Discoblog » The Wide (& Strange) World of Animals

That’s Not a Yawn. It’s a Scream Humans Can’t Hear.

Veronique Greenwood — Wed, 08 Feb 2012 17:54:41 +0000

The tarsiers of the Philippines are the smallest primates on the planet, at about five inches tall. They tend to keep their hind legs, which are twice as long as their bodies, folded up frog-style, except when leaping on their insect prey. And a tarsier eyeball, at just over half an inch wide, is as large as a tarsier brain.

But the weirdness doesn’t stop there. No, it most certainly does not.

Scientists had previously remarked that tarsiers were unusually quiet. And they also seemed to yawn quite a lot. Aww, cute, right? Sweepy wittle pwimates! But then, some scientists studying tarsiers made a startling discovery. Zoe Corbyn at New Scientist sums it up well: “Placing 35 wild animals in front of an ultrasound detector revealed that what [the scientists] assumed to be yawns were high-pitched screams beyond the range of human hearing.”

Turns out tarsiers are shrieking their brains out while their predators in the jungle, including birds and snakes, obliviously goes about their business. (And if you were already freaked out by them, as many YouTube commenters on the above video seem to be, we apologize for adding to the creepy.) It seems like a pretty handy, if eerie, ...

How to Turn a Cockroach into a Mobile, and Kind of Gross, Fuel Cell

Sarah Zhang — Mon, 06 Feb 2012 19:45:12 +0000

Discoid cockroaches, used in this study, can be up to 3 inches long.

From the digestive system that demolishes glue and toothpaste comes the first living, breathing, digesting cyborg-insect power source. Researchers have created a fuel cell that needs only sugar from the cockroach’s hemolymph (basically the cockroach version of blood) and oxygen from the air to make electric energy. The cell’s power density, 55 microwatts per square centimeter at 0.2V, is also very small compared to lithium batteries, so cockroach power wouldn’t be used as a mass power source. But these cyborg cockroaches could take sensors where no human wants to go: nuclear disaster sites, enemy military camps, inside the neighborhood Dumpster.

LiveScience lays out how electrodes inserted into the cockroach’s abdomen hijack its biochemical machinery:

The fuel cell consists of two electrodes; at one electrode, two enzymes break down a sugar, trehalose, which the cockroach produces from its food. The first of the two enzymes, trehalase, breaks down the trehalose into glucose, then the second enzyme converts the glucose into another product and releases the electrons. The electrons travel to the second electrode, where another enzyme delivers the electrons to oxygen in ...

The World’s Heaviest Insect Is 3,500 Times More Massive Than the Smallest Vertebrate

Veronique Greenwood — Wed, 01 Feb 2012 14:36:48 +0000

Record-breaking critters are always crawling, hopping, swimming or otherwise locomoting across our radar. To indulge our curiosity about two creatures who showed up recently in the news, we did a little quick and dirty Photoshopping. If you put the world’s heaviest insect—the giant weta, one of which was recently observed enjoying a carrot on a researcher’s palm—next to the world’s smallest vertebrate—a newly discovered frog so tiny it’s dwarfed by a dime—it might look something like this:

That’s the frog, off to the right. It weighs just 0.02 grams. This weta tipped the scales at 71 grams, according to Mark Moffett, the scientist who snapped her picture. So the cricket-like weta is about 3,500 times the weight of the frog, which Christopher Austin and colleagues found by scooping up leaf litter that was making a funny chirping noise and painstakingly removing the leaf fragments until they found a scrap that hopped.

Wetas can reach 10 centimeters in body length, 20 with their legs extended. The frog is about 7 millimeters long, so it would take around 30 of the frogs lined up head to tail to extend the length of ...

Naked Mole Rat Super Power #12: They Feel No Burn

Veronique Greenwood — Fri, 16 Dec 2011 20:35:23 +0000

Going for a squirm, snacking on poo, living the naked mole rat life.

Oh, naked mole rats, what fresh new weirdness do you have for us today? It wasn’t enough that you look like wee spring rolls with teeth, or that you are nearly blind and navigate your ramifying, oxygen-poor burrows by scent. No, you are also apparently immune to cancer, have terrible, gimpy sperm, and, we learn today, feel no pain from acid burns because your nervous system is defective.

We’d heard things like this before, naked mole rats.

