How many unborn brothers and sisters did this sand tiger shark devour to be here today? Photo by Amada44

Baby animals may seem irresistibly adorable, but in reality many of them are calculating killers. Hyena, wolf or even dog litter runts are pushed aside by their larger siblings and left to go hungry; fuzzy white egret chicks will kick their weaker clutch mates out of the nest to certain doom; and  baby golden eagles sometimes go so far as to snack on their smaller brothers and sisters while their mother looks on.

Perhaps most disturbing of all, however, is the case of the baby sand tiger shark. While sharks may not be the most snuggly animals to begin with, the sand tiger shark sets a new precedent for fratricide. This species practices a form of sibling-killing called intrauterine cannibalization. Yes, “intrauterine” refers to embryos in the uterus. Sand tiger sharks eat their brothers and sisters while still in the womb.

Even by nature’s cruel standards, scientists admit that this is an unusual mode of survival. When sand tiger sharks develop in their mother’s uteri (females have both a left and right uterus), some–usually the embryo that hatched first from its encapsulated, fertilized egg–inevitably grow faster and larger than others. Once the largest embryos cross a certain size threshold, the hungry babies turn to their smaller siblings as convenient meals. “The approximately 100 mm hatchling proceeds to attack, kill and eventually consume all of its younger siblings, achieving exponential growth over this period,” a team of researchers who investigated the phenomenon wrote this week in Biology Letters.  

Size differential between a recent hatchling (H) and an older embryo (E) from the same uterus in a typical litter the researchers samples. Photo by Chapman et al., Biology Letters

From what began as two uteri full of a dozen embryos results in just two dominating baby sand tiger sharks coming full term. What’s more, once the unborn babies consume all of the living embryos, they turn to their mother’s unfertilized eggs next, in a phenomenon called oophagy, or egg-eating. By the time those two surviving babies are finally ready to be introduced into the big, bright world, all of the pre-birth inner feasting has paid off. They emerge from their mother measuring in at about 95 to 125 centimeters long, or a bit longer than a baseball bat, meaning fewer predators can pick them off than if they had shared food with siblings and were smaller.   

This peculiar situation has implications for the genetic makeup of the species. Female sand tiger sharks, like many animals, mate with multiple males. Oftentimes in nature, females determine which males will sire the next generation by selectively choosing to mate with the most impressive bachelor (or bachelors) around. If mating with multiple males at any given time–as sharks, insects, dogs, cats and many other animals sometimes do–the babies that the female eventually produces share the same womb with siblings that may have different fathers. 

In this case, however, there are two modes of selection at work. Females may choose mates, but that does not guarantee those males’ genes will make the cut. The embryos the males sire will also have to survive the subsequent frenzy of cannibalism going on inside the female’s body. 

To find out whether some males are mating but missing out on actually producing offspring, the authors of this new study undertook microsatellite DNA profiling of 15 sand tiger shark mothers and their offspring. The researchers collected the sharks from accidental mortality events near protected beaches in South Africa between 2007 to 2012. By comparing the embryo genetics, the researchers could determine how many fathers were involved in fertilizing the eggs.

Nine of the females, or 60 percent, had mated with more than one male, the researchers found. When it came to which embryos hatched and grew large first (and thus would have survived if their mothers hadn’t have been killed), 60 percent shared the same father. This means that even if a female mates with more than one male, there is no guarantee that the male has been successful in passing on his genes. Rather, he could have just provided a convenient entree for another male’s offspring.

This also explains some male sand tiger shark behavior and physiology. Male sand tiger sharks often guard their mates against other males just after copulation. Males of this species also produce a conspicuously large amount of sperm compared to other sharks. Both of these characteristics increase the likelihood that the embryo fertilized by that male will successfully implant in the female’s uterus earlier, giving it a significant head start for developing more quickly than its siblings, which makes it more likely that the recent mate’s offspring will eat the others that may come along.

As for the females sand tiger sharks, some researchers think they actually may not have much of a choice when it comes to mating with multiple males.  It could be that females just give in to some amorous partners because the energetic cost of resisting those advances outweighs the cost of just conceding to the act–a behavior biologists call the convenience polyandry hypothesis. In this case, however, females may still get the final laugh since the males they first mated with and most likely preferred will have the greater chance of actually triumphing as the father of their children. “[Embryonic cannibalism] may allow female sand tigers to engage in convenience polyandry after mating with preferred males without actually investing in embryos from these superfluous copulations,” the researchers speculate.

While the females did invest in initially developing those doomed embryos, those investments are much smaller than what would be required to bring multiple embryos to full term. Those smaller embryos also represent resources allocated to the stronger, dominate embryonic winners, which thus have a better chance of surviving and passing on their mother’s genes than if she had spent the energy to instead birth multiple, weakling babies. In a way, the mother shark is providing nourishment for her strongest babies by producing multiple embryos that the most robust can eat. 

“This system highlights that competition and sexual selection can still occur after fertilization,” the authors write. For example, the first embryo to implant may not end up being the the one that survives the gladiator arena of the sharks uterus. While this new research still needs to delve into the details of the competition that takes place within the uterus, a picture is emerging based upon these initial findings: Females may chose which males to mate with or may be coerced into reluctantly mating, but male sperm fitness and the quality of the embryos they produce could also carry significant weight in which animals ultimately wind up as winners in this system. 

“This competition can play an important and probably under-appreciated role in determining male fitness,” the authors conclude. 

Flamingos depend on plant-derived chemical compounds to color their feathers, legs and beaks. Photo: Flickr user longhorndave

Pop quiz: Why are flamingos pink?

If you answered that it’s because of what they eat—namely shrimp—you’re right. But there’s more to the story than you might think.

Animals naturally synthesize a pigment called melanin, which determines the color of their eyes, fur (or feathers) and skin. Pigments are chemical compounds that create color in animals by absorbing certain wavelengths of light while reflecting others. Many animals can’t create pigments other than melanin on their own. Plant life, on the other hand, can produce a variety of them, and if a large quantity is ingested, those pigments can sometimes mask the melanin produced by the animal. Thus, some animals are often colored by the flowers, roots, seeds and fruits they consume

Flamingos are born with gray plumage. They get their rosy hue pink by ingesting a type of organic pigment called a carotenoid. They obtain this through their main food source, brine shrimp, which feast on microscopic algae that naturally produce carotenoids. Enzymes in the flamingos’ liver break down the compounds into pink and orange pigment molecules, which are then deposited into the birds’ feathers, legs and beaks. If flamingos didn’t feed on brine shrimp, their blushing plumage would eventually fade.

In captivity, the birds’ diets are supplemented with carotenoids such as beta-carotene and and canthaxanthin. Beta-carotene, responsible for the orange of carrots, pumpkins and sweet potatoes, is converted in the body to vitamin A. Canthaxanthin is responsible for the color of apples, peaches, strawberries and many flowers.

Shrimp can’t produce these compounds either, so they too depend on their diet to color their tiny bodies. Flamingos, though, are arguably the best-known examples of animals dyed by what they eat. What others species get pigment from their food? Here’s a quick list:

Northern cardinals and yellow goldfinches: When these birds consume berries from the dogwood tree, they metabolize carotenoids found inside the seeds of the fruit. The red, orange and yellow pigments contribute to the birds’ vibrant red and gold plumage, which would fade in intensity with each molt if cardinals were fed a carotenoid-free diet.

Salmon: Wild salmon consume small fish and crustaceans that feed on carotenoid-producing algae, accumulating enough of the chemical compounds to turn pink. Farmed salmon are fed color additives to achieve a deeper shades of red and pink.

Nudibranchs: These shell-less mollusks absorb the pigments of their food sources into their normally white bodies, reflecting the bright colors of sponges and cnidarians, which include jellyfish and corals.

