Tardigrade sex: cover your eyes

Although some species are parthenogenic, both males and females are usually present, each with a single gonad located above the intestine. Two ducts run from the testis in males, opening through a single pore in front of the anus. In contrast, females have a single duct opening either just above the anus or directly into the rectum, which thus forms a cloaca.[24]

Tardigrades are oviparous, and fertilization is usually external. Mating occurs during the molt with the eggs being laid inside the shed cuticle of the female and then covered with sperm. A few species have internal fertilization, with mating occurring before the female fully sheds her cuticle. In most cases, the eggs are left inside the shed cuticle to develop, but some species attach them to nearby substrate.[24]

The eggs hatch after no more than 14 days, with the young already possessing their full complement of adult cells. Growth to the adult size therefore occurs by enlargement of the individual cells (hypertrophy), rather than by cell division. Tardigrades may molt up to 12 times.[24]

Tardigrades: the horror

I had no idea, when I began to probe the subject of tardigrades, how quickly I'd be in over my head. Soon I felt I was trapped in some sort of ceaseless pageant of unnameable, formless horror.

As it turns out, tardigrades don't just live in stagnant mudpuddles, National Geographic specials on microbiology or Wikipedia entries that go on forever. They have invaded the culture. Here I hadn't even heard of them, and now they are seemingly everywhere, especially in DeviantArt. The artist didn't have to exaggerate very much to create this frightening gangsta 'grade.


 

And this. What is this? The General Patton of tardigrades?

It gets a bit ridiculous, but yes, there are Tardy (or Grade, whichever you prefer) stuffies. This one is named Tardy O'Grady.

This looks like a twisted loaf of garlic bread to me, but it's a 3D printed copy of a tardigrade. Believe me, there were much worse things floating around the internet, including tardigrade jewelry (wtf???) and crochet patterns to Make your own Grade.

And you can keep them as pets, too! Approximately 350 tardigrades to one drop of water.

Tardigrades: the terror

From Charlie Nadler's blog:

Tardigrades are harmless.

Fiction. While most of us will probably never be personally assaulted by a tardigrade, this does not mean that they are harmless. In fact, their very existence is deeply detrimental to our mental health. We understand that there’s virtually no escape from these water bears; they’re hiding beneath the ice in the Arctic Ocean, at the top of the Himalayas, in our backyards, and everywhere in between. Even if we can’t see them, we can feel their presence and sense that they are awaiting our demise. Their silence is deafening.

As humans, we struggle to cope with this dark reality; the long, sinister shadow cast by tardigrades shapes our identities and prevents us from forming “healthy relationships” with other people. We often find ourselves unable to sleep, our minds victims of the night as they become caught in infinite water bear thought-loops. In our moments of weakness, we can’t help but wonder: What if there was a pill or an elixir we could take that would transform us from human to tardigrade? Would we consider taking such a thing? Perhaps, if we did take it, we would realize that we have in fact been living a lie; that, all along, we were actually tardigrades trapped in human bodies. Once corrected to our true form, we would command respect from our fellow tardigrades and be elected to a prestigious position with much responsibility. The important work we’d accomplish would earn admiration from our peers and maybe even the love of a beautiful female water bear with whom we could settle down and start a family. Our parents would finally see that we aren’t the disappointments they always thought we were. For the first time in our lives, we’d feel accepted, appreciated, and loved.

Those wacky little creatures: TARDIGRADES!

The tardigrade genome has been sequenced, and it has the most foreign DNA of any animal

Water bears just got even weirder.

FIONA MACDONALD

25 NOV 2015

Scientists have sequenced the entire genome of the tardigrade, AKA the water bear, for the first time. And it turns out that this weird little creature has the most foreign genes of any animal studied so far – or to put it another way, roughly one-sixth of the tardigrade's genome was stolen from other species. We have to admit, we're kinda not surprised.

A little background here for those who aren’t familiar with the strangeness that is the tardigrade – the microscopic water creature grows to just over 1 mm on average, and is the only animal that can survive in the harsh environment of space. It can also withstand temperatures from just above absolute zero to well above the boiling point of water, can cope with ridiculous amounts of pressure and radiation, and can live for more than 10 years without food or water. Basically, it's nearly impossible to kill, and now scientists have shown that its DNA is just as bizarre as it is.

So what's foreign DNA and why does it matter that tardigrades have so much of it? The term refers to genes that have come from another organism via a process known as horizontal gene transfer, as opposed to being passed down through traditional reproduction.

Horizontal gene transfer occurs in humans and other animals occasionally, usually as a result of gene swapping with viruses, but to put it into perspective, most animals have less than 1 percent of their genome made up of foreign DNA. Before this, the rotifer – another microscopic water creature – was believed to have the most foreign genes of any animal, with 8 or 9 percent.

But the new research has shown that approximately 6,000 of the tardigrade’s genes come from foreign species, which equates to around 17.5 percent.

“We had no idea that an animal genome could be composed of so much foreign DNA,” said study co-author Bob Goldstein, from the University of North Carolina at Chapel Hill. “We knew many animals acquire foreign genes, but we had no idea that it happens to this degree.”

So where is the tardigrade getting all its genes from? The foreign DNA comes primarily from bacteria, but also from plants, fungi, and Archaea. And it’s this incredible variety of genes that researchers suggest has allowed the water bear to survive in such extreme conditions. 

“Animals that can survive extreme stresses may be particularly prone to acquiring foreign genes – and bacterial genes might be better able to withstand stresses than animal ones,” said one of the researchers, Thomas  Boothby.

The team hasn't investigated exactly how this gene-stealing is happening just yet, but they propose that it's a result of one of the tardigrade's other crazy survival mechanisms – the ability to dry out until its body is less than 3 percent water, and then come bounce back once they're rehydrated.

When this desiccation happens, scientists know that their DNA breaks down into tiny pieces. They also know that when their cells rehydrate, there's a point in time when the cell nucleus is leaky, allowing DNA and other molecules to pass through. That means that while the tardigrade is quickly patching up its own genome, it may accidentally be stitching in another organism's genes.

This would be a random process, but the genes that get passed down would be those that help the animals survive. Further research now needs to be done into exactly how tardigrades are obtaining this foreign DNA, and how often it’s happening. But what’s really exciting is that it provides new insight into exactly how life evolves.

“We think of the tree of life, with genetic material passing vertically from mom and dad. But with horizontal gene transfer becoming more widely accepted and more well known, at least in certain organisms, it is beginning to change the way we think about evolution and inheritance of genetic material,” said Boothby. “Instead of thinking of the tree of life, we can think about the web of life and genetic material crossing from branch to branch ... it’s exciting. We are beginning to adjust our understanding of how evolution works.”

The research, which has been published in PNAS, could also provide some insight into useful genes we could use in medicine and drug development. So long live the water bear, in all its weirdness.

Read these next:

·                     New water bear species discovered in Antarctica

·                     The DNA of a boy sacrificed by the Inca suggests a lost, ancient lineage

·                     Ancient DNA reveals how agriculture changed our height, digestion, and skin colour

  Visit Margaret's Amazon Author Page!

http://www.amazon.com/-/e/B001K7NGDA

Tardigrade gif

Tardigrade!

No, this is not a vacuum-cleaner bag from an ancient upright Hoover.

It is not a frightening Halloween costume made out of old army tents.

It is not a hazmat suit for an armadillo.

It is not a - uh - um.  I hope it's fake because if it's real, I will be having trouble sleeping.

But no. This is called a tardigrade and it is real. I have a whole lot of information on it and even a gif, none of which will post right now. Maybe not this, either.