The World’s Smallest Vertebrate – A Tiny New Guinean Frog

Researchers from Louisiana State University have discovered the world’s new smallest vertebrate, a frog so small you could fit two on a dime end-to-end. From National Geographic:

The world’s smallest known vertebrate is a frog the size of a housefly, a new study says.

At an average of 7.7 millimeters long, the newfound Paedophryne amauensis is a hair smaller than the previous record holder, the Southeast Asian fishspecies Paedocypris progenetica, whose females measure about 7.9 millimeters…

It’s obvious “they’re adapting to fill a niche that nothing else is filling,” he said.

Indeed, the frogs likely evolved their tiny sizes to eat tiny invertebrates, such as mites, that are ignored by bigger predators, said study co-author Christopher Austin, a biologist at Louisiana State University in Baton Rouge…

Scientists locate the teensy animals by listening for their calls and trying to zero in on the sources of the sounds—no mean feat, since the high pitch of the calls make their sources especially hard for human hearing to locate.

Austin and graduate student Eric Rittmeyer tried four times to find the frogs before exasperatedly grabbing a big handful of leaf litter and putting it in a plastic bag.

The scientists then combed through the contents until “eventually we saw this tiny thing hop off one of the leaves,” Austin said.

The frogs are so small it’s hard to see their earth-colored skin patterns with the naked eye, so Austin took pictures and then zoomed in, using a digital camera like a microscope.

But photographing the amphibians was just as challenging as finding them. When Austin brought the camera to his eye, the subject would often already be gone.

The new frogs are “incredibly good jumpers—they can jump 30 times [longer] than their body size,” said Austin, whose study was published January 11 in the journal PLoS ONE.

That’s pretty incredible; there are some organisms that seem to straddle the boundaries between different worlds, and this is one of them. I want a report back from this frog on what life in the insect world is like. 

Photograph by Christopher Austin, via National Geographic

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Small Spiders’ Brains Fill Up Most of Their Body Cavity

If spiders weren’t creepy enough… It turns out that the smaller a spider is, the larger its brain is in proportion to its body size. This is how a tiny spider and a huge spider can have equally complex behaviour. What this means anatomically is that in some spiders, the central nervous system takes up as much as 80% of the body cavity, with their brains literally spilling into their legs. 

More from National Geographic:

Taking up so much body space for a brain would seem to be a problem for a spider’s other organs, Eberhard said. “But [that aspect] hasn’t really been studied.”

Just by the way the spiders look, though, it would make sense that the arachnids are trading something for their big brains.

For instance, in the jumping spider Phidippus clarus, which the researchers examined in a separate study, the adult’s digestive system is in the spider’s cephalothorax—its head and body cavity.

But “in the young one, all that stuff is filled up with brain,” and the baby spider has a less developed digestive system. It’s still unclear, though, what impact this has on the developing spiders…

Presumably, large brains are necessary to spin webs, a behavior thought to be more complex that, say, “a larval beetle that simply eats its way through the fungus where it lives,” Eberhard wrote in an article describing the research…

It’s a weird concept, having so much of a body filled up with the central nervous system (brain and spinal cord). I wonder how or if it relates to spiders’ reaction times, if their sensory organs (including skin) are so very close to their central nervous system. Is there a difference in reflexes between small and large spiders, or young and adult, attributable to relative brain size? Maybe we’ll find out in the future!

Bacteria-Farming Crab

Researchers have discovered that a certain species of crab apparently actively grows bacteria on its arms and eats them as its main source of food. From National Geographic

In 2006 scientists uncovered another species of yeti crab, K. puravida, living in cold, methane-seeping fissures about 3,300 feet (1,000 meters) deep near Costa Rica.

K. puravida regularly waved its claws slowly and rhythmically, puzzling scientists…

One early explanation for the behavior was that the crabs were trying to keep others at a distance.

But chemical analysis of K. puravida‘s tissues and the bacteria dwelling on its silky arms revealed the crustaceans dine mostly on these bacteria.

Video taken by submarine then revealed that the crabs harvest their crops using highly specialized hairy mouth appendages, which scrape the bacteria off their arms…

Researchers now suggest the claw-swaying helps wash nutrients over the bacteria, essentially fertilizing them…

It remains uncertain whether the yeti crab’s hairy appendages might help detect currents in the water. If so, the appendages may help crabs identify the sources of the nutrients that sustain their microbe “farms.” …

Deep-sea shrimp and other animals had been found with bacteria growing on them before, but this is the first clear evidence of a deep-sea animal farming its bacteria, said Thurber, whose study appeared November 30 in the journal PLoS ONE.

“This shows us how little we know about the deep sea, and how much more we might find and have to protect, as exploration for resources expands into these areas.”

That’s pretty fascinating behaviour; I wonder if this crab’s intelligence is unexpectedly high, or if this behaviour arose very accidentally and is now ingrained? It also reminds me of ants that farm aphids, an even more incredible behaviour in its resemblance to humans. These ants protect aphids and store aphid eggs, even taking aphid eggs with them when they start new colonies. They apparently stroke the aphids to “milk” honeydew out of them, which they then consume. And you thought we were the only farmers…

Anyway, as the last quoted paragraph states, this just reaffirms how much we have to learn about the deep sea and the natural world in general. It’s an exciting world out there!

Incredible Dinosaur Nest Photos

National Geographic has a slideshow of photos of the baby-dino-filled protoceratops nest uncovered recently, and they are unbelievable. Definitely not like anything I’ve ever seen.

To summarize from the slideshow, dinosaur child-rearing habits have been a bit of a mystery; it’s rare for animals to have a large number of offspring and stick around to care for them all, but this nest shows evidence of 15 young protoceratops, suggesting again that dinosaur families are not quite comparable to anything else we’re familiar with. These particular dinos may have all died simultaneously when buried during a sandstorm, since all of the fossils are pointing in a particular direction, presumably away from the wind. 

