It's tiny, just a little bigger than a thumbnail. It's partially fluorescent. It's orange. And it's very poisonous.
Led by herpetologist Ivan Nunes, scientists have reported in the journal PLOS ONE the discovery of a new "pumpkin toadlet" species of the genus Brachycephalus. Found in the Mantiqueira mountain range along Brazil's Atlantic coast, it joins 35 other Brachycephalus species. The newcomer's official name is Brachycephalus rotenbergae, named after Brazilian conservationist Elise Laura K. Rotenberg.
Distinguishing one Brachycephalus species from another isn't straightforward, as there's no telltale identifying mark. Instead, a more holistic profile has to be developed to tell one species from another.
In this case, scientists considered the toad's genes, natural history, gross anatomy (including its skeletal structure), and even its songs. Brachycephalus toadlets emit what's considered an "advertisement call" — as in "Hey, I'm here!" — consisting of long sequences of chirps.
A find on the forest floor
The toadlet was studied on the forest floor in two areas.Credit: Nunes, et al. / PLOS ONE
Between October 2017 and September 2019, 76 field surveys were conducted in Brazil's Atlantic forests as researchers studied B. rotenbergae, whose turf is the forest floor in the São Francisco Xavier Government Protected Area. Among the new species' distinguishing features are a rounded snout and dark spots on its head. Additionally, it's a bit smaller than its similar-looking cousin B. ephippium, and its chirps are not quite like those of any other Brazilian pumpkin toadlet.
Glow-in-the-dark bones
Some of the toadlets' bones glow under UV lightCredit: Nunes, et al. / PLOS ONE
When B. rotenbergae is exposed to UV light, some of the bones just underneath their skin emit a green glow. "There's an idea," Nunes tells Smithsonian Magazine, "that fluorescence acts as signals for potential mates, to signal to rival males or some other biological role."
As for the brilliant orange color, it may be one of nature's warnings, a "don't eat me" signal of extreme toxicity. Indeed, other Brachycephalus toadlets have tetrodoxins in their skin, and the researchers suspect this toadlet does, too. (Pufferfish and blue-ringed octopi also carry tetrodoxins.) Ingestion of these neurotoxins can cause a number of progressively nasty things, from a pins-and-needles sensation to convulsions, heart attacks, and even death.
Currently, there is neither an indication that the species is endangered, nor is it especially rare. The only concern the researchers have for the species' survival is the growing population of wild boars in the area. The boars are tearing up the habitat of B. rotenbergae, rooting around for tasty seeds, nuts, acorns, and roots.
However, accidentally gobbling up a toadlet probably would be bad news for the boar.
Rabbits are, of course, adorable. We kvell over awww-inducing pictures of the little cuties who look like they couldn't hurt a fly. (Fun fact: Male rabbits are incredibly fierce when they fight each other and will actually fight to the death.)
Rabbits have been around for a long time, and they don't exhibit the same variations in size as for example, rodents. Even a big rabbit is not as big as, say, a capybara that can weigh from 60 to 200 pounds. Likewise, there is no rabbit anywhere near as tiny as a pigmy mouse of sub-Saharan Africa, which can weigh as little as 3 grams or as much as a zaftig 12 grams.
Researchers at Kyoto University's Primate Research Institute wondered why there are no horse-sized — or for that matter, tiny — lagomorphs. The lagomorph order includes rabbits, pikas, and hares.
The curious scientists recently published a paper titled "Why aren't rabbits and hares larger?" in the journal Evolution. It suggests the answer to this question may say something about the factors that most profoundly influence a species' evolution.
Size limited by competition
Credit: Victor Larracuente/Unsplash
First author Susumu Tomiya says, "The largest living wild lagomorphs weigh only about 5 kg on average, a tenth of the largest living rodent, the capybara."
There are breeds of domestic rabbits that can be somewhat large. Tomiya notes "some breeds of domestic rabbits and other extinct species can weigh up to 8 kg [about 17.63 pounds]. We were surprised by this, and so began to investigate what sort of external forces keep wild lagomorphs across the world from evolving larger body sizes."