We learned in 2008 that you were missing the gene that makes hot peppers painful, when scientists injected your paws with the stuff and you were blissfully unaware. Giving you the gene reversed that, but you still didn’t seem to care when acid was injected (did we mentioned that you’re also cold-blooded? Holy cow, mole rats.). Now, though, that team has figured out what’s going on in those neurons of yours, and it’s not what they thought.

They expected they’d find that you were missing the receptors for acids, nipping the pain message in the bud. But you had those, so they looked ...

Little Spiders Have Huge Brains That Spill Into Their Legs

Douglas Main — Wed, 14 Dec 2011 22:16:30 +0000

Tiny spiders have enormous brains, so big the neurons spill into their legs, causing the spiderlings of some species to bulge like overstuffed brain-bags (although the bump fades with adulthood). In some small arachnids this extended brain—really just a tangled mass of nerves—takes up almost 80 percent of the animal’s body cavity, and about a quarter the mass of its legs. Talk about thinking on your feet. The percentage of space devoted to cognition dwarfs that of humans, whose brains take up two to three percent of the body. It also trumps the setup of minute beetles and ants, whose brains make up only 15 percent of their weight. These insights come from a study published recently in the journal Arthropod Structure and Development, which set out to explain why small spiders are basically as adept as large spiders when it comes to completing relatively complex tasks like building webs. These massive distributed brains, it turns out, may be the answer.

The team’s findings basically conform to Haller’s rule, which holds that the brains of smaller animals are larger relative to their body size than those of big animals. The study ...

The Weird Wingless Ant That Glides About Backwards, Leading With Its Rump

Douglas Main — Tue, 13 Dec 2011 15:19:22 +0000

3D rendering of C. atratus guiding itself with its legs as it falls… backward.

Ants do well in rain forest canopies. Edward O. Wilson once catalogued 43 species of ants in a single Peruvian tree, which is “about equal to the entire ant fauna of the British isles.” But what if they fall? Ending up on the ground—far removed in distance and ecosystem niche—could be fatal. So hundreds of species of canopy-dwelling ants evolved the ability to direct their fall in a number of impressive ways, as a post in The Why Files explains. For example, the gliding ant Cephalotes atratus can:

Fly backwards, even though backward movement is rare among animals (house cats and hummingbirds being among the exceptions) Control their position with their hind legs, flipping backwards at first, then rotating in the last 3 to 5 milliseconds to smoothly land on its legs, its head pointed down Descend at about 75°, which looks like a controlled crash, but is sufficient to return the ants to the home tree Exceed the expectations of an ant-size nervous system by performing these presto-chango mental manipulations

Researcher Robert Dudley tells The Why Files that this type of “controlled aerial descent” evolved hundreds or thousands ...

Woolly Mammoth Cloned Within Five Years? We’ll Believe It When We Ride It

Douglas Main — Tue, 06 Dec 2011 22:33:47 +0000

Japan’s Kyodo News reports that Russian and Japanese scientists will start a project early next year to clone the woolly mammoth. The researchers also confirmed that a well-preserved mammoth thigh bone found in August contains remarkably well-preserved marrow cells.

The team, including researchers from a Siberian mammoth museum and Japan’s Kinki University, plan to extract an undamaged nucleus from the extinct animal’s bone marrow and insert it into the egg of an African elephant, a related animal; if all goes well the elephant could then give birth to a baby mammoth. The team has worked toward cloning the beast for more than a decade but until August, hadn’t found a sufficiently intact source of mammoth DNA (although they did create a copy of mammoth hemoglobin).

What could possibly go wrong? Assuming scientists can extract an undamaged nuclei from tissue that’s been frozen for more than 10,000 years, they then need to successfully insert it into an African elephant’s egg. This won’t be simple, considering that even procuring elephant ova is a challenge, said Japanese researcher Akira Iritani. And the cloning success rate for (non-extinct) animals like cattle is only 30 percent. The cloning technique Iritani plans to ...

Impostor Silverfish Rub up on Adolescent Ants to Create Their Smelly Disguises

Douglas Main — Mon, 05 Dec 2011 20:01:01 +0000

This silverfish didn’t fool the army ants. But many do.