Canaries: The birds’ normal diet doesn’t alter the color of its yellow feathers, but they can turn a deep orange if they regularly consume paprika, cayenne or red pepper. These spices each contain multiple carotenoids responsible for creating and red and yellow.

Ghost ants: There’s not much more than meets the eye with ghost ants: these tropical insects get their name from their transparent abdomens. Feed them water mixed with food coloring and watch their tiny, translucent lower halves fill up with brilliantly colored liquid.

Ghost ants sip sugar water with food coloring, which is visible in their transparent abdomens. Photo by Mohamed Babu/Solent News/Rex F/AP Images

Humans: Believe it or not, if a person eats large quantities of carrots, pumpkin or anything else with tons of carotenoids, his or her skin will turn yellow-orange. In fact, the help book Baby 411 includes this question and answer:

Q: My six-month-old started solids and now his skin is turning yellow. HELP!

A: You are what you eat! Babies are often first introduced to a series of yellow vegetables (carrots, squash, sweet potatoes). All these vegetables are rich in vitamin A (carotene). This vitamin has a pigment that can collect harmlessly on the skin, producing a condition called carotinemia.

How to tell that yellow-orange skin isn’t an indication of  jaundice? The National Institutes of Health explain that “If the whites of your eyes are not yellow, you may not have jaundice.”

Image via NASA/NOAA/GSFC/Suomi NPP/VIIRS/Norman Kuring

Last year, to celebrate the 42nd Earth Day, we took a look at 10 of the most surprising, disheartening, and exciting things we’d learned about our home planet in the previous year—a list that included discoveries about the role pesticides play in bee colony collapses, the various environmental stresses faced by the world’s oceans and the millions of unknown species are still out in the environment, waiting to be found.

This year, in time for Earth Day on Monday, we’ve done it again, putting together another list of 10 notable discoveries made by scientists since Earth Day 2012—a list that ranges from specific topics (a species of plant, a group of catfish) to broad (the core of planet Earth), and from the alarming (the consequences of climate change) to the awe-inspiring (Earth’s place in the universe).

Even the supposedly pristine Antarctic landscape is marred by trash heaps. Image via Germany Federal Environment Agency Report (PDF)

1. Trash is accumulating everywhere, even in Antarctica. As we’ve explored the most remote stretches of the planet, we’ve consistently left behind a trail of one supply in particular: garbage. Even in Antarctica, a February study found (PDF), abandoned field huts and piles of trash are mounting. Meanwhile, in the fall, a new research expedition went to study the Great Pacific Garbage Patch, counting nearly 70,000 pieces of garbage over the course of a month at sea.

2. Climate change could erode the ozone layer. Until recently, atmospheric scientists viewed climate change and the disintegration of the ozone layer as entirely distinct problems. Then, in July, Harvard researcher Jim Anderson (who won a Smithsonian Ingenuity Award for his work) led a team that published the troubling finding that the two might be linked. Some warm summer storms, they discovered, can pull moisture up into the stratosphere, an atmospheric layer 6 miles up. Through a chain of chemical reactions, this moisture can lead to the disintegration of ozone, which is crucial for protecting us from ultraviolet (UV) radiation. Climate change, unfortunately,  is projected to cause more of these sorts of storms.

3. This flower lives on exactly two cliffs in Spain. In September, Spanish scientists told us about one of the most astounding survival stories in the plant kingdom: Borderea chouardii, an extremely rare flowering plant that is found on only two adjacent cliffs in the Pyrenees. The species is believed to be a relic of the Tertiary Period, which ended more than 2 million years ago, and relies on several different local ant species to spread pollen between its two local populations.

4. Some catfish have learned to kill pigeons. In December, a group of French scientists revealed a phenomenon they’d carefully been observing over the previous year: a group of catfish in Southwestern France had learned how to leap onto shore, briefly strand themselves, and swim back into the water to consume their prey. With more than 2,000,000 Youtube views so far, this is clearly one of the year’s most widely enjoyed scientific discoveries.

5. Fracking for natural gas can trigger moderate earthquakes. Scientists have known for a while that whenever oil and gas are extracted from the ground at a large scale, seismic activity can be induced. Over the past few years, evidence has mounted that injecting water, sand and chemicals into bedrock to cause gas and oil to flow upward—a practice commonly known as fracking—can cause earthquakes by lubricating pre-existing faults in the ground. Initially, scientists found correlations between fracking sites and the number of small earthquakes in particular areas. Then, in March, other researchers found evidence that a medium-sized 2011 earthquake in Oklahoma(which registered a 5.7 on the moment magnitude scale) was likely caused by injecting wastewater into wells to extract oil.

6. Our planet’s inner core is more complicated than we thought. Despite decades of research, new data on the iron and nickel ball 3,100 miles beneath our feet continue to upset our assumptions about just how the earth’s core operates. A paper published last May showed that iron in the outer parts of the inner core is losing heat much more quickly than previously estimated, suggesting that it might hold more radioactive energy than we’d assumed, or that novel and unknown chemical interactions are occurring. Ideas for directly probing the core are widely regarded as pipe dreams, so our only options remains studying it from afar, largely by monitoring seismic waves.

The berries of Pollia condensata were found to produce the most intense color in the natural world. Image via PNAS

7. The world’s most intense natural color comes from an African fruit. When a team of researchers looked closely at the blue berries of Pollia condensata, a wild plant that grows in East Africa, they found something unexpected: it uses an uncommon structural coloration method to produce the most intense natural color ever measured. Instead of pigments, the fruit’s brilliant blue results from nanoscale-size cellulose strands layered in twisting shapes, which which interact with each other to scatter light in all directions.

8. Climate change will let ships cruise across the North Pole. Climate change is sure to create countless problems for many people around the world, but one specific group is likely to see a significant benefit from it: international shipping companies. A study published last month found that rising temperatures make it probable that during summertime, reinforced ice-breaking ships will be able to sail directly across the North Pole—an area currently covered by up to 65 feet of ice—by the year 2040. This dramatic shift will shorten shipping routes from North America and Europe to Asia.

9. One bacteria species conducts electricity. In October, a group of Danish researchers revealed that the seafloor mud of Aarhus’ harbor was coursing with electricity due to an unlikely source: mutlicellular bacteria that behave like tiny electrical cables. The organisms, the team found, built structures that traveled several centimeters down into the sediment and conduct measurable levels of electricity. The researchers speculate that this seemingly strange behavior is a byproduct of the way of the bacteria harvests energy from the nutrients buried in the soil.

Kepler 62f, discovered yesterday, is the most promising exoplanet candidate yet in terms of its potential to harbor life. Image via NASA/Ames/JPL-Caltech

10. Our Earth isn’t alone. Okay, this one might not technically be a discovery about Earth, but over the past year we have learned a tremendous amount about what our Earth isn’t: the only habitable planet in the visible universe. The pace of exoplanet detection has accelerated rapidly, with a total of 866 planets in other solar systems discovered so far. As our methods have become more refined, we’ve been able to detect smaller and smaller planets, and just yesterday, scientists finally discovered a pair of distant planets in the habitable zone of their stars that are relatively close in size to Earth, making it more likely than ever that we might have spied an alien planet that actually supports life.

The rare coealacanth’s genome is slowly evolving—and contrary to prior speculation, it probably isn’t the common ancestor of all land animals. Image via Wikimedia Commons/Amelia Guo

On December 23, 1938, South African Hendrick Goosen, the captain of the fishing trawler Nerine, found an unusual fish in his net after a day of fishing in the Indian Ocean off of East London. He showed the creature to  local museum curator Marjorie Courtenay-Latimer, who rinsed off a layer of slime and described it as “the most beautiful fish I had ever seen…five foot long, a pale mauvy blue with faint flecks of whitish spots; it had an iridescent silver-blue-green sheen all over. It was covered in hard scales, and it had four limb-like fins and a strange puppy dog tail.”