After analyzing the available fossil record to explore how lagomorphs have fared through time, the team came to suspect that their size tended to be constrained by competition for food with larger herbivores.
Blame the sheep
As the researchers investigated the ecosystems in which lagomorphs lived, creatures of a different order, ungulates, came to their attention. Ungulates are an order of hoofed mammals including horses, rhinoceroses, and pigs. It also includes cloven-hoofed animals like cows and sheep.
It seems that ungulates were more than mere neighbors of rabbits, hares, and pikas. Similarly sized ungulates probably were their competitors.
The researchers calculated that large lagomorphs would require an excessive amount of energy — food, water and so on — to thrive, considerably more than smaller rabbits and hares. As a result, Tomiya says that when they compared "how much energy is used by populations of lagomorphs and ungulates relative to their body sizes," they found "that lagomorphs weighing more than six kilograms are energetically at a competitive disadvantage to ungulates of the same size."
To confirm their theory, the researchers next looked at the fossil record of North America. They found that the smallest hoofed animals predicted the size of the largest bunnies.
It remains true to this day, he says. "We see this pattern today across numerous eco-regions, suggesting that there is an evolutionary 'ceiling' placed on lagomorphs by their ungulate competitors."
The red queen versus the court jester
Tomiya says the study may help resolve biologists' ongoing "red queen" vs. "court jester" debate over the type of forces that most affect a species' evolution.
The red queen represents biotic forces and the court jester abiotic factors. ("Biotic" refers to other organisms that live in the same ecosystem as a species being studied, while "abiotic" refers to non-living factors such as climate, light, the quality of water, and so on.)
"For some time," says Tomiya, "the court jester model — ascribing diversity to abiotic forces such as the climate — has been dominant, due to the difficulty of studying biological interactions in the fossil record." He says the study's findings show that the red queen shouldn't be counted out when it comes to influencing evolution.
Life finds a way. That way may be uncomfortable, brimming with struggle, and demand an unsightly appendage or two, but as Jeff Goldblum reminds us, "Life will not be contained, life breaks free, it expands to new territories, and it crashes through barriers painfully, maybe even dangerously, but, uh, there it is."
To crash through those barriers, however, creatures must find the requirements for life waiting on the other side: namely, liquid water, a source of energy, and biogenic elements such as carbon and nitrogen. While terrestrial life has found some environments too hostile to call home, it's also evolved mind-boggling adaptations that allow it to access those three essentials in some bizarre places.
For example, the denizens of hydrothermal vents—such as the yeti crabs, scaly-foot gastropods, and Pompeii worms—dwell too deep in the ocean for sunlight to reach. Because their food chains can't rely on photosynthesis, they're supported by microbes that utilize a process called chemosynthesis, which converts chemicals from the vents into sugars and, in turn, useable energy.
Similarly, the Atacama Desert is a place so dry and barren that scientists compared it to the rusty dunes of Mars. Yet, even here, life has found a way in the form of microbes who wait patiently for those fleeting spits of rainfall to replicate.
And a new study, published in Frontiers in Marine Science, has proven Goldblum correct, uh, yes, once again. The study details the discovery of unusual creatures in one of the most unsympathetic environments on Earth's most inhospitable continent.
A cold dark place to call home
The Antarctic sessile creatures photographed on their home boulder.
Credit: Frontiers in Marine Science
Researchers made the discovery while drilling boreholes on the Filchner-Ronne Ice Shelf. Antarctica's ice shelves are giant, permanent floating ice sheets connected to the continent's coastlines, with the Filchner-Ronne shelf being one of the largest. Using a hot-water drill system, they bore through roughly 900 meters of the ice looking for sediment samples. Instead, they discovered a boulder. Two hundred sixty kilometers away from the ice front, the rock was nestled in a world of complete darkness at -2.2°C. And on it, they found sessile organisms.
"This discovery is one of those fortunate accidents that pushes ideas in a different direction and shows us that Antarctic marine life is incredibly special and amazingly adapted to a frozen world," Dr Huw Griffiths, the study's lead author and a biogeographer of the British Antarctic Survey, said in a press release.