Photograph via Khishigjav Tsogtbaatar, Mongolian Academy of Sciences, via National Geographic

“Ten Weirdest Life-Forms of 2011”

National Geographic has a cool slideshow of the ten weirdest new life-forms seen in 2011, including a cyclops shark, tadpoles with fangs and the deepest-living animal found to date. And an ant with mind-controlling fungus growing out of its head, but I’m trying to block that one out.

We still have many, many species to discover out there – we only know a small fraction of them. Below is a table of the catalogued and predicted species on Earth and specifically in the ocean. The totals come out to 1/7th of Earth’s species having been catalogued so far, and less than 1/11th of ocean species, although those numbers are obviously subject to a lot of error.

Mora C, Tittensor DP, Adl S, Simpson AGB, Worm B, 2011 How Many Species Are There on Earth and in the Ocean? PLoS Biol 9(8): e1001127. doi:10.1371/journal.pbio.1001127, via Life Lines

We may have the cultural perception that the days of exploration are over, but they’re definitely not. There’s a lot more to discover out there, and there probably will be for generations. 

Giant Lake Discovered on Jupiter’s Moon Europa

From National Geographic:

Hidden inside the thick, icy crust of Jupiter’s moon Europa may be a giant saltwater body equal to the Great Lakes combined, NASA announced today.

Lying about 1.9 miles (3 kilometers) from the surface, the ice-trapped lake may represent the newest potentially habitable environment in the solar system—and one of the best prospects for the search for life beyond Earth.

“For decades scientists have thought Jupiter’s moon Europa was a likely place for life, but now we have specific, exciting regions on the icy moon to focus our future studies,” Don Blankenship, senior research scientist at the University of Texas at Austin’s Institute for Geophysics, told National Geographic News…

Similar in size to Earth’s moon, Europa is already thought to house a global, salty ocean beneath its 62-mile-thick (100-kilometer-thick) ice shell. NASA’s Galileo spacecraft, which orbited Jupiter and its moons from 1995 to 2003, first discovered evidence of the ocean…

There probably are many more lakes under Europa’s ice, Blankenship added.

Likewise, the prospects for searching for life on Europa could improve dramatically, as research suggests some of these icy lids covering the lakes may be much thinner than thought.

The techniques they used to infer the existence of the lake are the same that they use with satellite imagery of Earth, for example to discover subglacial lakes in Antarctica.

So when will we finally find out if there’s life on Europa? Uh… not any time soon, it seems. NASA planned a mission to specifically check out Europa using a probe called the Jupiter Icy Moons Orbiter (JIMO), but that plan was scrapped in 2005. This August, NASA launched a probe called Juno to investigate Jupiter; it will arrive around 2016. Taking more peeks at Europa does not seem to be in its job description, but who knows what it might see?

Fun facts: Juno will travel a total of 1.74 billion miles, or 2.8 billion kilometres. If that’s impossible to imagine, well, it should be. Meanwhile, the farthest probe from Earth is the Voyager 1, at 119 AU (an AU being the average distance from Earth to the sun), or almost 18 billion kilometres away. It was launched in 1977 and is still in communication with Earth. 

This news caught my attention because I was just reading about 2001: A Space Odyssey, and the sequels to that novel are based on there being life on Europa. What else did Arthur C. Clarke know that we don’t?

Life in the Mariana Trench

The Mariana Trench is the deepest part of the of the world’s oceans, at a maximum known depth of 10.9 kilometres. From Wikipedia: “If Mount Everest, the highest mountain on Earth at 8,850 metres (29,040 ft), was set in the deepest part of the Mariana Trench, there would be 2,060 metres (6,760 ft) of water left above it.” 

Most importantly, “At the bottom of the trench, where the plates meet, the water column above exerts a pressure of 1,086 bars (15,750 psi), over one thousand times the standard atmospheric pressure at sea level.” That, and the fact that light won’t reach that depth, means that life in the Trench (we’re buddies, I can call it “the Trench”) is very different from life as we know it near sea level, as well as difficult to observe. Yet observe it we have.

From LiveScience:

Gigantic amoebas have been found in the Mariana Trench, the deepest region on Earth.

During a July 2011 voyage to the Pacific Ocean chasm, researchers with Scripps Institution of Oceanography at UC San Diego and National Geographic engineers deployed untethered landers, called dropcams, equipped with digital video and lights to explore the largely mysterious region of the deep sea.

The team documented the deepest known existence of xenophyophores, single-celled animals exclusively found in deep-sea environments. Xenophyophores are noteworthy for their size, with individual cells often exceeding 4 inches (10 centimeters), their extreme abundance on the seafloor and their role as hosts for a variety of organisms.

For reference, the average human cell is about ~10 µm in diameter; that means these amoeba’s cells are 10,000 times the size of ours. That’s a big cell.

The researchers spotted the life forms at depths up to 6.6 miles (10,641 meters) within the Sirena Deep of the Mariana Trench…

Scientists say xenophyophores are the largest individual cells in existence. Recent studies indicate that by trapping particles from the water, xenophyophores can concentrate high levels of lead, uranium and mercury and are thus likely resistant to large doses of heavy metals. They also are well suited to a life of darkness, low temperature and high pressure in the deep sea…

The xenophyophores are just the tip of the deep-sea ecosystem iceberg. The expedition also found the deepest jellyfish observed to date, as well as other mysterious animals.

As I’ve said before, finding new species in novel environments like this is important – discoveries could have all kinds of applications. So little of the ocean has been explored that I’m sure there will be many, many discoveries to make in the future.

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