The silverfish Malayatelura ponerophila is a kleptomaniac parasite that lives amongst the fierce army ants of southeast Asia, hanging out in the insect’s mobile colonies and living off the food they bring home. But how does it survive as a full-time impostor?

A study just accepted for publication in the journal BMC Evolution shows that these furtive freeloaders avoid detection by rubbing themselves all over immature ants called callows, “adolescent” ants which recently emerged from their larval stage. This gives the silverfish a coating of chemicals, called cuticular hydrocarbons (or CHCs), that the near-blind ants use to recognize nestmates in the dark. It is a dangerous way to live; army ants have keen senses and are usually adept at recognizing intruders, even expelling or killing fellow Leptogenys distinguenda if they smell like they’re from a different colony.

In the study, the researchers first catalogued all the cuticular hydrocarbons used by the ants, finding 70 in all. Doing the same for the silverfish, they found it made none of its own. They then coated the immature ants in a radio-labeled hydrocarbon similar in structure to others CHCs. They found that ...

Shrimp-Like Animals Spin Super-Sticky, Super-Strong Underwater Silk

Douglas Main — Mon, 21 Nov 2011 18:28:51 +0000

Scientists have discovered a new type of silk that combines the legendary stickiness of barnacles with the strength of spider silk (which is strong as steel and five times less dense). But the new material doesn’t come from a lab—it’s made by the small shrimp-like animal Crassicorophium bonellii. These crafty amphipods spin the silk using their legs like spiders to fashion mud-coated tubes in which they live.

In a study published this month in the journal Naturwissenschaften, researchers from the Oxford Silk Group found that the silk is extremely sticky and can cement underwater, like the glue used by barnacles to stick to virtually anything. But it’s also strong and flexible, with a solid fiber core like that seen in spider silk. Also like many spiders, the creatures process and excrete the material from ducts in their legs, which they then use to spin it and fashion themselves a home.

The material is first made in a gland similar to that of barnacles. The researchers think the similarities to spiders, both in the strength/flexibility of the fiber and spinning process with the legs, evolved independently, since C. bonellii are more closely related to barnacles than ...

The Latest on the Great Magnetic Cow Smackdown

Veronique Greenwood — Mon, 14 Nov 2011 18:09:07 +0000

“Magnetic Cows Are Visible From Space” is a memorable headline, and writers had occasion to use it several years ago, when, after poring over satellite pictures from Google Earth, a German research team reported that cows in the images reliably lined up along the magnetic field lines that run across the Earth. The magnetic field may be invisible to us without a compass (although we have sensors in our eyes that are theoretically capable of detecting it), but various animals, including sharks and turtles, are able to sense it, and one explanation for how birds manage to navigate on cross-continent migrations is that they are steering by the magnetic field. Are cows, too, endowed with magnetic field-sensing equipment?

That first paper, in 2008, and a follow-up in 2009, which showed that cows didn’t line up when they were near high-voltage powerlines (known to distort magnetic fields), seemed to indicate that they are. But an analysis of Google Earth images by another team finds no such lining up. In a back-and-forth over the last year in scientific journals, the first team reanalyzed the second’s data and said that ...

WWF Takes Drugged, Blindfolded Rhinos for an Aerial Joy Ride

Valerie Ross — Wed, 09 Nov 2011 19:31:17 +0000

Black rhinos are bulky, earthbound animals—but lately, the lumbering pachyderms have taken part in some pretty impressive aerial acrobatics. Nineteen of the endangered rhinos have taken thousand-mile trips across South Africa while dangling upside down from helicopters.

The WWF’s Black Rhino Range Expansion Project was moving the animals away from poachers and into larger, safer habitats. The safest, shortest mode of transport, in a region with bumpy roads and no jet-ready runways, turns out to be suspending tranquilized, blindfolded rhinos by the ankles from a chopper—Mafia-style. You can watch the rhinos flying through the air (and hear more about the project) in this video:

Next up: skydiving elephants?

[via New Scientist]

Image & video courtesy of Michael Raimondo / Green Renaissance & WWF

Buns of Prehistoric Steel May Have Graced the Backside of T. Rex, Sez Paleontologist

Veronique Greenwood — Wed, 09 Nov 2011 16:26:57 +0000

Like this, but with teensy arms and bigger teeth.