Sessile creatures are defined by their inability to move freely. They live their lives anchored to a substrate—in this case, the aforementioned boulder. Common sessile animals found in coastal tide pools include mussels, barnacles, and sea anemones, yet none of these were present beneath the Antarctic shelf. Instead, the researchers discovered a stalked sponge, roughly a dozen non-stalked sponges, and 22 unidentifiable stalked organisms.
Previous boreholes had revealed creatures living in these murky waters, but they had always been free-moving predators and scavengers such as jellyfish and krill. It's not too surprising to find such animals under the ice shelves as their mobility allows them to seek out food that may drift beneath.
But sessile organisms depend on their food to be delivered to them. That's why they are so bountiful in tide pools; tides and currents are the DoorDash of the ocean world. It's also why the researchers found the sponge's Antarctic lodgings so astounding. Because they live 1,500 kilometers upstream from the nearest source of photosynthesis, it's unknown how a food supply reaches these sponges or whether they generate nutrients from some other means, such as glacial melt or carnivorous noshing.
"Our discovery raises so many more questions than it answers, such as how did they get there? What are they eating? How long have they been there? How common are these boulders covered in life? Are these the same species as we see outside the ice shelf or are they new species? And what would happen to these communities if the ice shelf collapsed?" Griffiths added.
To answer those questions, researchers will need to revisit the sponges to collect samples and study them in more depth. We'll also need to explore further the vast reaches of the Antarctic continental shelf. According to the release, counting the previous boreholes, scientists have only studied an area roughly the size of a tennis court to date.
Life will not be contained
As science discovers life in more and more unusual places, it's also considering more and more that life has not been contained to our pale blue dot. For example, the recent discovery of microbial life in the Atacama Desert has reignited hope that evidence of past life will be found on Mars. NASA's Perseverance Rover recently land on Mars to begin analyzing soil samples from the Jezero Crater to test that hypothesis.
Looking to the future, NASA's Dragonfly rotorcraft aims to explore the Saturn moon of Titan. The icy moon has a makeup similar to early Earth's, so the vehicle will study the moon's atmosphere and surface for signs of chemical evidence for life. And the ice-covered surface of Europa could hold twice as much water as Earth and a bevy of hydrothermal activity that could harbor life within our solar system.
Here life is, uh, and there it may be.
When it comes to senses like ours, tiny single-celled organisms floating in the ocean don't have much going on. And yet, as Sacha Coesel, the lead author of a new study from University of Washington researchers, puts it: "If you look in the ocean environment, all these different organisms have this day-night cycle. They are very in tune with each other, even as they get moved around. How do they know when it's day? How do they know when it's night?"
The answer, according to Coesel and her colleagues, is four previously unknown groups of photoreceptors that may help these organisms detect day, night, and each other.
Light and dark are vital to these organisms. When the sun is up, they become energized and grow. Cell division occurs at night when the darkness' ultraviolet wavelengths are less damaging to their DNA.
"Daylight is important for ocean organisms," says senior author Virginia Armbrust, "we know that, we take it for granted. But to see the rhythm of genetic activity during these four days, and the beautiful synchronicity, you realize just how powerful light is."
Photoreceptors and optogenetics
Credit: ktsdesign/Adobe Stock
Aside from being fascinating in their own right, these little "light switches" are likely to be of great interest to people working in optogenetics, a transformative area of scientific research.
This combination of optical technologies and genetics is giving researchers new insights into the workings of the brain, allowing them to, for example, turn on and off single neurons as they explore the brain's myriad pathways and interactions. Optogenetics also holds promise for better management of pain, and has cast new light on brain motor decision-making.
These new-found, naturally occurring photoreceptors may substitute for, or complement, human-made photoreceptors currently used in optogenetics. It's hoped that these newcomers will prove more sensitive and better equipped to respond to particular light wavelengths. Possibly because water filters out red light—the reason the ocean looks blue—the new photoreceptors are sensitive to blue and green wavelengths of light.
"This work dramatically expanded the number of photoreceptors — the different kinds of those on-off switches — that we know of," offers Armbrust.
