another way.” And it started walking. In fact, it walked through the frog’s digestive tract and out the back end.

This is 100 percent true, you can look it up.

Naturally, we did look it up and honestly can't believe we missed covering this fascinating study in 2020. (At least we didn't miss the 2022 study on how certain species of beetle have evolved unusual "back pockets" to safely house symbiotic bacteria during metamorphosis, shuffling the populations out of those pockets via friction to the genital area as they emerge from their pupae.)

Shinji Sugiura of Kobe University in Japan discovered the unusual survival strategy of the aquatic beetle Regimbartia attenuata while looking into how predation pressures can lead to the evolution of innovative escape behavior in prey animals. He fed a bunch of the beetles to a pond frog ( Pelophylax nigromaculatus ) under laboratory conditions, expecting the frog to spit the beetle out. That's what happened with Sugiura's prior experiments on bombardier beetles ( Pheropsophus jessoensis ), which spray toxic chemicals (described as an audible "chemical explosion") when they find themselves inside a toad's gut, inducing the toad to invert its own stomach and vomit them back out.