Instead of a loping, lunging Tyrannosaurus rex, imagine the thunder lizard doing more of a power-walk: the clenched bum, the stiff legs, the whole shebang.

Pretty evocative mental image, right? For that, you have a recent presentation at the Society of Vertebrate Paleontology meeting to thank. Dinosaur gaits are right up there with “how did flight evolve?” and “what makes us human?” on the list of fascinating, but intangible, things scientists wish we understood, and this particular scientist, Heinrich Mallison, a palaeontologist at the Museum of Natural History in Berlin, was leveling a criticism at traditional efforts to figure out how dinosaurs perambulated. Basically, he says that dinosaurs had such big butts that our usual method of comparing dinosaurs to small-cheeked modern animals is doomed to failure.

Dinosaurs, unfortunately, are not available for gait analysis today, and scientists have to depend on rare sets of tracks preserved in mud to study their movement. They usually assume that the faster a dinosaur is going, the longer their stride, which is how it works with modern animals, and most estimates find that dinosaurs, despite our sense of them as speedy ...

Stress Is a Real Killer—for Dragonflies

Douglas Main — Tue, 01 Nov 2011 14:25:24 +0000

Dragonflies can literally be scared to death of fish. Who knew? In a study published in November in the journal Ecology, researchers found that dragonfly larvae reared in the presence of fish were four times more likely to die before reaching adulthood, compared to larvae raised in an environment without predators. Similarly, 2.5 times more dragonflies croaked when raised in the same tank as an invertebrate predator. The larvae were kept in cages in full view of the predators, although the cages kept the predators from entering, and each one contained a small cup where the larvae could hide.

The study also found dragonfly nymphs raised in tanks with a fish were 10 percent more likely to die while metamorphosing into their winged adult form that we know so well. Apparently growing up is not only stressful for humans, and being constantly reminded of one’s mortality doesn’t help. (But of course, I’m anthropomorphizing their metamorphosizing.)

The researchers also measured body size in surviving larvae and adult dragonflies (a species called the dot-tailed whiteface, or Leucorrhinia intacta). They found no difference between the different groups, which came as a bit ...

Big-Hearted Maker-Folk Rush to the Aid of Homeless Hermit Crabs

Veronique Greenwood — Tue, 25 Oct 2011 15:42:00 +0000

So you finally got that 3D printer. It was pricey, but now you can fabricate anything you want! After making a few dozen hamster food dishes, a model of your own head, and as many toilet part replacements as you will ever (God willing) need, you’re feeling at loose ends. You need a cause to print for.

That cause, provided by Project Shellter at Makerbot, is wee little hermit crabs, who are, in turns out, suffering from a shell shortage. Wild crabs “are being forced to stick their butts into bottles, shotgun shells, and anything else they can find,” runs the manifesto-cum-blog post kicking off the project. “This is not acceptable.” 3D printing aficionados are instructed to post their designs for crab shells here. The Makerbot people will see what designs and materials their pet hermit crabs are most drawn to.

The idea, apparently, is to make shells that can be provided to captive crabs, not to fill the oceans with 3D-printed kipple in an attempt to alleviate the woes of their wild brethren (that, actually, was the quasi-serious goal of the last project we heard about that used ...

Scientist Definitively Proves Existence of Hyper-Intelligent Mythical Octopus

Douglas Main — Tue, 11 Oct 2011 18:16:42 +0000

Ichthyosaur bones: clear evidence of kraken lair

A well-known paleontologist found the lair of the heretofore-mythical kraken, proving that a hyper-intelligent giant squid hunted schoolbus-sized ichthyosauruses before breaking their necks, drowning them, and bringing them home to its pad on the bottom of the sea. After feasting on the delicious sea reptile, the kraken felt artistic and made a self-portrait, arranging their bones in a pattern resembling the suckers on its tentacle.

Unfortunately, this insane story isn’t a tale from a science-fiction novel. It was actually stated in a news release from the Geological Society of America and credulously regurgitated by many news sources covering it, taking the, uh, not entirely rock-solid claims made by Mount Holyoke College paleontologist Mark McMenamin at face value.

Ahem. Let’s be clear: there is absolutely no evidence for the existence of such a creature. It doesn’t even pass the most basic tests of common sense: where is the proof? There is none. But the coverage of the story would lead you to believe otherwise. Paleontologist-writer Brian Switek nails this point in his excellent write up from yesterday:

Extraordinary claims require extraordinary evidence. Esteemed scientist and science communicator Carl Sagan reminded us of ...

