See the Horned Lizard’s Bloody Defense Mechanism in Slo-Mo

There are all kinds of ways to get somebody to leave you alone. You can hide and hope they go away. You can take off. You can puff yourself up and make yourself bigger. You can shoot blood out of your eyeballs (well, you probably can’t). For horned lizards like the one in the National Geographic video above, the best strategy is whichever one of these targets a predator's weaknesses.

Horned lizards, also commonly and inaccurately known as horny toads, are funny little beasts. These desert reptiles eat venomous ants, and lots of them, because ants are mostly crunchy shell with little nutritional value. In order to accommodate all those ants, some horned lizards have big bellies.

Those bellies help the lizards get the nutrients they need, but they’re also somewhat of a liability, since a pancake-shaped body is not exactly aerodynamic. "They are short-legged and stubby-bodied," University of Calgary herpetologist Larry Powell told the BBC. "When they run, they give it their best, but they're just not built for speed." 

In other words, fleeing is not a great first option. So when a predator approaches, horned lizards perform a simple and instantaneous calculation, first identifying their attacker’s species, then selecting the best way to scare it off.

Lots of animals eat horny toads, or try to. Among the lizards’ foremost predators are snakes, canids like coyotes and dogs, and wild cats. Each snake species hunts differently, which means a different tactic for each. A fast snake can’t be outrun, so the lizards depend on camouflage to hide from them. Ambush predators like rattlesnakes, on the other hand, wait for prey to come to them, and can therefore often be avoided by running like hell on little lizard legs in the other direction. Many snakes try to swallow their prey whole. The lizards’ solution is to make themselves so puffy and big that they won’t even fit in a snake’s mouth.

And then there are the wild dogs and cats. Here’s where all those ant snacks may come in handy. Scientists believe horned lizards borrow chemicals from their venomous food and mix them into their blood. When a large predator gets too close, the lizard lets loose with a face-stream of hot, nasty-tasting, nose-stinging blood. It’s not elegant, but it seems to work; canids and wild cats hate it. And as the would-be lizard-eater paws at its face, the lizard can scoot away. 

Image from National Geographic

Andreas Trepte via Wikimedia Commons // CC BY-SA 2.5
Climate Change Has Forced Mussels to Toughen Up
Andreas Trepte via Wikimedia Commons // CC BY-SA 2.5
Andreas Trepte via Wikimedia Commons // CC BY-SA 2.5

Researchers writing in the journal Science Advances say blue mussels are rapidly evolving stronger shells to protect themselves against rising acid levels in sea water.

Bivalves like mussels, clams, and oysters aren’t good swimmers, and they don’t have teeth. Their hard shells are often the only things standing between themselves and a sea of dangers.

But even those shells have been threatened lately, as pollution and climate change push the ocean's carbon dioxide to dangerous levels. Too much carbon dioxide interferes with a bivalve’s ability to calcify (or harden) its shell, leaving it completely vulnerable.

A team of German scientists wondered what, if anything, the bivalves were doing to cope. They studied two populations of blue mussels (Mytilus edulis): one in the Baltic Sea, and another in the brackish waters of the North Sea.

The researchers collected water samples and monitored the mussel colonies for three years. They analyzed the chemical content of the water and the mussels’ life cycles—tracking their growth, survival, and death.

The red line across this mussel larva shows the limits of its shell growth. Image credit: Thomsen et al. Sci. Adv. 2017

Analysis of all that data showed that the two groups were living very different lives. The Baltic was rapidly acidifying—but rather than rolling over and dying, Baltic mussels were armoring up. Over several generations, their shells grew harder.

Their cousins living in the relatively stable waters of the North Sea enjoyed a cushier existence. Their shells stayed pretty much the same. That may be the case for now, the researchers say, but it definitely leaves them vulnerable to higher carbon dioxide levels in the future.

Inspiring as the Baltic mussels’ defiance might be, the researchers note that it’s not a short-term solution. Tougher shells didn’t increase the mussels’ survival rate in acidified waters—at least, not yet.

"Future experiments need to be performed over multiple generations," the authors write, "to obtain a detailed understanding of the rate of adaptation and the underlying mechanisms to predict whether adaptation will enable marine organisms to overcome the constraints of ocean acidification."

University of Adelaide
Scientists Find Potential Diabetes Drug in Platypus Venom
University of Adelaide
University of Adelaide

The future of diabetes medicine may be duck-billed and web-footed. Australian researchers have found a compound in platypus venom (yes, venom) that balances blood sugar. The team published their results in the journal Scientific Reports.

So, about that venom. The platypus (Ornithorhynchus anatinus) may look placid and, frankly, kind of goofy, but come mating season, the weaponry comes out. Male platypuses competing for female attention wrestle their opponents to the ground and kick-stab them with the venom-tipped, talon-like spurs on their back legs. It’s not a pretty sight. But it is an interesting one, especially to researchers.

Animal venoms are incredible compounds with remarkable properties—and many of them make excellent medicine. Many people with diabetes are already familiar with one of them; the drug exenatide was originally found in the spit of the venomous gila monster. Exenatide works by mimicking the behavior of an insulin-producing natural compound called Glucagon-like peptide 1 (GLP-1). The fact that the lizard has both venom and insulin-making genes is not a coincidence; many animal venoms, including the gila monster’s, induce low blood sugar in their prey in order to immobilize them.

It’s a good strategy with one flaw: GLP-1 and compounds like it break down and stop working very quickly, and people who have trouble making insulin really need their drug to keep working.

With this issue in mind, Australian researchers turned their attention to our duck-billed friends. They knew that platypuses, like people, made GLP-1 in their guts, and that platypuses, like gila monsters, make venom. The real question was how these two compounds interacted within a platypus’s body.

The researchers used chemical and genetic analysis to identify the chemical compounds in the guts and spurs of platypuses and in the guts of their cousins, the echidnas.

They found something entirely new: a tougher, more resilient GLP-1, one that breaks down differently—and more slowly—than the compounds in gila monster spit. The authors say this uber-compound is the result of a "tug of war" between GLP-1’s two uses in the gut and in venom.

"This is an amazing example of how millions of years of evolution can shape molecules and optimise their function," co-lead author Frank Gutzner of the University of Adelaide said in a statement.

"These findings have the potential to inform diabetes treatment, one of our greatest health challenges, although exactly how we can convert this finding into a treatment will need to be the subject of future research."


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