Evolution – Page 3 – Science Sushi

Venomous Frogs Are Super-Awesome, But They Are Not Going To Kill You (I Promise)

In the first chapter for my upcoming book Venomous (due out in 2016), I excitedly explain how nearly all the sundry branches of the tree of life have venomous leaves. I’m simply enthralled by the incredible diversity of venomous animals (and plants!) on this planet, from the tentacle-wielding jellies to the spiny scorpionfishes and, of course, the oft-feared and misunderstood snakes, spiders, and scorpions. But until today, there is one group that could not boast a single venomous member: the anurans, commonly known as frogs and toads. While there are plenty of poisonous ones, no one has ever found a venomous frog — that is, until now.

I know scientists are brazen, but I'm pretty sure that lead author Carlos Jared wouldn't hold this venomous Corythomantis greeningi with his bare hands if it were indeed "deadly". Photo by Carlos Jared c/o Current Biology 2015 — I know scientists are brazen, but I’m pretty sure that lead author Carlos Jared wouldn’t hold this venomous *Corythomantis greeningi* with his bare hands if it were indeed “deadly.”
Photo by Carlos Jared / Current Biology

Venomous animals are natural biochemists that take toxic to a whole new level. While it is true that venoms and poisons are both toxins, the two terms are not interchangeable. All toxins cause harm in low doses; Poisons are substances that cause such harm through ingestion, inhalation or absorption. To earn the title of venomous, on the other hand, an animal has to do more than just have toxins — they have to have a means of wounding their intended victims to force those toxins upon them. That “wounding” can be caused by any weapon of choice; jellies and other members of the phylum Cnidaria use specialized stinging cells that shoot out hollow tubes in less than a microsecond to deliver their potent venom. Snakes and spiders use fangs, the venomous fishes use spines, and the newest members of the venomous family — the frogs Aparasphenodon brunoi and Corythomantis greeningi — use their spiky heads. Continue reading “Venomous Frogs Are Super-Awesome, But They Are Not Going To Kill You (I Promise)”

Four-Legged Snake Shakes Up Squamate Family Tree – Or Does It?

A new fossil, named ____, claims to be a four-legged, burrowing snake. Figure 1 from Martill et al. 2015 — A new fossil, named *Tetrapodophis amplectus*, claims to be a four-legged, burrowing snake. (A) Counterpart, showing skull and skeleton impression. (B) Main slab, showing skeleton and skull impression.
Figure 1 from Martill et al. 2015

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. Continue reading “Four-Legged Snake Shakes Up Squamate Family Tree – Or Does It?”

Cone Snail Venom: The Best Offense Is A Good Defense

One of the most potent toxins in venomous cone snails likely started as a defense against hungry fish. Image from Figure 4, Jin et al. 2015 — One of the most potent toxins in venomous cone snails likely started as a defense against hungry fish.
Image from Figure 4, Jin et al. 2015

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.

Continue reading “Cone Snail Venom: The Best Offense Is A Good Defense”

These flatworms plunge their penises into their own heads to inject themselves with sperm (when they must).

A very ordinary flatworm with a very extraordinary way of reproducing. Photo © Ramm SA, Schlatter A, Poirier M, Schärer L. — A very ordinary flatworm with a very extraordinary way of reproducing. Image credit: Lukas Schärer

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. Continue reading “These flatworms plunge their penises into their own heads to inject themselves with sperm (when they must).”

One Chameleon, Eleven Chameleons: Genetics Reveal Cryptic Species in Madagascar’s Panther Chameleon

Perhaps the most common way that we tell different species apart is by looks. Different colors often mean deep-rooted differences, but in some species, color is a fluid concept. Take the chameleons: though it’s a myth that they can match any color they see around them, they are able to modify the patterns on their bodies to blend in, and some are known for dizzying color changes that are used as social signals — a colorful way of communicating with the chameleons around them.

The panther chameleon, Furcifer pardalis, is particularly well known for its vibrant beauty. These lizards are popular in the pet trade, where color ‘morphs’ or ‘locales’ are seen — the rarest highly coveted. These distinct looks are often named after Malagasy villages or islands where such colors are found. The Nosy Be morph is stunningly blue, like the chameleons found in that area, while the Sambava morphs are more mottled with green and yellow. On top of such stark geographic color differences, these little lizards also vary with season, age and mood (related: scientists make chameleon-mimicking material)

The highly variable colors of Furcifer pardalis. — The highly variable colors of *Furcifer pardalis*. Photo credits; left: Emmanuel Broeks, middle: Marc Staub, right: Tambako the Jaguar.

Continue reading “One Chameleon, Eleven Chameleons: Genetics Reveal Cryptic Species in Madagascar’s Panther Chameleon”

Mysterious Islands Are A Hotspot For Marine Hybrids

The Socotran landscape dominated by dragon's blood trees. Photo by Tane Sinclair-Taylor. — The Socotran landscape dominated by dragon’s blood trees. Photo by Tane Sinclair-Taylor.

Some 150 miles off the eastern coast of northern Africa — about 240 miles south of the Arabian peninsula — lies a set of islands that some have called “the most alien-looking place on Earth.” Socotra, which is both the name of the archipelago and the largest island, is a truly bizarre place. More than a third of the plants that erupt from the soil are found nowhere else. Their odd shapes and forms give the islands a Dr. Seussian quality, an almost cartoonish, comical landscape that stands in sharp contrast to the strict religious practices of the people who live there.