The duo, it turned out, had made one of the most significant biological discoveries of the 20th century. The fish was a coelacanth, a creature previously known only from fossilized specimens and believed to have gone extinct about 80 million years earlier. Moreover, its prehistoric appearance and unusual leg-like lobed fins immediately suggested to biologists that it could be an ancient ancestor of all land animals—one of the pivotal sea creatures that first crawled onto solid ground and eventually evolved into amphibians, reptiles, birds and mammals.

Now, though, the coelacanth’s full genome has been sequenced for the first time, and the results, published by an international team of researchers today in Nature, suggest otherwise. Genetic analysis suggests that the coelacanth doesn’t appear to be the most recent shared ancestor between sea and land animals—so its lobed fins didn’t make that first fateful step onto land after all.

When the researchers used what they found out about the coelacanth’s genome to build an evolutionary tree of marine and terrestrial animals (below), they found it’s more likely that ancestors of closely-related class of fish called lungfish played this crucial role. The ancestors of coelacanths and lungfish split off from each other before the latter group first colonized any land areas.

The genetic sequencing showed that terrestrial animals share a more recent common ancestor with lungfish, rather than coelacanths. Image via Nature/Amemiya et. al.

Additionally, the coelacanth’s prehistoric appearance has led to it commonly being considered a “living fossil”: a rare, unchanging biological time capsule of a bygone prehistoric era. But the genomic sequencing indicated that the fish species is actually still evolving—just very, very slowly—supporting the recent argument that it’s time to stop calling the fish and other seemingly prehistoric creatures “living fossils.”

“We found that the genes overall are evolving significantly slower than in every other fish and land vertebrate that we looked at,” Jessica Alföldi, a scientist at MIT and Harvard’s Broad Institute and a co-author, said in a press statement. Small segments of the fish’s DNA had previously been sequenced, but now, she said, “This is the first time that we’ve had a big enough gene set to really see that.”

The fact that the fish is evolving isn’t surprising—like all organisms, it lives in a changing world, with continuously fluctuating selection pressures that drive evolution. What’s surprising (though reflected by its seemingly-prehistoric appearance) is that it’s evolving so slowly, compared to a random sampling of other animals. According to the scientists’ analysis of 251 genes in the fish’s genome, it evolved with an average rate of 0.89 base-pair substitutions for any given site, compared to 1.09 for a chicken and 1.21 for a variety of mammals (base-pair substitution refers to the frequency with with DNA base-pairs—the building blocks of genes—are altered over time).

The research team speculates that the coelacanth’s extremely stable deep Indian Ocean environment and relative lack of predators might explain why it has undergone such slow evolutionary changes. Without new evolutionary pressures that might result from either of these factors, the coelacanth’s genome and outward appearance have only changed slightly in the roughly 400 million years since it first appeared on the planet.

Lashed to a spear made in the Gilbert Islands, researchers found a tooth from a dusky shark, a species previously unknown in the area. Image via PLOS ONE/Drew et. al.

For decades, a total of 124 swords, tridents and spears taken from the Pacific Ocean’s Gilbert Islands in the mid-1800s sat untouched in vaults in Chicago’s Field Museum. The weapons—each made up of dozens of individual shark teeth that islanders lashed to a wooden core with coconut fibers—were primarily considered artifacts of anthropological value.

Then, Joshua Drew, a marine conservation biologist at the museum, had an unusual idea: that the shark teeth lining the serrated blades could also serve as an ecological snapshot of the reefs that lined the islands more than a century ago. Sharks can be clearly identified solely by their teeth, so the teeth that islanders had harvested and used for their weapons might reflect historical biodiversity in the reefs that’s since been lost due to environmental degradation.

When Drew and others closely examined the hundreds of teeth on the weapons, they found that they came from eight different shark species, six of which were known to commonly swim in the Gilbert Islands’ waters. Two species, though—the dusky shark (Carcharhinus obscurus) and the spottail shark (Carcharhinus sorrah)—were something of a surprise. When the researchers looked at the scientific literature and various museum holdings of fish collected in the area, they found that these two species had never been documented within thousands of miles of the islands.

A trident lined with shark teeth, used in the study. Image via PLOS ONE/Drew et. al.

Drew calls this “shadow biodiversity”—a reflection of the life that lived in an ecosystem before we even started studying what was there. “[These are] hints and whispers of what these reefs used to be like,” he said in a press statement accompanying the paper documenting his team’s find, published today in PLOS ONE. “It’s our hope that by understanding how reefs used to look we’ll be able to come up with conservation strategies to return them to their former vivid splendor.”

Working with Mark Westneat, the museum’s curator of fishes, and Christopher Philipp, who manages the anthropology collections, Drew classified each tooth on every weapon by shark species, primarily using field guides and photos. In cases where the tooth’s identity was ambiguous, he made use of the Museum’s own ichthyological holdings, comparing it to preserved specimens from each shark species.

Because dusky and spottail shark teeth were found on the weapons—crafted sometime between the 1840s and 1860s, shortly before they were collected—the researchers believe these two species were once part of the ecosystem and have since been eradicated. There is the possibility that the teeth were harvested elsewhere and came to the Gilbert Islands via trade, but the team says it’s unlikely.

For one, sharks figure largely in the islanders’ traditional culture, and it’s well-known that they had effective shark-fishing techniques, making it unlikely that they’d go to the trouble of exporting teeth from afar. The two species’ teeth were among the most common found on the weapons, so it also stands to reason that they were fairly abundant nearby. Secondly, there is no historical or archaeological evidence that trade occurred between the extremely remote Gilbert Islands and either the Solomon Islands (the closest known location of spottail sharks) or Fiji (for dusky sharks).

It’s impossible to know for sure, but given the environmental degradation that’s occurred over the past century in the Pacific’s coral reefs, the researchers suspect that humans played a role in these sharks’ local eradication. Because sharks mature slowly and have a small number of offspring per individual, they can be wiped out quickly by moderate levels of fishing, and the commercial shark fishing industry started up in the area as early as 1910.

Rigorous fish surveys of the Pacific didn’t begin for a few more decades, so these weapons—and perhaps other human artifacts that incorporate biological specimens—serve as a valuable time capsule of the ecosystems that predated scientific study. Drew thinks that the “shadow diversity” we’ve since lost should inspire people in the marine conservation field to recreate the biodiversity that predates the Industrial Age.

“When we set up modern conservation plans, we shouldn’t sell ourselves short,” he told Nature last year, when he revealed his preliminary results at a conference. “We might not recapture the vivid splendor of those super-rich levels, but this information argues for setting up management plans to protect what sharks are there.”

Tadpole shrimp eggs can remain dormant for years, then burst into life when elusive desert rains arrive. Photo by Flickr user theloushe

As Easter draws near, we begin to notice signs of nature’s very own annual resurrection event. Warming weather begins “breeding lilacs out of the dead land,” as T.S. Elliot noted, and “stirring dull roots with spring rain.” Where a black and white wintery landscape just stood, now technicolor crocus buds peak through the earth and green shoots brighten up the azalea bushes.

Aside from this grand show of rebirth, however, nature offers several cases of even more overtly stunning resurrections. From frozen animals jumping back into action during spring thaws to life blooming from seemingly desolate desert sands, these creatures put a new spin on nature’s capacity for revival.

Resurrection fern

A resurrection fern, before and after watering. Photo by Flickr user Gardening in a Minute

As its name suggests, during a drought the resurrection fern shrivels up and appears dead, but with a little water the plant will burst back into vibrant life. It can morph from a crackled, desiccated brown into a lush, vibrant green in just 24 hours.

The fern doesn’t actually die, but it can lose up to 97 percent of its water content during an extreme dry spell. In comparison, other plants will usually crumble into dust if they lose more than 10 percent of their water content. Resurrection ferns achieve this feat by synthesizing proteins called dehydrins, which allow their cell walls to fold and reverse back to juicy fullness later.

