It comes as no surprise to regular readers of mine that I have a special place in my heart for parasites. I have waxed poetic about their global dominion, but usually, I focus on the animal kingdom’s most malicious moochers. Today, though, is all about plant parasites. Specifically, this lovely orchid:
Meet Gastrodia pubilabiata, a plant that survives in the most un-planty way. That lack of green isn’t because it’s dying—it doesn’t photosynthesize. Instead, it’s what’s known as a mycoheterotroph: it relies on fungi for food. But according to a new paper in Ecology, this particular species doesn’t just suck the life from its mushroom hosts. Instead of offering nectar or other rewards for its pollinators, it uses the smell of the fungi rotting corpses to draw the flies that transport its reproductive dust. Continue reading “Orchid Mooch Steals Nutrients From Mushroom And Uses It To Fake Out Fly Pollinators”
A well-fed assassin bug in the lab at the University of Queensland. Photo Credit: Christie Wilcox
In one of his journal entries from his time aboard The Beagle, Charles Darwin told of a “great black bug” and how it boldly sucked blood from his finger through its large mouthpart. The creature was likely Triatoma infestans, a kissing bug—one of the almost 7,000 species of assassin bug that are now described. Like its kin, it’s armed with an ominous looking proboscis which it uses to slurp up its meals.
But the kissing bug is one of only a few assassin bugs with vampiric tastes. Most are much more murderous, preferring to use potent venoms to paralyze a their prey so they can liquify them from the inside out, then suck their soupified meal through their needle-like mouths.
It was that behavior which intrigued Andrew Walker, a molecular entomologist and postdoctoral fellow in the Institute for Molecular Bioscience at The University of Queensland. He and his colleagues were curious what the paralyze then liquify-and-slurp venom looked like. “We wanted to see if assassin bugs had venom that was similar in composition to other venomous animals due to convergent evolution, or if the different feeding physiology would result in a different composition,” he said. And when their research began, essentially no one has looked at their venoms—”almost nothing was known about them.”
We’re about a month away from the 60th annual rattlesnake roundup in Sweetwater Texas. The event proudly calls itself the world’s largest—and for good reason. Last year, nearly 8,000 lbs of snakes were killed in this barbaric slaughterfest. But there are so many reasons why this all-out assault on Texas’ reptiles is a terrible idea. Rattlesnakes have complex social lives, can live for decades, and are essential to their native ecosystems. As predators, they help keep populations of mice and other small animals in check, which may ultimately help protect us from disease. And, of course, they help disperse seeds, altering the floral landscapes they slither through.
Wait—what was that last one?
If seed dispersal sounds less like something a snake does and more the purview of mammals and birds, that’s because until now, snakes weren’t thought of as seed dispersers—mostly because, well, they generally don’t eat plants or fruits (at least not willingly). And their smooth scaly skin doesn’t exactly give much for burs to stick to. But a new study in Proceedings of the Royal Society Bsuggests that rattlesnakes in the southwestern US may be acting as ecosystem engineers by spreading seeds. Continue reading “Another Reason To Save Snakes: They Disperse Seeds (Probably)”
Tide pools reveal surprising influence of marine life on seawater chemistry. Photo Credit: Ethan Daniels/Shutterstock
One of the many consequences of rising atmospheric carbon dioxide is ocean acidification—the lowering of seawater pH as CO2 chemically reacts with dissolved ions in seawater. Scientists have found that more acidic waters are dangerous to many species, especially structure-builders like corals, and thus the potential drop in pH predicted in the future would be devastating to marine habitats.