Socotra is a part of Yemen, a country currently engaged in a brutal civil war. But, it is also an island apart; the hundreds of miles of water that separate Socotra from the mainland have not only allowed biodiversity to take otherworldly forms, they have also allowed the people of Socotra to become distinct. The 50,000 or so people that live on the islands have their own language, myths and legends, and are their own governorate. Socotra has an archeological history that dates back to some of the earliest civilizations, complete with inexplicable cave art and 2,000 year old tools. The rich culture of the indigenous Soqotri has been insulated, like the flora and fauna they live alongside, for thousands of years — until the past decade, or so, when the Yemeni government has begun to open the islands to tourism.

In 2008, the United Nations Educational, Scientific and Cultural Organization (UNESCO) declared the islands a world heritage site, citing the incredible uniqueness and diversity of the land’s plants and animals — the “Galápagos of the Indian Ocean.” In addition to the hundreds of endemic plants, more than 90 percent of the reptiles and land snails that live on the islands are exclusive to them. Culturally and ecologically, Socotra is a place where uniqueness flourishes.

But the uniqueness of Socotra doesn’t end at the waters’ edge. Scientists have found that its coral reefs are pretty special, too — they’re home to a heap of hybrids. Continue reading “Mysterious Islands Are A Hotspot For Marine Hybrids”

More Bad News About The Lionfish Invasion (Happy Earth Day?)

Lionfish I helped catch off the coast of Beaufort, NC in 2013. Photo by Christie Wilcox. — Lionfish I helped catch off the coast of Beaufort, NC in 2013. Photo by Christie Wilcox

As I’ve described before, the Indo-Pacific lionfish in the Atlantic and Caribbean are quite possibly the worst marine invasion ever. These toxic predators have been eating their way around for the past few decades, driving down populations of native species and threatening already-struggling habitats. Now, a pair of papers released this month have more bad news: the lionfish are continuing to spread, and they may be eating the very last of critically endangered species.

Continue reading “More Bad News About The Lionfish Invasion (Happy Earth Day?)”

Smells Like A Boy: Lemurs May Use Scent of Mother to Determine Baby’s Sex

A long time ago, the great-great-great ancestors of humans and our relatives began to invest heavily in eyes. Sure, we have other senses — hearing, taste, touch — but primates excel at sight. There are lots of hypotheses to explain why eyesight was so evolutionarily valuable, from finding food to reading faces. But whatever the reason, vision became dominant, while other senses were left to languish, including our sense of smell. Primate olfaction is thought to be so miserable that scientists diminutively refer to our noses as “microsmatic” as opposed to the “macrosmatic” noses of dogs or rodents.

But the more we study the noses of our kin, the more we realize how important scent is to primates. Our closest cousins — the monkeys and apes in the Haplorhini (which refers to the to dryness of our noses) — possess similar sniffers to us, but as you move away from our supposedly feeble-nared lineage, our relatives become better and better smellers. Our most distant primate cousins, the lemurs and other ‘wet-nosed’ primates (Strepsirrhini), have a heightened, almost un-primate-like sense of smell, and recently, scientists have come to appreciate just how much they may rely on information obtained by their noses.

Lemurs use scents to tell who’s who, mark territories, and send important signals about their health or social status. Lemur sex lives, especially, are very smelly. Lemurs can tell whether a given secretion comes from a male or a female, and if female, whether she’s ready to make babies. Forget putting a female lemur on birth control — males will smell the difference, and lose interest.

Now, scientists have discovered that not only does smell come into play before pregnancy, lemurs emit particular scents when they’re expecting. These pregnancy odors are so unique that they can even be used to distinguish if the baby-to-be is a boy or a girl. Continue reading “Smells Like A Boy: Lemurs May Use Scent of Mother to Determine Baby’s Sex”

Biological Warfare: Parasitic Wasp Uses A Virus To Control Its Host

Any depth of understanding of biology and ecology is accompanied by this inevitable conclusion: parasites rule the world.

They’re the “man behind the curtain” as fans of Oz would put it. They are the directors and stage managers of the grand production that is life on this Earth, nature’s finest puppeteers, and that we think we have any modicum of control over any species’ physiology in comparison (including our own) is downright laughable.

The latest reminder of our inadequacy when it comes to manipulating biology comes from a fresh paper in Proceedings of the Royal Society B. In it, scientists describe how the parasitoid wasp, Dinocampus coccinellae, is able to manipulate its host, the ladybug Coleomegilla maculata: it uses another parasite, a never-before seen RNA virus.

A ladybug defending the cocooned parasite that emerged from it. Photo by BeatWalker from Wikimedia Commons — A ladybug defending the cocooned parasite that emerged from it.
Photo by BeatWalker from Wikimedia Commons

Continue reading “Biological Warfare: Parasitic Wasp Uses A Virus To Control Its Host”

A Toxic Relationship: Pufferfish Moms Poison Their Young (In A Good Way)

Life as a fish larva is tough.

Your odds of survival are slim to none. First off, you can’t swim all that well, so you’re mostly-drifting around in the ocean hoping that, when it’s time for you to settle down, you find yourself somewhere suitable. You’re also really, really small — the perfect morsel for tons of other species, from jellies to krill and even other fish. And your parents? They just abandoned you, sent you and your hundreds of siblings into the harsh real world without giving you anything to help you survive.

Unless you’re a larval pufferfish, that is. Your mom and dad may not win any parenting awards, but they didn’t leave you with absolutely nothing. Your mom did something that would make other reef fish larvae incredibly jealous, and that just might save your life: she gave you poison.

Continue reading “A Toxic Relationship: Pufferfish Moms Poison Their Young (In A Good Way)”