Resurrection ferns are found as far north as New York and as far west as Texas. The ferns needs another plant to cling to in order to grow, and in the south it’s often found dramatically blanketing oak trees. A fallen oak branch covered in resurrection ferns are common features in southern gardens, though the ferns have also turned up in more uncanny locales: in 1997, astronauts took resurrection fern specimens onto the Space Shuttle Discovery to study how the plant resurrects in zero gravity. As investigators write (PDF), the fern “proved to be a hardy space traveler and exhibited regeneration patterns unaltered by its orbital adventure.” This earned it the title of “first fern in space.” 

Brine shrimp, clam shrimp and tadpole shrimp 

In the deserts of the western U.S., from seemingly life-barren rocks and sands, life blooms by just adding a little rain water. So-called ephemeral pools or “potholes” form tiny ecosystems ranging from just a few millimeters across to several meters deep. The ponds can reach up to 140 degrees Fahrenheit in the summer sun or drop below freezing during winter nights. They can evaporate nearly as quickly as they appeared, or linger on for days or weeks. As such, the animals that live there all have special adaptations for allowing them to thrive in these extreme conditions.

Ephemeral desert ponds in New Mexico. Photo: J. N. Stuart

Some of the potholes’ most captivating critters include brine shrimp (of sea monkey fame!), clam shrimp and tadpole shrimp. These crustaceans practice a peculiar form of drought tolerance: In a process known as cryptobiosis, they can lose up to 92 percent of their body water, then pop back into fully-functional action within an hour of a new rain’s arrival. To do this, the tiny animals keep their neural command center hydrated but use sugar molecules instead of water to keep the rest of their cells intact throughout the drought. Like resurrection ferns, brine shrimp, too, have been taken into space–they were successfully hatched even after being carried outside of the spacecraft. 

Most of these animals only live for about ten days, allowing them to complete their entire life cycle (hopefully) before their pool dries up. Their dried eggs are triggered to hatch not only when they’re hydrated again but also when oxygen content, temperature, salinity and other factors are just right. Some researchers, such as this zoologist quoted in a 1955 newspaper article, think that the eggs can remain dormant for several centuries and still hatch when conditions are right.

Wood frogs 

Some amphibians undergo their own sort of extreme hibernation in order to survive freezing winter temperatures. This suspended animation-like state allows them to slow down or stop their life processes–including breathing and heartbeat–just to the brink of death, but not quite. Wood frogs, for example, may encounter freezing conditions on the forest floor in winter. Their bodies may contain 50 to 60 percent ice, their breathing completely stops and their heartbeat is undetectable. They may stay like this for days, or even weeks. 

They achieve this through a specially evolved biological trick. When the frogs encounter the first signs of freezing, their bodies pull moisture away from its central organs, padding them in a layer of water which then turns into ice. Before it freezes, the frog also floods its circulatory system with sugar molecules, which act as an antifreeze. When conditions warm up again, they can make a complete recovery within a day, which researchers call “spontaneous resumption of function.” Here, Robert Krulwich explains the process: 

As seen through these examples, some creatures really do come back from the brink of death to thrive!

A model of a giant squid versus sperm whale. Photo taken at the American Museum of Natural History by Mike Goren from New York

For centuries, monsters of the deep sea captivated the imagination of the public and terrified explorers–none more so than the many-tentacled kraken. In 13th century Icelandic sagas, the Vikings wrote of a terrifying monster that “swallows both men and ships and whales and everything that it can reach.” Eighteenth century accounts from Europe describe arms emerging from the ocean that could pull down the mightiest ships, attached to bodies the size of floating islands.

Today, we’re fairly confident that a tentacled beast will not emerge from the depths to swallow up a cruise ship, but the enduring allure of such creatures lingers. None of the ocean’s massive animals, perhaps, are as intriguing as the giant squid.

Now, scientists have come one step closer to unraveling the mysteries behind this rare animal. As it turns out, contrary to some squid enthusiasts’ former hypothesis, all giant squid belong to a single species. What’s more, those animals are extremely similar genetically.

To arrive at these findings, researchers from the University of Copenhagen’s Natural History Museum of Denmark along with collaborators from 7 other countries genetically analyzed bits and pieces of 43 of the animals–which can grow more than 40 feet long and weigh nearly 2,000 pounds–recovered from all over the world.

Photo by Winkelmann et. al.

Their results indicated that, unlike most marine animals, giant squid harbor almost no genetic diversity. Remarkably, individuals as far apart as Florida and Japan, from a statistical standpoint, shared almost the same DNA. The giant squid’s genetic diversity turned out to be 44 times lower than the Humboldt squid, another large species, and seven times lower than the diversity of a population of oval squids living in a restricted area and thus prone to inbreeding. In fact, the giant squid’s diversity was lower than all other measured oceanic species, save the basking shark, which scientists believe recently underwent a severe population bottleneck in which most animals died and only a few individuals survived and repopulated the species.

The researchers can only speculate about this finding’s underlying reasons–the giant squid’s genetic data alone cannot provide a plausible explanation. Perhaps something about the giant squid makes it advantageous to cull mutations from its genome? Alternatively, the animals may have undergone a recent bottleneck, similar to what happened to the basking sharks, meaning that all giant squid following that event are closely related. Or perhaps a few foundered squid somehow wandered in new stretches of ocean, so when they populated these new habitats their offspring shared the same squid family tree. The short answer, however, is that the researchers simply do not know.

“We cannot offer a satisfactory explanation for the low diversity, and this requires future studies to resolve,” they write in a paper published this week in Proceedings of the Royal Society B.

This has been a big year for giant squid. In January, a Japanese team released the first footage of a giant squid interacting in its natural environment. Yet much still remains to be learned about these enigmatic creatures. For example, researchers still have no idea how large of a range the adult squid patrol, how long they live, how quickly they grow and whether problems such as climate change affect their populations.

For the imagination’s sake, however, perhaps it’s best if some mysteries endure.

“Despite our findings, I have no doubt that these myths and legends will continue to get today’s children to open their eyes up–so they will be just as big as the real giant squid is equipped with to navigate the depths,” said lead researcher Tom Gilbert in a statement. 

Fluorescent proteins all aglow in these corals. Photo by Michael Lesser and Charles Mazel, NOAA Ocean Explorer

Anyone who has gone scuba diving or snorkeling in a coral reef will likely never forget the dazzling colors and other-worldly shapes of these underwater communities. Home to some of the world’s most diverse wildlife hotspots, reefs are worth an annual $400 billion in tourist dollars and in the ecosystem services they provide, such as buffering shores from storms and providing habitat for fish that people eat.

Yet it’s a well known fact that coral reefs around the world are in decline thanks to pollution and rapidly warming oceans. However, determining just how reefs are faring–and designing steps to protect them–requires a way to accurately measure their health. Researchers tend to rely upon invasive, damaging techniques to figure out how corals are coping, or else they perform crude spot checks to determine reef health based on coral color alone.  But now, scientists have announced a new method of determining coral health that relies upon measuring the intensity of corals’ fluorescent glow.

Yes, glow. Corals naturally produce fluorescent proteins which glow an eery green when seen under a blue light–nearly all corals exhibit this physiological phenomenon.

“This is the first study to follow the dynamics of coral fluorescence and fluorescent protein levels during temperature stress, and shows that coral fluorescence could be utilized as a early indicator of coral stress,” said Melissa Roth, a marine biologist at the University of California, Berkeley (formerly of the Scripps Institution of Oceanography at the University of California, San Diego), in an email. “Because coral fluorescence can be measured non-invasively in the field, it could be an important tool for management of reefs,” she said. Roth and her colleague Dimitri Deheyn described their findings this week in Scientific Reports.