So it’s not surprising that many scientists are actively looking for ways to mitigate this for coastal ecosystems, where losses could be especially impactful ecologically and economically. But the answer may be right in front of them: marine life is already able to buffer drops in pH, finds new research in Scientific Reports.Continue reading “Marine Life Can Buffer Ocean Acidity, Study Finds”
The first wave of invaders likely numbered 48 or more, according to new research. (Credit: kzww/Shutterstock)
In 1992, Hurricane Andrew ripped it’s way across the southern US. Southern Florida, where Andrew made landfall, was one of the hardest hit areas. It’s estimated that over 100,000 homes were damaged, and 63,000 were destroyed—among them an expensive beachfront house with a very large and memorable aquarium. That aquarium contained six lionfish, and when it broke, they were swept into Biscayne Bay. And so began the lionfish invasion into the Atlantic. Continue reading “Dozens—Perhaps Even Hundreds—of Lionfish Likely Launched the Atlantic Invasion”
A seascape of fear? New study suggests fear of sharks shapes ecosystems. Photo Credit: Narchuk/Shutterstock
It’s kind of incredible how our fears can shape our behaviors. When Jaws was released in 1975, it fundamentally changed how we interact with sharks. In the years that followed, we hunted these large marine predators more intensely, and came to view them as terrible monsters—attitudes scientists still fight to this day. But while our fears are largely unfounded, there are lots of species that have good reason to be wary of these awesome fish. Scientists have now discovered that such fear can ripple through the reef ecosystem, impacting community structure all the way down to seaweeds.
There’s no doubt that sharks can be a bit terrifying, especially if you’re a snack-sized fish. Scientists have long suspected that such fear can alter behavior. Just like people that are scared of sharks avoid beach vacations, preyed upon fish might try to avoid areas where sharks roam in the hopes of steering clear of those sharp, pointy teeth. And where the fish avoid, the species they eat proper, a marine version of ‘when the cat’s away, the mice will play.’ Thus by creating landscapes of fear—or, in this case, seascapes—sharks could shape entire ecosystems even if the amount of prey they actually consume is negligible.
Not only do we not know how fear of sharks might shape marine habitats, our overall understanding of how sharks interact with other species is lacking. Despite our annual fin-fests and obsession with these fearsome fish, “we still only have a very basic understanding of their ecological roles in nature,” said Doug Rasher, a senior research scientist at Bigelow Laboratory, in a press release. So he and his colleagues decided to look a little closer, zeroing in on the impacts of sharks on shallow reef habitats off the coast of Fiji.
A diagram of the shallow lagoons studied. Figure 1 a and b from Rasher et al. 2017.
The well-lit, shallow lagoons of Fiji’s largest island, Viti Levu, are ideal habitat for tasty seaweeds like Turbinaria conoides, a favorite of herbivorous fish. Since the islanders established a no-take reserve protecting the fringing reef of Votua Village, Korolevu-i-wai, in 2002, the abundance of seaweeds has dropped dramatically, particularly in the more isolated back reefs, making room for corals to rebound. But not all areas of the lagoons are equally seaweed-free. The algae remain in the shallowest reef tops. Rasher and his colleagues wanted to understand why.
The research team put GoPros in the water to observe which fish were eating algae as well as when and where sharks were moving around the lagoons. They also surveyed for the presence of algae-eating fish during high and low tides, and to determine seaweed location and abundance. In addition, they calculated fish feeding rates on algae in shallow and deeper back reef areas during different tidal phases by deploying measured amounts of algae for the fish to snack on.
When they brought all that data together, a clear pattern emerged. The biggest predators like blacktip reef sharks (Carcharhinus melanopterus), whitetip reef sharks (Triaenodon obesus,) and tawny nurse sharks (Nebrius ferrugineus) only entered the back reefs when tides were high—the researchers estimated that on average, each 40 square meter section of backreef is trawled by 4 to 5 reef sharks and 1 jack during each high tide. And when that happened, the herbivorous fishes like unicornfishes (Naso lituratus and N. unicornis) pretty much stopped eating and disappeared, presumably steering clear of the meandering predators.
That meant that the shallow reef tops received very little attention by the algae-eaters, as they could only be accessed when the reef sharks entered the shallows to feed. And in turn, those reef tops sported about 20 times the amount of seaweed. The researchers ruled out the possibility that these algae just do better on the reef tops for other reasons, like increased amounts of light, by comparing the growth rates of caged weeds in both areas. So the stark difference between the tops and deeper troughs in the backreef appears to be driven mostly by the fish’s fear of sharks.
A 2013 study in Shark Bay, Australia, had similar results, finding the risk of tiger shark predation affected the nature and abundance of seagrasses. Combined, they paint a much more interesting picture of the role sharks play in marine habitats. Their effects go far beyond what they consume directly, so their mere presence can “actually shape the way [an ecosystem] looks and functions,” explained Rasher.