Finding the new photoreceptors
Credit: Dror Shitrit/Simons Collaboration on Ocean Processes and Ecology/University of Washington
The researchers identified the previously undiscovered groups of photoreceptors by analyzing RNA they'd filtered from seawater samples taken far from shore. The samples were collected every four hours over the course of four days from the Northern Pacific Ocean near Hawaii. One set of samples was collected from currents running about 15 meters beneath the surface. A second set sampled deeper down, gathering water from between 120 and 150 meters, in the "twilight zone" where organisms get by with little sunlight.
Filtering the samples produced protists—single-celled organisms with a nucleus—measuring from 200 nanometers to one tenth of a millimeter across. Among these were light-activated algae as well as simple plankton that derive their energy from the organisms they consume.
Under-appreciated, tiny drivers of sea health
The new photoreceptors help fill in at least one of the blanks in our knowledge of the countless floating communities of microscopic creatures in our seas, communities that have a far greater impact on our planet than many people realize.
Says Coesel, "Just like rainforests generate oxygen and take up carbon dioxide, ocean organisms do the same thing in the world's oceans. People probably don't realize this, but these unicellular organisms are about as important as rainforests for our planet's functioning."
Usually, when scientists announce the discovery of a previously unknown animal, they have a specimen of the new arrival in hand. That's not the case, though, with Duobrachium sparksae, an amazing and beautiful ctenophore encountered 3,910 meters beneath the ocean surface about 40 kilometers off the coast of Puerto Rico. No one has met Duobrachium sparksae in person — we know of its existence only through several high-definition videos. ("Ctenophore" is pronounced teen-a-for, by the way.)
Says NOAA Fisheries' Marine Biologist Allen Collins in a NOAA press release, "It's unique because we were able to describe a new species based entirely on high-definition video."
It's also unique because it's such an exquisitely elegant organism.
Meet cute beneath the waves
The first encounter humanity had with the jelly occurred on April 10, 2015, when Deep Discoverer (a remotely operated vehicle or ROV) came across the gelatinous wonder. Fortunately, the ROV sports cameras that were sufficiently high-definition to clearly capture Duobrachium sparksae's fine details.
The animal was first noticed in a video feed by Mike Ford of the shoreside science team working in NOAA's Exploration Command Center far away, outside of Washington, D.C. The ROV was working the Arecibo amphitheater canyon. What Ford saw was, in his words, "a beautiful and unique organism."
Deep Discoverer's cameras produce externally high-resolution images, and are capable of measuring objects as small as a millimeter.The comb jelly's body is about 6 centimeters in size, and its tentacles are about 30 cm long.
While video-based animal identification can be controversial, there was little choice in this case. "We didn't have sample collection capabilities on the ROV at the time," says Collins. "Even if we had the equipment, there would have been very little time to process the animal because gelatinous animals don't preserve very well; ctenophores are even worse than jellyfish in this regard."
Artist's illustration
Credit: Nicholas Bezio/NOAA Office of Ocean Exploration and Research
Describing Duobrachium sparksae
All told, three individuals were observed by the scientists in three separate encounters with the ROV. The image at the top of this article is from the second encounter. The fact that three separate examples were easily spotted leaves scientists hopeful that the creature is not a rarity in the seas.
Ford describes what they saw:
"The ctenophore has long tentacles, and we observed some interesting movement. It moved like a hot air balloon attached to the seafloor on two lines, maintaining a specific altitude above the seafloor. Whether it's attached to the seabed, we're not sure. We did not observe direct attachment during the dive, but it seems like the organism touches the seafloor."
The role that Duobrachium sparksae plays in its ecosystem is not yet understood.
Finding a place in the family
The manner in which light refracted prismatically off the jelly's cilia combs immediately placed it in the ctenophore family as a start.
Collins explains, "We don't have the same microscopes as we would in a lab, but the video can give us enough information to understand the morphology in detail, such as the location of their reproductive parts and other aspects."
"We went," says Ford, "through the historical knowledge of ctenophores and it seemed clear this was a new species and genus as well. We then worked to place it in the tree of life properly."
The videos—the only "specimens" there are of Duobrachium sparksae—are now publicly accessible as part of the Smithsonian National Museum of Natural History Collection.