The degree to which a coral glows depends largely on another group of organisms, dinoflagellate algae. Corals are actually a symbiotic assembly of itself and these microscopic dinoflagellate algae–the dinoflagellates help corals attain nutrition, which in turn fuels the growth of coral reefs. The tiny organisms are also responsible for giving corals their typical brownish hue.

But dinoflagellates can abandon ship due to stressors such as increased temperature, a phenomenon known as coral bleaching. Left on their own without the aid of their dinoflagellate covering, the corals’ naturally white skin becomes glaringly visible. The coral can live for a little while after a dinoflagellate exodus, but not for long. If the algae do not return, the coral will die.

Knowing this, Roth and Deheyn decided to investigate how coral fluorescence might reflect the current state of a coral and its dinoflagellates’ relationship. They chose to use Acropora yongei, a common branching coral, in their experiments since it’s often one of the first corals shows signs of stress and bleaching in a reef. They subjected individual corals to one of two different experimental setups in their lab. In some containers, they pummeled corals with cold water, and in others they doused corals in hot water. Another group of corals served as a control. Then they let the corals pickle in their temperature-regulated waters for almost three weeks. 

The researchers found a distinct correlation between the degree of bleaching and the concentration of a coral’s fluorescent proteins, which in turn determined the strength of it’s glow. In the first 4 to 5 days, the fluorescent protein concentration and glow of both cold and heat-treated corals dropped. But by the end of the 20-day experiment, cold-stressed corals had acclimated and recovered to their normal level of fluorescence. Heat-stressed corals, on the other hand, bleached and began to glow even more strongly, probably because their dinoflagellate communities no longer blocked the coral’s underlying fluorescence. Like a supernova before a star’s final collapse, the corals send out a steady stream of intense glow just before their inevitable demise.

Corals pictures under white light (left panels) and blue light (right panels) show how corals subjected to heat stress eventually bleached and increased their fluorescent glow by the end of the experiment. Photo by Melissa Roth, Scientific Reports

After death, the glow stops. In a reef system, the bone white coral would gradually get masked by a film of green algae that coats the ruins of the now deceased organism.

Once corals start to bleach, conservationists or wildlife managers have few options for helping reefs as they begin to decline and often eventually die. But if they catch the problem ahead of time, they could try to help the coral with strategies such as shading with artificial structures or sediments, adding antioxidants to the water or introducing heartier dinoflagellates, though scientific studies validating these potential rescue methods are largely lacking. 

This new finding, Roth hopes, can be used to preempt reef collapse, serving as a sort of canary in the coal mine for corals in distress. “Managers could focus on the most sensitive corals on a reef, like branching corals, and look for rapid drops in fluorescence as an early sign of stress,” Roth said. This would give them about a week-long window to take action before full-blown bleaching began. “Bleaching would be like a heart attack,” she explained. “You would rather detect signs of high blood pressure or clogging of the arteries to address and avoid a heart attack.”

Managers who want to visualize their reef’s health can observe the glow by using a blue flashlight and a yellow filter over their snorkel mask, or they can film the phenomenon with a camera equipped with these same features. If managers notice the initial drop in coral glow that indicates an impending problem, for example, immediate action could perhaps be taken to try and rescue the reef.

“So the idea is that we can use coral fluorescence as a early indicator of coral health prior to bleaching, which could actually give time for managers to do something if they wanted to take actions to protect the reef. Obviously that may be difficult on a large scale,” she explained, adding that “as reefs become degraded the few that we have left might be protected more aggressively.”

Further research on how these findings might apply to other species of coral is needed, the authors write. They also hope that future studies will combine biology with engineering to help design a digital imaging system that better captures and quantifies the extent to which corals change their glow.

A study shows that wild perch are less fearful, eat faster and are more anti-social when exposed to a common pharmaceutical pollutant. Image via Bent Christensen

It’s obvious that anti-anxiety medicines and other types of mood-modifying drugs alter the behavior of humans—it’s what they’re designed to do. But their effects, it turns out, aren’t limited to our species.

Over the past decade, researchers have repeatedly discovered high levels of many drug molecules in lakes and streams near wastewater treatment plants, and found evidence that rainbow trout and other fish subjected to these levels could absorb dangerous amounts of the medications over time. Now, a study published today in Science finds a link between behavior-modifying drugs and the actual behavior of fish for the first time. A group of researchers from Umeå University in Sweden found that levels of the anti-anxiety drug oxazepam commonly found in Swedish streams cause wild perch to act differently, becoming more anti-social, eating faster and showing less fear of unknown parts of their environment.

The research group, led by ecologist Tomas Brodin, put wild perch in water with 1.8 micrograms of oxazepam diluted per liter—a level consistent with samples taken from surface waters near human development around Sweden. After 7 days swimming in the contaminated water, the perch had levels of the drug in their tissues that were similar to those of wild perch samples, indicating that the pharmaceutical was being absorbed into their bodies at rates similar to what’s happening in rivers and streams.

When they closely observed the behavior of these contaminated fish, the results were unmistakable. Those dosed with the anti-anxiety drug were more active, more willing to explore novel parts of their environment and more likely to swim away from the rest of their group as compared to fish that were kept in pristine waters. They also ate faster, finishing a set amount of plankton in a shorter time.

The researchers also included a third group of fish, exposed to levels of the drug way higher than those present in the environment. All of the changes shown in the fish exposed to the mild level of the drug were greatly exaggerated in this group, indicating that the drug was indeed responsible for the behavioral changes observed.

The idea of drug-addled fish might be funny, but the researchers say it could be a troubling sign of the way mounting levels of water-borne pharmaceuticals are affecting natural ecosystems. Because perch and other predator fish play a key role in food webs, altered foraging behavior—say, eating more prey—could lead to proliferation of the algae that their prey typically eat, upsetting an ecosystem’s balance as a whole. Or, if wild perch are engaging in more risky behavior (exploring parts of their environment they usually shy away from) it could lower the species’ survival rate.

Additionally, the research group worries that the drug could affect a broad spectrum of wildlife, because the particular receptor it binds to in the brain is widely distributed among aquatic species. And Oxazepam is far from the only drug that’s been found to pollute aquatic ecosystems—in the U.S., traces of over-the-counter painkillers, birth control hormones and illegal drugs have all been detected. “That environmentally relevant concentrations of a single benzodiazepine [oxazepam] affect fish behavior and feeding rate is alarming, considering the cocktail of different pharmaceutical products that are found in waters worldwide,” the researchers note in the paper.

These drug molecules can enter the environment in a few different ways. The practice of flushing old pills down the toilet is the first that probably comes to mind—and the easiest to prevent—but many pharmaceutical pollutants result from drug molecules that are ingested properly, go through the human body, pass out in urine and make it through wastewater treatment plants and into the environment. ”The solution to this problem isn’t to stop medicating people who are ill but to try to develop sewage treatment plants that can capture environmentally hazardous drugs,” Jerker Fick, one of the paper’s co-authors, said in a statement.

Two waved albatrosses, the only tropical albatross species, courting one another on the Galapagos Islands.
Photo by Flickr User James Preston

We often hear stories of animal love—tales of rare monogamy in the animal kingdom where life-long love is implied. But there is a distinction between romantic love and an efficient mating system. Here’s a look at some ocean animals to see what is really going on.

Albatrosses Get ‘Romantic’ to Increase Chick Survival

Albatross relationships seem especially relatable to humans. These long-lived and highly-endangered birds will court each other through ritual dances for years. Albatrosses are slow to reach sexual maturity, and some species even delay breeding for several years to learn specific mating rituals and to pick the perfect partner. The courtship behavior slows down once the pair bonds (an all too familiar aspect of human relationships). Once a pair is comfortable and breeding commences, they will return to each other and the same spot each year; for most albatross species, the bond lasts their entire life.