On the practical side, these results suggest that we might be able to reduce our fishing impacts by taking this kind of thing into account. “Our example highlights the need to consider predator effects in ecosystem-based management,” the authors write in their conclusions. “With knowledge of predator movements and resultant herbivore migrations, resource managers could mitigate this negative human impact in similar ecosystems by regulating not only where but when herbivores are harvested.”
And ultimately, they underscore the need to better understand the ecological importance of sharks and other large predators. “Large apex predator sharks as well as the large mesopredator reef sharks studied here are now generally rare or absent on coral reefs exposed to heavy fishing pressure; thus, the effects we documented may already be extinguished from many places,” the authors write. “Despite these difficulties, we need to study Earth’s remaining wild places where predators still abound, and capitalize on chance events and variability in nature… Only then can we understand the ramifications of predator loss or recovery.”
Citation: Rasher et al. 2017. Cascading predator effects in a Fijian coral reef ecosystem. Scientific Reports 7, 15684. doi:10.1038/s41598-017-15679-w
After a win, mangrove crabs (Perisesarma eumolpe) will gloat to keep opponents from going for round two. Photo Credit: Marut Sayannikroth/Shutterstock
From touchdown dances to victory laps, we all love to bask in the glory after a big win. So do mangrove crabs. After a fierce physical altercation, victorious male crabs sometimes stridulate, planting one claw into the ground and rubbing it vigorously with the other to both visibly and audibly revel in their triumph. But the purpose of this gloating was unclear, as little research has examined the consequences of such victory displays. Now, a new paper in Ethology may have an explanation: rejoicing discourages the losing crabs from attempting a rematch. Continue reading “Crab Gloats After Winning To Discourage Rematches”
C’mon, you’re not really afraid of this cute little guy, are ya? Photo Credit: Plamuekwhan/Shutterstock
Few groups of animals are as feared as spiders. Doctors estimate at least 5% of people are arachnophobic, meaning they are terrified of the eight-legged critters. But such fear is largely misplaced. Of the nearly 47,000 species of spider on the planet, only 200 or so can actually bite through our tough skin and deliver venom that causes any kind of reaction. And of those, only a few are considered truly dangerous. Rather than fearing them, we should be in awe of just how incredibly diverse, successful, and unique these animals are.
Fishermen working with a cooperative dolphin to enhance their catch. Photo Credit: Carolina Stratico
When the mullet migrate northward, the fishermen in Laguna, Brazil are waiting. They rise early and take their places in line, waist-deep in the water, tarrafa—a kind of circular throwing net—in hand. Without a word, the dolphins arrive, herding schools of mullet towards the fisher line. The fishers say that the dolphins are an essential part of their fishing; they wait to fish until their marine helpers to arrive, in some cases standing for an hour or more, calling to the animals: “let’s work”. The fishers work as a unit, trading out their spots in line as the dolphins fill their nets.
But while the humans are united, the dolphin community is divided. Only some of the population cooperate with fishers in this manner. Scientists discovered that the ones that work with people form their own cohesive social network, separate from the other dolphins in the area. “The cooperative fishery appears to have influenced the structuring of this bottlenose dolphin population into social communities,” explain Bianca Romeu and her colleagues at Brazil’s Universidade Federal de Santa Catarina in a new paper this month in the journal Ethology. Their latest work reveals the depth of this rift: the cooperative dolphins don’t just behave differently, they communicate differently, too.
These Asian amur sea stars (Asterias amurensis) were found ~5,000 miles from home on the Oregon coast. Image provided by Oregon State University
March 11, 2011, 2:46 PM, 45 miles east of Tōhoku, Japan. Fifteen miles beneath the waves, a magnitude-9 megathrust earthquake strikes. The Pacific and Eurasian tectonic plates suddenly shift, shaking the surrounding crust for six minutes and creating a tidal wave almost 40 meters high, which races towards the coast of Japan. In the hours that follow, it claims at least 15,894 lives, with thousands more unaccounted for. More than a million buildings are damaged or destroyed, causing nearly $200 billion in damages.
The remnants of those buildings and all sorts of debris liberated by the moving waters have since spread the tsunami’s legacy far beyond the site of impact. As a new study in the journal Science explains, thanks to objects set adrift by the tsunami’s waves, more than two hundred and eighty species have been found on the wrong side of the ocean.
