Snakes, with their sleek, slithering shape, are unmistakable amongst the reptiles. Yet for decades, scientists have been debating just how these limbless lizard relatives ended up with their distinctive, elongated body.
On one side are scientists who argue that the serpentine shape was an aquatic adaptation. Many snake traits, including an elongated body and reduced limbs, are also features of swimming animals (think whales and dolphins, for example, which have lost their hind limbs). Early evidence also suggested that snakes were closely related to mosasaurs, the terrifying and extinct group of lizards that were woven into pop culture the moment one was fed a great white shark in Jurassic World. Non-theatrically, these marine reptiles ruled the seas during the Cretaceous, and possessed many snake-y features, including a jaw which stretches for large prey. The discovery of extinct marine snakes with hindlimbs, including Pachyrhachis, Haasiophis, and Eupodophis, seemed further proof of a marine origin.
But later analyses have suggested that Pachyrhachis and others are secondarily marine, the offshoots of a more derived snake group, and the connection between snakes and mosasaurs has come under suspicion. The prevailing hypothesis is now that snakes evolved on land — or, even more specifically, in it. A burrowing or ‘fossorial’ lifestyle could also produce long, skinny bodies and reduced limbs. More recent finds like Najash, Dinilysia, and Coniophis, which date back further than Pachyrhachis, all lived on land. But the evidence for a largely underground existence isn’t conclusive, either, and some hold to the idea that snakes were born in the sea.
The debate has continued so long because there is a dearth of snake fossils to rely upon. Snake bodies are by and large small and fragile, with thin bones that do not lend easily to fossilization. So scientists have had little material to work with when trying to determine changes over time.
A new fossil hopes to end the debate once and for all. A paper published this week in Science describes what appears to be a four-legged burrowing snake from Brazil. “Here it is, an animal that is almost a snake” says David Martill, a paleobiologist from the University of Portsmouth, “and it doesn’t show any adaptations to being in an aquatic environment.” But is it really that cut-and-dry? While the latest fossil find is making a splash in the news, it’s one of four noteworthy papers this year examining snake evolution, and placing the new study in context helps explain what makes the fossil so exciting, if controversial. Read More
It’s no secret that last year I had no love for Discovery Channel’s annual fin fest. Shark Week 2014 kicked off with yet another fake documentary, included a reprise of their infamous Megalodon mockumentary, and had what I might argue was the worst shark week special of all time, set right here in Hawaii. It was incredibly disheartening to see Discovery double down on the B.S. after the initial Megalodon special prompted an outpouring of anger from scientists and viewers. Given the drop in viewership from 2013 to 2014, it was clear that I wasn’t the only one disappointed by the channel’s choices, and that there were serious concerns coming from critics and fans alike. The disgustingly-awful Eaten Alive in December was simply the last straw; I was certain that there was no hope for the once-educational network. Then Rich Ross stepped up as the new president, stating that he was going to get rid of the faked footage and gaudy stunts, and suddenly, there was a glimmer of light in the deep, deep darkness.
Rich kept his promise, delivering a Shark Week that even softened the heart of the scientist dubbed its biggest critic, David Shiffman. In a public statement on his Facebook page, the PhD candidate at the University of Miami said he was “very pleased with the improvements this year.”
“There was a much higher focus on science and biodiversity, and greatly reduced fearmongering and pseudoscience. Some of the shows from this year will inspire kids to become scientists or conservationists, and I won’t have to correct misconceptions caused by this year’s programming when I speak to schoolchildren over the coming months!” (see his detailed reviews of each show here)
Even the ads were better, if you ask me: in place of the sexist, sensationalized chum spot from last year was this lovely beach scene, completely devoid of blood and gore:
But the real question is: did the rest of Discovery’s viewers feel the same way? Read More
The diamondback moth catterpillar (Plutella xylostella) may not look like much, but don’t be fooled by its generic caterpillar-y appearance; these larval lepidopterans are one of the world’s worst insect pests. Diamondback caterpillars gorge their way through cabbages, canola, broccoli, cauliflower, and kale, costing farmers $4-5 billion annually worldwide. The worst part is that these hungry beasts always seem to be a step ahead of pest management strategies, readily evolving resistance to every organic and synthetic chemical that farmers attempt to wipe them out with. But now, scientists have created a secret weapon that the bugs cannot resist: genetically modified males whose genes kill their female offspring. Read More
I have been living in Hawaii for six years now, and I have once, and only once, caught a glimpse of the snakes that call these islands home.