So is it love? The biological reality is that albatrosses only lay a single egg a year. With both parents fully invested in chick survival, their genetic heritage is most likely to survive. It may seem like love, but with those low reproduction rates no parents can afford to be deadbeats.

A waved albatross looks after its chick on the Galapagos Islands.
Photo by Flickr user James Preston

Seahorses Bond to Improve the Odds of Birth

If albatross relationships are reminiscent of fairytale romance, seahorses might be considered the swingers of the sea. Many seahorse species will bond with a mate, but that bond often lasts only through a single breeding season or until a more attractive female comes along. But, monogamy in this case is useful since it can be hard to find fellow seahorses due to poor swimming skills and low densities.

There is evidence that the longer that partners are together, the more successful at breeding they become and the two are able to produce more offspring per brood. One species of seahorse does appear to stick with a single mate for life: the Australian Hippocampus whitei. Practice makes perfect!

Two thorny seahorses (Hippocampus histrix), tails intertwined.
Photo by Bettina Balnis/Guylian Seahorses of the World 2010, Courtesy Project Seahorse

Two Angelfish Make a Strong Defense

Typically in pairs, French angelfish (Pomacanthus paru) help each other defend their territory against other fish. The couples have been observed spending extended periods of time together, exhibiting more of a monogamous social structure. Genetic monogamy (i.e. testing fertilized eggs to confirm they come from a single father) hasn’t been confirmed, but there have been observations of pairs traveling to the water’s surface to release their eggs and sperm together.

Monogamy is not that common in fishes, and it is mostly found in tropical and subtropical waters. Care needed from two parents, joint defense of territories, and difficulties in finding a mate all can play a role.

A pair of French angelfish off the coast of Brazil.
Photo by Barry Peters

A Permanent Glass Home for Shrimp

These intriguing glass sponges, called Venus’s flower-baskets (Eupectella aspergillum), are made of flexible silica that can better transmit light than our man-made fiber-optic cables. And many of these beautiful deep-sea sponges are also home to a monogamous pair of shrimp.

Several species of shrimp find refuge in these sponges, but due to the limited space found within the fine-mesh silica, only two adult shrimp can fit inside—and they are stuck there for life. The two spend their days cleaning the sponge and eating whatever bits of food manage to flow through. After they breed, their small offspring can squeeze through the holes in the mesh to escape, but eventually they will settle into a new home with their own imprisoned mate.

The  silica home of a male and female shrimp – the deep-sea sponge Venus’s flower-basket.
Photo via NOAA

The gift of this sponge, taken from the deep with the two dead shrimp still trapped inside, is considered good luck for couples marrying in Japan. It seems as though young human couples are not the only ones to share tight living spaces.

 Learn more about the ocean from the Smithsonian’s Ocean Portal. 

The Indian Peafowl may need help adapting to climate change. Photo by Sergiu Bacioiu

In the coming years, the birds of Asia’s Eastern Himalaya and Lower Mekong Basin, considered biodiversity hotspots by scientists, will need to relocate within the region to find viable habitat, according to a new study published in the journal Global Change Biology. The reason? Climate change. Researchers at England’s Durham University tested 500 different climate-change scenarios for each of 370 Asian bird species and found that every possible climatic outcome–even the least extreme–would have an adverse effect on the birds.

The researchers honed in on sensitive habitat in Bhutan, Laos, Cambodia, Vietnam and parts of Nepal and India, where development and population growth are occurring at a rapid clip and the effects of climate shifts are expected to be significant, with both wet and dry seasons intensifying. Portions of the region will suffer drastically, the study authors wrote, and certain climates will have “no present-day analogues” by 2100.

This will send birds in search of food. “Food availability [could become] more seasonal, meaning that in some periods there is an over-abundance of food, in others the birds starve,” lead author Robert Bagchi, formerly of Durham University and now a senior scientist at ETH Zürich, told Surprising Science. Species in the Lower Mekong Basin, which includes Laos, Cambodia and Vietnam, will be most vulnerable to these shifts.

In the most extreme cases, the research showed, birds will need to be physically relocated–an outcome scientists are hoping to avoid. Instead, they’re recommending proactive conservation. “Maintaining forest patches and corridors through agricultural landscapes is likely to be a far more effective and affordable long term solution than translocation,” Bagchi said. Linking bird habitat will be key so that species can move between sites that are currently viable and those that will suit them in the future.

The ramifications of bird relocation on plants and other animals has yet to be examined, but the shifts likely won’t bode well. Plant species that rely on birds to disperse seeds may not be able to survive, according to Bagchi. “Understanding how species interactions are going to change is very much at the cutting edge of what ecologists are trying to understand at the moment,” he said.

The study joins a growing body of research into how changes in climate affect food and water supplies, ranges, breeding habits and life cycles for birds and a variety of wildlife. Among those studied and deemed at risk are California’s threatened and endangered bird species. Research published last year showed that sea-level rise and changes in precipitation will most seriously imperil wetlands birds.

Investigators with the National Science Foundation are currently studying the prospects of Antarctica’s Adélie penguins for surviving climate change; the birds rely on floating sea ice, and if warmer temperatures melt that ice, the penguins will vanish. The top swimmers and foragers among their ranks have the best chances of survival, according to researchers, whose work is detailed in this video.

Scientists in Antarctica are studying how climate change is affecting Adélie penguins. Photo by Penguinscience.com

Among mammals, the adverse impacts of global warming on polar bear habitat has been well documented. A 2011 study showed the bears must swim longer distances in search of stable sea ice and that cubs are 27 percent more likely to die as a result of the extended plunges. New research published in the journal Ecology reveals that elephants are also vulnerable: Higher temperatures and lower precipitation have created an acute threat to Myanmar’s endangered Asian elephants, particularly babies.

Land-dwelling North American animals have also been affected. The snowmelt required by wolverines for reproduction is so greatly diminished that federal wildlife officials nominated the animal for Endangered Species Act listing earlier this month. And climate-change-induced, late-spring snowfalls have caused the Columbian ground squirrel to extend its Rocky Mountains hibernation by ten days over the past 20 years, according to Canadian researchers. By emerging later, the animals lose valuable time to stock up on the food they need to survive the next winter.

Conversely, another hibernator, the yellow-bellied marmot, was shown in a 2010 study to actually thrive in the face of climate alterations–a phenomenon scientists attributed to earlier-spring plant growth. But they predicted the benefits would be short-lived due to an increasingly serious climatic pitfall: drought.

Meanwhile, as temperatures continue to rise, other wildlife and insects are expected to flourish outright, including certain invasive species that will be able to expand their ranges and survive winters in new places, as well as non-invasive species. A recent Discovery news article highlighting climate-change winners focused on the brown argus butterfly, which has found a new host plant and a larger range; the albatross, whose food-finding ability has gotten a boost from shifting wind patterns; and the Australian gray nurse shark, whose population could boom if warmer waters reunite two separate populations. Also, melting Arctic ice could provide new feeding opportunities for orcas–but if so, two species it preys on, belugas and narwhals, would move into the climate-change losers column.

Sockeye salmon rely on a magnetic map to navigate home after years spent at sea. Credit: Putman et al., Current Biology

Scientists have long known that various marine animals use the earth’s magnetic forces to navigate waters during their life cycles. Such inherent navigational skills allow animals return to the same geographic area where they were born, with some migrating thousands of miles, to produce the next generation of their species.

As hatchlings, sea turtles scuttle from their sandy birthplace to the open sea as if following an invisible map, and, as adults, the females return to that spot to lay their own eggs. Bluefin tuna home in on their natal beaches after years at sea to spawn. Similarly, mature sockeye salmon leave open water after gorging on zooplankton and krill to swim back to the freshwater streams and rivers in which they were born.

But the mechanisms underlying this behavior are not well understood for most species, including the silver-bellied salmon. Previous studies suggest that tiny variations in earth’s magnetic field might have something to do with it, but research has been mostly limited to laboratory experiments—until now.