The Dumb Dog Food Aimed at Dogs. Maybe It’ll Work If They Have Dog TVs.

Douglas Main — Mon, 03 Oct 2011 21:41:49 +0000

“Beneful, please!”

The marketing geniuses at Nestle will air an ad targeted directly at dogs this week in Austria, featuring a high-pitched tone designed to appeal to canines, Reuters reports. The ad features the squeaking sounds of common dog toys as well as a high-frequency tone that is “barely audible to humans,” according to the news release. Noticeably absent from the release is the fact that all TV speakers are designed by humans for humans, with maximum frequencies reaching 20,000 hertz, the upper limit of human hearing. But most speakers top out well below this. While dogs can hear sounds up to at least 40 kHz, it’s almost impossible human speakers could broadcast any special tone that would be able to alert your dog any more than, say, a six-year-old.

But, giving “credit” where it’s due, the ad is clever, in a cynical-marketing-ploy way. “The television commercial aims to reach both the pet and the owner, supporting the special one-to-one relationship between them,” said Xavier Pérez, brand manager of Beneful for Nestlé Purina PetCare Europe. That special one-to-one relationship where Spot wags twice when he wants Beneful.

Image courtesy of Nestle

Dizzy Discus Throwers, Horny Beer-Bottle Beetles, and the Wasabi Alarm Clock: the 2011 Ig Nobels

Veronique Greenwood — Fri, 30 Sep 2011 16:07:20 +0000

Those classy folks at the Annals of Improbable Research are at it again. Last night, they announced the 2011 winners of some of the most coveted awards in science: the Ig Nobels.

You should watch last night’s ceremony in its entirety, but here are (drumroll) the winners:

First off, in Physiology…from the Cold-Blooded Cognition Lab at the University of Vienna, Anna Wilkinson, Natalie Sebanz, Isabella Mandle, and Ludwig Huber for their paper No Evidence of Contagious Yawning in the Red-Footed Tortoise, published this year in Current Zoology. As it turns out, if one tortoise is yawning, its buddies won’t join in. Not even if you show them movies of yawning tortoises. In Chemistry…Makoto Imai, Naoki Urushihata, Hideki Tanemura, Yukinobu Tajima, Hideaki Goto, Koichiro Mizoguchi and Junichi Murakami for determining what concentration of airborne wasabi can awaken sleeping people in case of emergency. They are the inventors of the wasabi alarm, described in US patent application 2010/0308995 A1. In Medicine…Mirjam Tuk, Debra Trampe and Luk Warlop, and Matthew Lewis, Peter Snyder and Robert Feldman, Robert Pietrzak, David Darby, and Paul Maruff for illuminating how an intense need to pee can affect your decision-making capabilities in their papers Inhibitory Spillover: ...

You Wouldn’t Like Your Fish When They’re Angry!

Douglas Main — Wed, 28 Sep 2011 13:19:13 +0000

Anger not your fish.

Your fish are probably pissed off if you keep them in a small aquarium, suggests a study published this month in the Journal of Applied Animal Welfare Science that looked at levels of aggression in the common aquarium species Midas cichlid (Amphilophus citrinellus). Fish stored in average-sized aquariums used by most small collectors (i.e. tanks holding fewer than 100 gallons) were significantly more aggressive and violent than fish in artificial stream environments or home in their natural habitat. With 180 million or so ornamental fish in America, that’s a lot of mad fish.

Though the results may sound like common sense—no animal likes being housed in cramped conditions—this is one of the first studies to concretely measure aggressive bouts, attacks, and other behaviors indicative of the creatures’ state of mind in aquariums of varying size and complexity. These bouts ranged from fin-flaring to nips and full-fledged bites. Similar studies have found that cramped sea urchins result to cannibalism, and that great white sharks, which are very difficult to maintain in captivity for long, tend to lash out at other sharks (especially the unfortunately named “soupfin”) when ...

Wall-Busting, Corrosive-Pooping, Garden-Eating Lizards Overrun Florida

Douglas Main — Tue, 20 Sep 2011 15:59:30 +0000

“You poop on the boat, you eat the garden, and I’ll wreck the wall.”

