Animal That Survives in Space Has Weird DNA
Wyss Institute at Harvard University
This week we learned about asea mollusk
that, among other attributes, has hundreds of eyes. (It might look like an alien landscape, but this photo shows some of those eyes.) That's a lot of eyes. And it got us thinking about animal eyes, and how varied, expressive, and just plain neat they can be. So here are some eyes we think are noteworthy, on their looks alone. Enjoy.Weird Sea Mollusk Has Hundreds Of Eyes Made Of Armor
Deer flies have stunners for eyes. Careful getting too close, though: they can bite with vengeance.Faces Of Bees, Flies And Friends: Photos
How can you top the mantis shrimp for orbital razzle-dazzle? In addition to its flair, the creature has a highly complex visual system. Thanks to 16 types of color-receptive cones, it can see many more colors than other animals.Natural Sunscreen Explains Mantis Shrimp's Amazing UV Vision
We're not letting you off the hook without having to look at a spider. Sorry, arachnophobes! Jumping spiders can see with three different sets of eyes. Wide-angle side eyes detect distant movement; two large eyes on the head extend to provide telephoto vision for tracking prey, and four additional side eyes observe movement all around them.Giant Spiders To Freak You Out: Photos
Just to appreciate the scale, we're showing you a giant squid's eye, detached, sadly, from its former owner. Giant squid have the largest eyes in the world, according to the Smithsonian National Museum of Natural History.Giant Squid Photos
If eyes are the windows to the soul, do we really want to know what's going on inside this rough knob-tailed gecko (
)? Let's ask it. But, you go first... While most species of gecko can't blink, they're able to clean and moisten their eyes by licking them.Gecko Skin Is Surprisingly Un-Sticky
Centris bees, like so many others of its buzzzzing brethren, have unforgettable eyes. Big, scary style points for this one.Video: Why Are All The Bees Dying?
The huge, wide eyes of the Philippine tarsier are real attention-grabbers -- the highest eye-to-body-size ratio seen in mammals. Its outsized eyes give the tiny primate fantastic vision at night. But, there's a catch -- the eyes are fixed in their sockets, no movement allowed. Thankfully, there's a counter to the catch: The plucky primate can rotate its head 180 degrees.Funniest-Faced Monkeys: Photos
was coming, didn't you? It doesn't matter what species you choose, owl eyes are beyond striking. This owl has had perhaps a bit too much caffeine.How Owls Turn Heads -- Their Own
Red-eyed tree frogs (
) start out life with yellow eyes when they're tadpoles. But eventually the tomato-red look kicks in. It uses its fiery eyes to try to shock potential predators into freezing up just long enough for the little peeper to escape.7 New Teeny Frogs Found In Brazil: Photos
The only animal known to survive the extreme environment of outer space without the help of special equipment turns out to have the most foreign DNA of any species.
Water bears, also known as tardigrades, have genomes that are nearly one-sixth foreign, meaning that the DNA comes from creatures other than the animal itself, new research finds.
The discovery, published in the Proceeding of the National Academy of Sciences, adds to the evidence that tiny water bears are incredibly unique and seemingly indestructible animals. In 2007, some were even rocketed into space on the outside of a satellite.
When the satellite returned, many of the water bears were still alive. What’s more, some of the females had laid eggs in space, with the young hatching healthily, as though nothing had happened.
“We had no idea that an animal genome could be composed of so much foreign DNA,” co-author Bob Goldstein of the University of North Carolina at Chapel Hill said in a press release. “We knew many animals acquire foreign genes, but we had no idea that it happens to this degree.”
Water bears are segmented, eight-legged micro-animals that measure just a miniscule fraction of an inch long. Goldstein, lead author Thomas Boothby and their team determined that water bears acquire 6,000 foreign genes primarily from bacteria, but also from plants, fungi and various single-celled microorganisms.
This means that 17.5 percent of the water bear’s genome comes from these other sources.
The DNA is acquired via a process called horizontal gene transfer. Instead of just inheriting DNA, it is swapped between species.
Boothby said, “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.”
Water bears have astounded scientists for years with their heartiness. For example, you can stick them in a freezer for a year. Within 20 minutes, the animal thaws out and starts to scurry around as normal.
The researchers suspect that when water bears are under conditions of extreme stress, such as desiccation, their DNA will break into small pieces. When the cell rehydrates, the cell’s membrane and nucleus (where the DNA resides) become temporarily “leaky,” such that DNA and other large molecules can pass through easily.
During this process, the water bears not only repair their own damaged DNA, but also stitch in the foreign DNA, creating a mosaic of genes that come from different species.
The prior record holder for most foreign DNA was another microscopic animal called the rotifer. It is now known that rotifers just have about half as much foreign DNA as water bears, though.
The human genome also has such foreign DNA. It’s been estimated that about 8 percent of our DNA comes from retroviruses. HIV is a type of retrovirus. That refers to a virus whose RNA codes for DNA, which is then inserted into some part of the host’s DNA.
“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 and the stability of genomes,” Boothby said.
“So instead of thinking of the tree of life, we can think about the web of life and genetic material crossing from branch to branch. So it’s exciting. We are beginning to adjust our understanding of how evolution works.”
Photo: A tardigrade, also known as a “water bear.” Credit: Sinclair Stammers