Using fisheries data spanning 56 years, researchers examined sockeye salmon’s mysterious sense of direction in their natural habitat. The findings, reported online today in Current Biology, show that sockeye salmon “remember” magnetic values of geographic locations. They imprint their birth location on this map when they leave their freshwater home for the sea, and use it as a compass during their journey back several years later, successfully returning home to spawn.

The salmon in this study originate in British Columbia’s Fraser River. They typically spend two to four years at sea, distributed widely throughout the Gulf of Alaska. As ruby-colored adult salmon, they begin their trek home. But on their way, they encounter a roadblock: Vancouver Island, the top of a submerged mountain range that stretches for 285 miles from the Juan de Fuca Strait in the south to Queen Charlotte Straight in the north. To get back to the Fraser River, the fish have to choose—the northern inlet or the southern inlet?

If the fish did possess some internal GPS that uses earth’s magnetic field as a map, researchers expected to see the salmon’s choice of inlet change in predictable ways over the years. This is because the planet’s magnetic field doesn’t remain constant; the field’s intensity and small-scale patterns change gradually over time through a process called geomagnetic field drift, caused mainly by movement in the Earth’s fluid core.

And that’s exactly what researchers observed: salmon showed a greater preference in a given year for the inlet that most closely resembled the magnetic signature of the Fraser River when they swam from it two years earlier. Their homeward route reflected how closely the field at each entryway, at the time of their return, resembled the field that the salmon experienced two years before, when they left the river to forage at sea.

Sockeye Salmon from Fraser River in British Columbia typically spend two to four years at sea, feeding on zooplankton. Credit: Current Biology, Putman et al.

Specifically, as the difference in the magnetic field’s strength between the Fraser River and Queen Charlotte Strait decreased, a higher proportion of salmon migrated through the northern inlet. Likewise, when the difference in magnetic intensity between the river and the Strait of Juan de Fuca decreased, a higher proportion of salmon migrated through the southern inlet.

For salmon, this ability is important, and in some cases, a matter of life and death. Efficiently navigating from foraging grounds to coastal breeding areas means more time spent feeding in open water, which translates into more energy for the journey home, researchers say. The imprinting capacity also ensures salmon reach their spawning sites at the right time.

Understanding this capacity may have implications for both wild and farmed salmon, a commercially important fish. For the last decade, salmon has been the third most consumed type of seafood in the United States, behind canned tuna and shrimp, with the average American citizen chowing down on two pounds of the fish per year.

“The Earth’s magnetic field is quite weak compared to the magnetic fields that humans can produce,” said study author Nathan Putman, a professor in the fisheries and wildlife department at Oregon State University, in a statement. “If, for instance, hatchery fish are incubated in conditions with lots of electrical wires and iron pipes around that distort the magnetic field, then it is conceivable that they might be worse at navigating than their wild counterparts.”

You may have never seen a zebrafish in person. But take a look at the zebrafish in the short video above and you’ll get to see something previously unknown to science: a visual representation of a thought moving through a living creature’s brain.

A group of scientists from Japan’s National Institute of Genetics announced the mind-boggling achievement in a paper published today in Current Biology. By inserting a gene into a zebrafish larvae—often used in research because its entire body is transparent—and using probe that detects florescence, they were able to capture the fish’s mental reaction to a swimming paramecium in real time.

The key to the technology is a special gene known as GCaMP that reacts to the presence of calcium ions by increasing in florescence. Since neuron activity in the brain involves rapid increases in concentrations of calcium ions, insertion of the gene causes the particular areas in a zebrafish’s brain that are activated to glow brightly. By using a probe sensitive to florescence, the scientists were able to monitor the locations of the fish’s brain that were activated ay any given moment—and thus, capture the fish’s thought as it “swam” around the brain.

Zebrafish embryos and larvae are often used in research because they are largely translucent. Image via Wikimedia Commons/Adam Amsterdam

The particular thought captured in the video above occurred after a paramecium (a single-celled organism that the fish considers a food source) was released into the fish’s environment. The scientists know that the thought is the fish’s direct response to the moving paramecium because, as an initial part of the experiment, they identified the particular neurons in the fish’s brain that respond to movement and direction.

They mapped out the individual neurons responsible for this task by inducing the fish to visually follow a dot move across a screen and tracking which neurons were activated. Later, when they did the same for the fish as it watched the swimming paramecium, the same areas of the brain lit up, and the activity moved across these areas in the same way predicted by the mental maps as a result of the paramecium’s directional movement. For example, when the paramecium moved from right to left, the neuron activity moved from left to right, because of the way the brain’s visual map is reversed when compared to the field of vision.

This isn’t the first time that GCaMP has been inserted into a zebrafish for imaging purposes, but it is the first time that the images have been captured as a real-time video, rather than a static image after the fact. The researchers accomplished this by developing an improved version of GCaMP that is more sensitive to changes in calcium ion concentration and gives off greater levels of florescence.

The accomplishment is obviously a marvel in itself, but the scientists involved see it leading to a range of practical applications. If, for example, scientists had the ability to quickly map the parts of the brain affected by a chemical under consideration as a drug, new and effective psychiatric medications could be more easily developed.

They also envision it opening the door to a variety of even more amazing—and perhaps a bit troubling (who, after all, really wants their mind read?)—thought-detecting applications. “In the future, we can interpret an animal’s behavior, including learning and memory, fear, joy, or anger, based on the activity of particular combinations of neurons,” said Koichi Kawakami, one of the paper’s co-authors.

It’s clearly some time away, but this research shows that the concept of reading an animal’s thoughts by analyzing its mental activity might move beyond science fiction to enter the realm of real world science applications.

The Nopoli rock-climbing goby. Photo: Takashi Maie

Species evolve extreme adaptations to contend with the rigors of their environment. Microbes thrive in Yellowstone’s boiling springs; kangaroo rats can live without ever taking a sip of water in the scorching U.S. Southwest; monarch butterflies can journey 3,000 miles just to enjoy a bit of Mexican sun. And to colonize new habitats, determined little fish climb their way up Hawaiian waterfalls with their suction-cup mouths, like reverse wall ball toys.

This superhero-like fish, the Nopili rock-climbing goby, are members of the Gobiidae family. Gobies are one of the largest fish families in the world, with around 2,000 species sharing the nomenclature. Many live in streams on volcanic islands like Hawaii, where life isn’t easy for these small, versatile fishes. Their stream homes are often subjected to lava flows, hurricanes and flash floods—and yet still the gobies persist. After a landslide creates vertical obstacles or a storm reworks the flow of water, those tenacious fishes inevitably turn up in the new upstream habitat, even if it’s separated from downstream areas by steep waterfalls.

To achieve this feat, gobies rely upon their singular evolution. All gobies possess an abdominal sucker, formed millennia ago when ancestral gobies’ pelvic fins fused. To scale waterfalls, most of the fishes use so-called “powerburst” climbing. They attach themselves to the slick wall behind a waterfall using their ventral sucker then rapidly undulate their tails, resulting in a shimmying action that slowly propels their flailing, sucking bodies up the waterfall.

The Nopili rock-climbing goby takes wall sucking to another level, however. Its mouth, located on the underside of its head like a cleaner fish, forms a formidable sucker that it uses to inch its way up waterfalls. Like a mountain climber, it takes turns sticking to the wall with its abdominal and oral suckers, slowly but steadily making its way up the sheer, wet rock. In Hawaii, these fish climb waterfalls up to nearly 330 feet tall.

So how did the Nopili rock-climbing goby pull off this super sucker mouth adaptation, while all of its relatives have to make due with just a measly abdominal sucker? The clue likely lies in the species’ feeding strategy. Most other gobies feed on small invertebrates or other fish, but the Nopili rock-climbing goby prefers to scrape tiny bits of algae, called diatoms, off rocks using a mouth-sucking motion mirroring the same movements it uses to climb walls. For an evolutionary scientist, this begs the question of whether the fish’s mouth first evolved for eating and then shifted to wall sucking, or vice versus. Scientists call this kind of evolutionary co-opting “exaptations.”