Florida has long had a big problem with introduced exotic species like the Burmese python, which can grow up to 23 feet long and has wreaked havoc on native wildlife. But in many ways lizards are even worse, accounting for 77 percent of the non-native reptile and amphibians species that have set up breeding populations in the state, according to a study published this month in the journal Zootaxa. Green and Mexican spiny-tailed iguanas are a particular nuisance. Besides competing with the 13 local varieties of lizard, they are famous for voraciously eating gardens, damaging boats and other property with their corrosive droppings, and even destroying concrete walls by burrowing beneath them.

The study found that people have introduced 137 foreign species of amphibians and reptiles into the state over the last 137 years, at an average of one per year. That gives Florida the dubious distinction of having the greatest number of established exotic amphibians or reptiles (“herpetofauna“) in the world.

The number of unwanted critters grew slowly but steadily (like a certain fabled herpetofauna) ...

Researchers Find Out How Pigeons Make the “Milk” They Barf Into the Mouths of Their Young

Douglas Main — Mon, 19 Sep 2011 22:10:15 +0000

Got (pigeon) milk?

Pigeons are known all-too-well by city-dwellers the world over. But what you might not know is that these birds produce a substance similar to milk for nourishing their young, and researchers have begun to understand how the critters do it. The pigeon version of “milk” is produced in fluid-filled cells within their crop, a specialized part of the esophagus typically used for storing food prior to digestion. Both male and female pigeons begin producing it about two days before their eggs hatch, and dutifully regurgitate the cottage cheese-like substance into their baby’s mouths for several weeks, after which they gradually introduce softened food to ready their young squabs for the real world.

A study published today in the journal BMC Genomics looks more closely at how pigeon milk is actually made. The researchers compared levels of gene expression between “lactating” and non-milk-producing cells, finding a high level of activation in genes involved with antioxidant synthesis and cell growth. This helps explain why their “milk” has high levels of antioxidants like carotenoids and is rich in fat, containing three times as much as cow’s milk. Wild-raised pigeon ...

The Original Suicide Bombers? Borneo’s Exploding Ants Commit Suicide to Protect Colony

Douglas Main — Wed, 14 Sep 2011 22:06:59 +0000

Borneo’s Camponotus cylindricus ants are a little touchy: if they encounter a foreign ant in their territory, they will latch onto its legs with their jaws and then quite literally blow themselves up, spraying a sticky yellow substance over the unlucky intruder. Not exactly the most level-headed reaction, but an effective one for defending the ant’s territory. A recent study in the journal Acta Zoologica describes how these volatile buggers release their noxious lather: by squeezing themselves to death with their abdominal muscles.

When it comes to “yellow goo”—the researcher’s actual technical term for the post-squish spritz—these ants are literally full of it. The reservoirs that house the liquid make up as much as half the volume of the ant’s body and stretch from the base of the head to the tip of the insect’s abdomen. The goo is made up of various irritating chemicals and strong adhesives that permanently bind the body of the dead Camponotus to the attacker. This enemy ant becomes subdued by the noxious chemicals, as well as the fact that it’s, well, forever glued to a corpse. After locking an enemy in a death grip, these ants bend and compress their abdomens so forcefully that the liquid violently ruptures out ...

Green, Glowing Kittens Contribute to HIV Research, Look Adorable

Veronique Greenwood — Mon, 12 Sep 2011 17:35:33 +0000

These wee green kittens not only glow, they’re resistant to the feline version of HIV.

Scientists exploring possible treatments for HIV have, purely as a byproduct of their methods, earned themselves a spot in today’s science blog postings: They’ve made glowing kittens.

When these green kitties were still twinkles in their parents’ eyes, scientists investigating a macaque gene thought to protect monkeys against feline immunodeficiency virus (FIV) inserted it into cat eggs with a lab-grown virus, intending to test whether cats carrying the gene were resistant to FIV as well. Researchers are interested in seeing how the macaque gene guards against FIV, which is the feline version of HIV, in hopes of transferring their insights to combating HIV.

But here’s where things get wacky: The team also included in the virus a jellyfish gene that makes a glowing green protein, to act as a signal. The virus does not always succeed in transferring the genes entrusted to it, but by including the jellyfish gene, the team gave themselves an easy way to tell when the transfer took place: kittens that glow green under fluorescent light, showing that they carry the jellyfish gene, almost certainly carry the macaque ...

