Toxodon. Illustration by Peter Schouten from the forthcoming book “Biggest, Fiercest, Strangest” W. Norton Publishers (in production)
“Toxodon is perhaps one of the strangest animals ever discovered,” wrote Charles Darwin, a man who was no stranger to strangeness.
He first encountered the creature in Uruguay on November 26th, 1834.
“Having heard of some giant’s bones at a neighbouring farm-house…, I rode there accompanied by my host, and purchased for the value of eighteen pence the head of the Toxodon,” he later wrote.
The beast’s skeleton, once fully assembled, was a baffling mish-mash of traits.
It was huge like a rhino, but it had the chiselling incisors of a rodent—its name means “arched tooth”—and the high-placed eyes and nostrils of a manatee or some other aquatic mammal.
“How wonderfully are the different orders, at present time so well separated, blended together in different points of the structure of the toxodon!” Darwin wrote.
Those conflicting traits have continued to confuse scientists. Hundreds of large hoofed mammals have since been found in South America, and they fall into some 280 genera.
Scientists still argue about when these mysterious beasts first evolved, whether they belong to one single group or several that evolved separately, and, mainly, which other mammals they were related too.
“That’s been difficult to address because they have features that they share with a lot of different groups from across the mammalian tree,” says Ian Barnes from the Natural History Museum in London. “To some degree, people have circled around the same set of evidence for 180 years.”
Now, Barnes’ team, including student Frido Welker from the Max Planck Institute for Evolutionary Anthropology and Ross MacPhee form the American Museum of Natural History, have found a way to break out of the circle.
They recovered a hardy protein called collagen from the fossil bones of Toxodon and Macrauchenia, another South American oddity that resembled a humpless camel. By comparing these molecules to those of modern mammals, the team concluded
“Toxodon looks a bit like a hippo and we now know that the features they share with hippos are probably due to convergence,” says Barnes. “Macrauchenia looks a bit like a camel, but we can now see that it’s not particularly well related to camels.. This has been a longstanding mystery and we have an answer, and that’s satisfying.”
The discovery has bigger implications, though. Many scientists, Barnes included, have recovered DNA from very old fossils. They have sequenced the full genomes of mammoths and Neanderthals, worked out the evolutionary relationships of giant birds, and even discovered entirely new groups of early humans.
But ancient DNA has its limits.
To fish it out of fossils, you need molecular bait, and to design that bait, it really helps to know what kind of animal you’re looking for and what they’re related to. If you don’t, and your only clue is “er, some kind of mammal”, then recovering ancient DNA is hard.
It becomes harder if the fossils are also very old, since DNA has a half-life of around 521 years.
And it becomes absurdly hard if the bones come from warm climates, like most of South America, where DNA degrades even faster than usual.
That giant claw is perfectly natural: The shrimp uses it to snap so hard that it briefly heats the water to 8,000 degrees Fahrenheit. Photo: Arthur Anker/Flickr
The greatest real-life gunslingers have to be the pistol shrimp, aka the snapping shrimp, hundreds of species with an enormous claw they use to fire bullets of bubbles at foes, knocking them out cold or even killing them.
The resulting sound is an incredible 210 decibels, far louder than an actual gunshot, which averages around 150.
Pound for pound, pistol shrimp are some of the most powerful, most raucous critters on Earth.
Yet at the same time they are quite vulnerable, allying with all manner of creatures and even forming bizarre societies to protect themselves from the many menaces of the ocean bottom.
The Life Despotic
The pistol shrimp has two claws, a small pincer and an enormous snapper. The snapper, which can grow to up to half the length of the shrimp’s body, does not have two symmetrical halves like the pincer.
Instead, half of it is immobile, called a propus, which has a socket.
The other half, called a dactyl, is the mobile part. It has a plunger that fits into this socket.
The shrimp opens the dactyl by co-contracting both an opener and closer muscle.
This builds tension until another closer muscle contracts, setting the whole thing off with incredible force.
An image taken with a microscope shows a cross section of the trap of a humped bladderwort (Utricularia gibba). Those spiky discs are friendly algae that hitch a ride inside. Photo: Igor Siwanowicz
We get a lot of press releases about photo contests, but this winning image from the Olympus BioScapes Imaging Competition (which I didn’t even know existed) stood out for a few reasons:
1. The image itself is really neat.
2. What’s actually happening in the image is also neat:
Apparently this is like a microscopic aquatic version of a Venus’ flytrap — it sucks little microinvertebrates into its trap a millisecond after they trigger its hairs.
3. It’s called a humped bladderwort, or Utricularia gibba if you wanna get technical. It’s a flowering plant that grows in ponds and lakes all over the world. (Earnest bladderwort explainer video.)
4. Speaking of technical, the process is interesting. According to press-release jargon, “Igor Siwanowicz, a neurobiologist at the Howard Hughes Medical Institute’s Janelia Farm Research Campus … magnified the plant 100 times using a laser scanning confocal microscope and used cellulose-binding fluorescent dye Calcofluor White to visualize the cell walls of the plant.”
Siwanowicz began photographing about 10 years ago, and has a much larger collection of similar images — which you won’t regret checking out.
Susan, your octopus got loose again!” A crew member delivered the news to photographer Susan Middleton late at night during a 2006 expedition in the French Frigate Shoals, the largest atoll in the North western Hawaiian Islands.
Middleton rushed to the wet lab where she had been photographing a day octopus alongside scientists collecting and listing marine invertebrates as part of the Census of Marine Life, a decade-long international collaboration (2000-2010) to assess the world’s ocean inhabitants.
Middleton knew she had tucked the octopus into a five-gallon bucket with a lid before she went to bed, but it had escaped twice. On its third breakaway, Middleton found it trying to make a run for the deck, its three-foot-long arms sticking to the floor, and its talent for changing color, pattern and texture no match for the linoleum.
The portrait that Middleton eventually captured of the octopus before putting it back in the sea is one of the 250 images she photographed for her new book, Spineless: Portraits of Marine Invertebrates, The Backbone of Life, published by Abrams.