Researchers from Clemson University and Saint Cloud State University wanted to crack this chicken-or-egg puzzle, so they decided to compare the oral mechanisms of feeding versus climbing in the Nopili rock-climbing goby. If the fish uses its mouth in two very different ways for feeding and climbing, then exaptation likely wouldn’t deserve credit for the interesting adaptation. On the other hand, if the same movements were at play for both activities, then the fish may have simply applied a regular activity (feeding or climbing) to a new role.

The researchers donned snorkeling gear and scooped up several wall-sucking gobies from Hakalau stream on Hawaii Island, in 2005 and 2011. They transferred the fish to a lab, where they observed several of their research subjects’ feeding patterns using high-speed video cameras attached to different sides of the aquarium. In another tank, the researchers also created a faux waterfall using Plexiglas situated at a 62-degree angle. They challenged the remaining fish to climb this wall and filmed those fish during their waterfall-scaling exertions.

From the videos, the researchers identified 23 anatomical landmarks involved in feeding and climbing. After statistically analyzing their results, the researchers report in a PLoS One paper published last week that they found that the Nopili rock-climbing goby’s climbing and feeding movements differed significantly. In other words, the fish are using different movements for feeding and for climbing. The differences, however, were small, and some of the behaviors were so similar they could nearly be superimposed. The puzzling combination of similarities and differences stumped the researchers, and they realized that more investigations would be needed before they could definitively tease out the species’ evolutionary history of feeding and sucking.

“However, strict similarity between feeding and climbing kinematics might not be a fair expectation, even if exaptation had occurred,” they write in their paper. “It may not be reasonable to expect patterns for one behavior to remain completely unchanged after being applied to another function.”

Like most things in science, goby evolution is complex and may not prescribe to a clear-cut explanation. “Exaptation with modification” may have to suffice for elucidating the Nopili rock-climbing goby’s unique talents—at least for now.

2012 was a big year for squid science. Photo Credit: © Brian Skerry, www.brianskerry.com

Despite covering 70 percent of the earth’s surface, the ocean doesn’t often make it into the news. But when it does, it makes quite a splash (so to speak). Here are the top ten ocean stories we couldn’t stop talking about this year, in no particular order. Add your own in the comments!

2012: The Year of the Squid From the giant squid’s giant eyes (the better to see predatory sperm whales, my dear), to the vampire squid’s eerie diet of remains and feces, the strange adaptations and behavior of these cephalopods amazed us all year. Scientists found a deep-sea squid that dismembers its own glowing arm to distract predators and make a daring escape. But fascinating findings weren’t relegated to the deep: at the surface, some squids will rocket themselves above the waves to fly long distances at top speeds.

James Cameron Explores the Deep Sea Filmmaker James Cameron has never shied away from marine movie plots (See: Titanic, The Abyss), but this year he showed he was truly fearless, becoming the first person to hit the deepest point on the seafloor (35,804 feet) in a solo submarine. While he only managed to bring up a single mud sample from the deepest region, he found thriving biodiversity in the other deep-sea areas his expedition explored, including giant versions of organisms found in shallow water.

Small fish, such as these schooling sardines, received well-deserved attention for being an important part of the food chain in 2012. Photo Credit: © Erwin Poliakoff, Flickr

Small Fish Make a Big Impact Forage fish—small, schooling fish that are gulped down by predators—should be left in the ocean for larger fish, marine mammals and birds to eat, according to an April report from the Lenfest Forage Fish Task Force. These tiny fish, including anchovies, menhaden, herring and sardines, make up 37% of the world’s catch, but only 10% are consumed by people, with the rest processed into food for farmed fish and livestock. With the evidence mounting that forage fish are worth more as wild fish food, state governments and regional fishery management councils are making moves to protect them from overfishing.

Marine Debris and Plastic Get Around In June, a dock encrusted with barnacles, sea stars, crabs and other sea life washed ashore on the coast of Oregon. It had floated across the Pacific from a Japanese port more than 5,000 miles away—a small piece of the estimated 1.5 million tons of marine debris set afloat by the 2011 Tohoku tsunami. But that’s not the only trash in the sea. Researchers found ten times as much plastic in the “pristine” Antarctic oceans than they expected. Some species are even learning to adapt to the ubiquitous ocean plastic.

These tropical tangs and their coral reef habitat are protected at Hawaii’s Papahanaumokuakea Marine National Monument. Photo Credit: Claire Fackler, CINMS, NOAA, Flickr

Taking Measure of Coral Reef Health Australia’s iconic Great Barrier Reef, so large it can be seen from space, is not doing well. An October study found that since 1986, half of the living coral has died because of warming water, predation and storm damage. And it’s not just Australia: the December Healthy Reefs report gave most Mesoamerican reefs a “poor” rating. It’s hard to escape that gloom, but there were glimmers of hope. Some coral species proved able to adapt to warmer water, and changing circulation caused by the warming ocean may create refuges for coral reef habitat.

Shark Finning Slowing Down? The fishing practice of shark finning—slicing off a shark’s fins before tossing it back in the ocean to slowly sink and suffocate—began its own slow death in 2012. A steady stream of U.S. states have banned the sale of shark finsning; the European Union will now require fisherman to land sharks with their fins on; four shark sanctuaries were created in American Samoa, the Cook Islands, Kosrae and French Polynesia; and, in July, China announced that official banquets would be prohibited from serving shark fin soup (although the ban may take up to three years to go into effect).

Arctic ice reached an all-time low in 2012. Photo Credit: NASA/Kathryn Hansen

Arctic Sea Ice Hits All-Time Low On September 16, sea ice extent reached a record low in the Arctic, stretching 3.41 million square kilometers—that’s 49% lower than the 1979-2000 average minimum of 6.7 million square kilometers. What’s more, its melt rate is increasing: 2012 had the largest summer ice loss by more than one million square kilometers. This change is expected to affect ecosystems—from polar bears to phytoplankton—and accelerate warming in the area, eventually melting Greenland’s ice sheet and raising sea level dramatically.

Hurricane Sandy Elevates Awareness of Sea-Level Rise This year certainly opened our eyes to the severity of climate change and sea-level rise. The east coast of the U.S., where scientists project sea-level will rise three to four times faster than the global average, got a glimpse of its effects when Hurricane Sandy caused $65 billion in damage, took at least 253 lives, and flooded Manhattan’s subways in October. The disaster inspired The Economist, Bloomberg Businessweek and other major news sources to take a closer look at climate change and what it means for us all.

Using satellite photos, researchers counted twice as many emperor penguins living in Antarctica than they thought existed. Photo Credit: Martha de Jong-Lantink, Flickr

Counting Ocean Animals from Space Scientists took advantage of satellite technology this year to learn more about ocean wildlife. The first satellite-driven census of an animal population discovered that there are twice as many emperor penguins in Antarctica as previously thought, including seven new colonies of the large flightless birds. A second study tracked the travels of sea turtles by satellite, which could help researchers get a better idea of where they might interact with fisheries and accidentally end up caught in a net.

The Ocean Gets a Grade The first tool to comprehensively assess ocean health was announced in August 2012—and the ocean as a whole received a score of 60 out of a possible 100. This tool, the Ocean Health Index, is novel in that it considered ten ways the ocean supports people, including economies, biodiversity, and recreation. The U.S. scored a 63, ranking 26th globally, while the uninhabited Jarvis Island took home an 86, the top grade of the 171 rated countries.

–Hannah Waters, Emily Frost and Amanda Feuerstein co-wrote this post

  Learn more about the ocean from the Smithsonian’s Ocean Portal.