Sneaky Toad Tadpoles Use Chemical Weapons Against Their Growing Competition

Joseph Castro — Fri, 02 Sep 2011 14:34:44 +0000

Think you’re a survivor? You’ve got nothing on the cane toad, former native of Central and South America, now scourge of Australia. To snuff out their competition for resources, cane toad tadpoles will actually cannibalize nearby cane toad eggs. And all those eggs the tadpoles are too full to gobble up? Well, researchers recently learned that the hardy amphibians have that covered, too: cane toad tadpoles release chemicals into the water that stunt the growth of developing embryos.

Scientists already knew that cane toads communicate with pheromones and use these chemical signals to locate tasty eggs. They also wondered if the pheromones have another, more insidious, purpose. Biologists at the University of Sydney set up a simple experiment to find out. They placed cane toad eggs in 20 containers filled partially with water; in 10 of those containers, they added tadpoles and separated them from the eggs with mesh screens.

The result: five days after hatching, the amphibians that developed with drooling tadpoles next door were 24 percent shorter and weighed 41 percent less than the isolated groups. Moreover, 40 percent fewer exposed tadpoles survived beyond 20 days, ...

Kinky Skinks Show That Size Matters in Speciation

Veronique Greenwood — Mon, 29 Aug 2011 17:05:30 +0000

When a male’s bits don’t fit with a female’s bits, you wind up with reproductive malfunction. But shape isn’t everything, as a team of researchers recently discovered while watching hundreds of skink lizards court and spark.

Most studies looking at how genitalia mismatch contributes to new species take the concept literally: if the bits don’t fit together like lock and key, matings will be unsuccessful. And if the mismatch between the gear of two groups is bad enough, they will form separate reproductive populations, and, eventually, species. But the idea, which was first tossed around more than 150 years ago, has been discounted as a possible source of new species. Differently sized or shaped genitalia is such a big change that it’s likely to come after many other speciation triggers, like mutations or long separations between populations divided by mountain ranges.

But, as this research team points out—and as anyone in the dating pool can tell you—there are other aspects of physical incompatibility that can have an effect on sex, and thus could get speciation started. If the mating posture, chemical cues, or timing are off, even having matching genitalia doesn’t mean a mating will work ...

Bad News for Roosters: If You Aren’t King of the Henhouse, Your Ejaculate Will Be Ejected

Veronique Greenwood — Fri, 26 Aug 2011 16:23:05 +0000

WHAT? Noooooooo!

If you haven’t heard about the corkscrew kookiness that is duck genitalia by now, you need to check that stuff out ASAP.

Ducks’ twisting vaginas and telescoping penises are well-known part of an evolutionary arms race between the sexes that’s been going on for millennia, with each side trying to exert control over which males’ sperm fertilize the female’s eggs—a battle that, especially in birds, is fierce, occasionally violent, and weird as all-get-out. The most recently discovered example of what biologists deem “sexual conflict,” a little behavior hens have developed called sperm ejection, upholds that fine tradition.

Hens, like many female birds, don’t always have a lot of control over who mates with them. Roosters tend to resort to “sexual coercion,” aka rape, and so a female might have any number of sexual partners that she didn’t get to choose. What’s a hen to do? Well, according to a new study in The American Naturalist, evolve a method for getting rid of sperm from males she didn’t particularly like, thus making sure her offspring are of the best quality.

Scientists had already noticed that hens tended to squirt out semen after some acts ...

Showy Male Birds—You Live Life Like a Candle in the Wind

Joseph Castro — Thu, 04 Aug 2011 19:59:19 +0000

For male Houbara bustards, extravagant sexual displays come with a price: rapid sexual aging. By studying over 1,700 North African Houbara bustards, researchers in France have learned that the birds, by age six, already begin producing smaller ejaculates with a large number of dead and abnormal sperm. The more showy the bustard, the quicker he burns himself out. As lead researcher Brian Preston said in a prepared statement:

This is the bird equivalent of the posers who strut their stuff in bars and nightclubs every weekend. If the bustard is anything to go by, these same guys will be reaching for their toupees sooner than they’d like.

[Read more about these peculiar birds and see a video of one of their seductive dances at the BBC.]