Yes, you read that right: there are snakes in Hawaii. Technically, there are two species that can be found here, but the yellow-bellied sea snake is so rare it almost doesn’t count. The other — the brahminy blindsnake — is actually quite common, though it’s easy to understand why it’s often overlooked: these small, black creatures only grow to be about six inches long and dwell in the dirt. They are often mistaken for worms because of their diminutive size and underground lifestyle. The same species can be found worldwide: natively throughout Asia and Africa and non-natively in several places, including Hawaii. They’re also the only species of snake that is entirely parthenogenic — no male has ever been collected. They simply don’t look or act like we think a snake should. And now, scientists have documented yet another trait that makes them stand out from their serpentine brethren: before swallowing, they will sometimes decapitate their meal. Read More
Cone snails are among the most venomous animals on the planet, with some species able to kill an adult human in a matter of minutes. Some species hunt worms, some hunt other snails, and some even hunt fast-moving fish, the last of which are the most dangerous to us. Evolutionary studies suggest that ancestral cone snails were worm-eaters, and that fish-eating is a relatively new phenomenon. Which begs the question: how does a snail go from a slow-moving worm-hunter to a quick-striking fish-hunter? A team of scientists thinks they may have found the answer: the snails turned defensive toxins into attack weaponry.
The flatworm Macrostomum hystrix isn’t exciting to look at. Its diet of microalgae doesn’t raise any eyebrows, and you probably wouldn’t even notice one if you came across it in its native habitat. But in the bedroom, these flatworms take kink to a whole new level: when they can’t find a partner, they will stab themselves in the head with their needle-like penises and inject sperm to self-fertilize. Read More
Given the enormous backlash to Western Australia’s ill-conceived shark cull last year, you would think that government officials would have come to realize that killing sharks is a terrible way to respond to shark bites (more than 100 shark scientists and 2/3 of Western Australians opposed that cull). But it appears that authorities in North Carolina have not learned from others’ mistakes: Oak Island Town Manager Tim Holloman announced this week that following two life-threatening bites, officials would “take appropriate action” and “eliminate” any shark they deem a potential threat. According to the L.A. Times:
If officials see aggressive behavior from any sharks near shore, such as darting in and out of the surf line or coming within about 100 feet of the beach, Holloman said, the officials are prepared to euthanize the animal.
“If they look like they’re posing a danger, we will authorize that action,” Holloman told the Los Angeles Times.
Let me be extremely clear: what happened to the two teenagers in Oak Island, N.C. this week is awful. My heart goes out to them and their friends and relatives. They have survived something terrible and life-altering, and I hope that they are being well supported and cared for. But killing any shark that comes within 100 feet of shore or displays “aggressive behavior” will not return their limbs — nor will it prevent anyone else from losing theirs. Read More
As far as natural selection is concerned, sex is just about everything. All activities a creature engages in are in service of reproduction. Not surprisingly, the nitty gritty cellular details of reproductive biology are thus of extreme interest to many scientists.
Biologically speaking, males are the members of a species that generate sperm while females produce eggs. But now, scientists from Japan have shown that a female fish can produce fully-functioning sperm—and would all the time, if it weren’t for the expression of a single gene. Read More
Today is World Oceans Day, a United Nations-recognized day of ocean celebration and action. This year’s theme is simple—Healthy oceans, healthy planet—with a focus on the problem of marine plastic, a topic I recently wrote about for Popular Science.
Around the internets, World Oceans Day has been making a lot of waves, with lots of great articles about the importance of marine environments and what all of us can do to make them healthier. It’s heartening to see the attention that this day is receiving, including the flood of posts using the hashtag on Twitter*.
Here are some of my favorites ocean posts from today: Read More
When you get right down to it, box jellyfish are little more than goo. The majority of their volume is mesoglea, a non-living, jello-like substance, which is sandwiched between two thin tissue layers. They have no teeth to bite with, no claws to scratch with — none of the weaponry we generally think of when we imagine a ruthless predator. Yet these boneless, brainless boxies are among the deadliest animals on Earth. The box jellyfish Chironex fleckeri can kill a full grown man in less than five minutes, and the venom it wields in its tentacles contains of some of the most rapid, potent toxins in the world.
Exactly what those toxins are, though, has remained somewhat of a mystery. Scientists have been trying to determine the composition of box jelly venom for decades, but have only uncovered some of its potent constituents. And while there’s still more to learn, last week, a research team from Queensland, Australia published the most extensive analysis of Chironex venom proteins to date, revealing some of the diverse arsenal that these gelatinous killers are equipped with. Read More