Image courtesy of Frank. Vassen / Flickr

Shrimp Couples Use Sponges as Gingerbread Houses

Joseph Castro — Mon, 01 Aug 2011 22:03:44 +0000

Up-close views of Typton carneus‘s shear-like tools.

In Hansel and Gretel, two ravenous children stumble upon a house made entirely of sugary goodness, and begin to chow down with abandon. But the kids’ journey quickly turns sour, as the owner of the house, a wicked witch, tries to cook them for dinner.

While the story seems to be a cautionary tale, it turns out that finding and living in an edible house can actually be pretty sweet—at least in the animal kingdom. Researchers in Prague have now learned that some tiny shrimp in the Belize Barrier Reef dine on fire sponges, their homes, by first tearing off pieces of tissue with claws not unlike those of Edward Scissorhands.

Scientists have long known that many species of invertebrates inhabit marine sponges. But in many cases, biologists have little insight on the relationship between host and squatter. Do shrimp and sponge benefit equally from the arrangement, or are the shrimp more like parasites, who take, take, take, and never give back? In the current study, published in the journal PLoS One, researchers decided to take a closer look at fire sponges and their ...

Extroverted Elephants Change Their Best Friends Over Time

Joseph Castro — Wed, 27 Jul 2011 20:41:26 +0000

While there are many different specific personality types, people are often categorized as either introverted or extroverted. Some like to keep to just a few close friends, rarely leaving their small comfort zones, while others are more outgoing, collecting friends wherever they go; most of us fall somewhere the middle. But we’re not the only mammals with this type of social diversity. Researchers in Sri Lanka have now found that many female Asian elephants—previously believed to be kind of antisocial—are social butterflies, changing their circle of friends as the seasons pass. Moreover, they maintain close ties with pals even after extended periods of separation.

In an Asian elephant society, females and calves stick together in groups of a few individuals, called herds, while males roam about more independently, doing male things. These small bands are part of much a larger group. In the new study, published in the journal BMC Ecology, researchers wanted to see how the relationships of individual female elephants changed over time, so they stalked nearly 300 pachyderms for five seasons in the Udawalawe National Park in Sri Lanka.

As expected, Shermin de Silva, a behavioral ecologist at the ...

Stealthy Whales Cut the Chit-Chat to Hide from Hungry Predators

Joseph Castro — Mon, 25 Jul 2011 20:46:03 +0000

To avoid enemy crafts, naval submarines will often run silently, shutting down nonessential functions and cutting crew chatter. Now, an international team of researchers has found that Blainsville’s beaked whales also go into stealth mode to avoid being eaten by their mortal enemies, orcas.

While they normally click, buzz, and whistle to one another in the deep, the aquatic mammals stop all gab when they enter waters shallower than about 550 feet, presumably because killer whales typically hunt in shallow water. This is surprising considering that the beaked whales spend only 40 percent of their lives in the deeper waters—scientists expected that the animals would need frequent communication to maintain social ties.

Makes you wonder: How often do the whales leave the deep to get away from all the gossiping?

[Read more at BBC.]

Image: NOAA

Studly Fish Aren’t Born, They’re Made—Sometimes Overnight

Joseph Castro — Mon, 18 Jul 2011 20:16:23 +0000

Some people like to say that men are always ready (and eager) for sex. Whether or not that’s true for humans, Stanford University researchers have recently learned that it is the case for certain male fish. Downtrodden male African cichlids, whose reproductive systems are so suppressed that biologists thought the fish couldn’t produce sperm, can successfully spawn within hours of rising to power, according to a new study published in the journal Proceedings of the Royal Society B.

Like many other animal species, a single leader—the biggest, baddest male—runs each group of African cichlids. This alpha male, which often sports vibrant blue scales, monopolizes the females and beats down other, weaker males in the community. (High school, anyone?) Because of this sexual exclusion, subordinate males suffer a noticeable pallor, decreased levels of reproductive hormones, and severely shrunken testes. Essentially, the fish trade sperm production for growth spurts, in hopes of someday overtaking the alpha male. Why waste energy making sperm if you can’t use it, right?

At least, that’s what lead author Jacqueline Kustan and her team thought. But when they took a closer look, they saw that the dominated cichlids generated no fewer sperm than the dominating ...