WEIRD HOUSES
Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.
Well, it was a close race between the medical and animal files this week in the “Most Bulging” category, but the animals won so off we go for yet another look at the wonderful animals that share (or have shared) our planet with us. It turns out that this week we’re concentrating on animal lifestyles. Of course, you may not want to look at our first animals. They may not win the “Ugliest Animal” contest, but they certainly are contenders!
THEY MAY BE NAKED BUT . . . .
Small rodents called naked mole rats are not only contenders for the ugliest animals, they rank right up there for “Weirdest Mammalian Life Style”. Apparently, they have forgotten they’re mammals and think they’re insects.
They’re found in the wild only in the Horn of Africa and they live underground in large colonies with tunnels that can stretch for miles. And the bee or wasp analogy doesn’t stop there; mole rats have a complicated social structure that includes a queen, her breeding males and two kinds of workers. Sound familiar? The workers are sterile and come in two sizes. The smaller ones find food and the larger ones defend the colony against attack.
They’re well adapted to life underground; they’re virtually blind and they’re hairless (saves combing the dirt out of the fur!). They also have really ugly rodent front teeth that they don’t bother to hide. So, why should we be interested in something this weird and this ugly?
Well, your common field or house mouse and most other small rodents typically live around two or three years but these bad boys have an average life span of about thirty years which is exceptionally long for a small rodent. There’s been a great deal of scientific interest in them because of their bizarre social structures and there are mole rat colonies in several major animal research centers.
And here’s what else they’ve discovered. Despite the large numbers of naked mole rats under observation, there has never been a single recorded case of a mole rat contracting cancer. And if that weren’t strange enough, mole rats appear to age very little until the very end of their lives.
Biologists at the University of Rochester think they may have discovered why naked mole rats don’t get cancer. They have a gene called p16 that makes their cells "claustrophobic." It stops the cells from reproducing when too many of them crowd together and this, of course cuts off runaway growth before it can start. The effect of p16 is so pronounced that when researchers mutated the cells to induce a tumor, the cells’ growth barely changed, whereas regular mouse cells became fully cancerous.
Vera Gorbunova, associate professor of biology at the University of Rochester and lead investigator on the discovery says, "It’s very early to speculate about the implications, but if the effect of p16 can be simulated in humans we might have a way to halt cancer before it starts."
When Gorbunova and her team began to investigate mole rat cells, they were surprised at how difficult it was to grow them in the lab for study. The cells simply refused to replicate once a certain number of them occupied a space. Other cells, such as human cells, also stop reproducing when their populations become too dense, but the mole rat cells were reaching their limit much earlier than the cells of other animals.
"Since cancer is basically runaway cell replication, we realized that whatever was doing this was probably the same thing that prevented cancer from ever getting started in the mole rats," says Gorbunova.
Gorbunova and her research team are now planning to delve deeper into the mole rat’s genetics to see if their cancer resistance might be applicable to humans.
A face only a mother could love but they may be the key to winning the battle against cancer. (Credit: Image courtesy of University of Rochester)
And continuing our investigation into animals with strange and wonderful lifestyles, let’s leave the mammal that thinks it’s a social insect and move on to some real social insects.
GO STUDY THE ANT
I’ve actually been rather surprised during this prolonged dry season that my house hasn’t become the local oasis for every water-seeking ant in my neighborhood as was the case in years past. Ants are fascinating and there are many different kinds. There are the ones that I call ‘crazy blacks’ because they’re black and they run around all over the place and act crazy. When I lived in Thailand there were ants everywhere. I remember leaving the house one day and seeing a huge solid disc of ants on my outside wall. They were all going around in a circle and the disc was about two feet across.
There was also a colony that lived upstairs that kept repletes. Repletes are specialized ants that are carried to a water ring on your table by the other ants. Then, they drink the water until their abdomen swells to about a quarter inch across. Then the other ants carry them back to the colony and use them as water fountains.
Of course, the best Thailand ant story involves the three or four I found in my house that were well over an inch long. Apparently, they’re the world’s largest ant and I was quite happy that they only appeared one at a time.
You’ve probably noticed that there are ants that smell funny when you crush them, sort of like moldy fruit. They are called odorous ants (no surprise there) and researchers from Purdue University have recently discovered some strange things about them.
Odorous ants are small ants that are typically forest dwellers but the scientists have discovered that odorous house ant colonies become larger and much more complex when they move from forest to city. The ants live about 50 to a colony with one queen in forest settings but explode into supercolonies with more than 6 million workers and 50,000 queens in urban areas.
Odorous ants are native to the US but they are acting like an invasive species when they move to the big city. One researcher said "Native ants are not supposed to become invasive. We don’t know of any other native ants that are outcompeting other species of native ants like these."
In semi-natural areas that are a cross between forest and urban areas, like a park, they’ve observed colonies of about 500 workers with a single queen. They believe that as the ants get closer to urban areas they have easier access to food, shelter and other resources.
The ants have been observed in three different settings on and around the Purdue campus and you might expect if odorous house ants can multiply into complex colonies, other ants would do the same.
But the researchers found no evidence that other ants had adapted to new environments and evolved into larger groups as the odorous house ants have. It’s possible that odorous house ants are better adapted to city environments than other ant species or that they had somehow outcompeted or dominated other species.
The researchers would like to know the answers because they have implications on the mechanisms that allow other invasive species to prosper. Future studies on odorous house ants will include studying the ant’s genetics and trying to understand the effects of urbanization of odorous house ants.
Grzegorz Buczkowski discovered odorous house ants living in supercolonies, creating complex networks entomologists have never seen with the species before now. (Credit: Purdue Agricultural Communication photo/Tom Campbell)
And now we’ll segue into a tale about some animals in our own back yard. They aren’t generally considered social, but researchers have recently observed a behavior that will change how you look at them forever just like our recent tale of the ‘ride ‘em cowboy’ germ-fighting cell and its rope.
REAL ESTATE MADNESS
Everybody wants to live in the nicest possible house, right? And when you outgrow your house, you’d like a bigger one, right? Well, consider the dilemma of our old familiar friend, the hermit crab. He routinely outgrows his house and a recent study by biologists at Tufts University and the New England Aquarium shows us that hermit crabs have a bizarre and wonderful way to deal with the housing crisis. They shop together.
With their soft abdomens, hermit crabs that aren’t in some kind of shelter are food for somebody very quickly. We’ve all seen them dragging around cans and baby bottles and all sorts of weird and unsuitable ‘homes’ because there weren’t enough suitable shells to go around.
So, how do hermit crabs win this life-or-death shell game? By doing some overnight observing, the researchers discovered some really cool behaviors. They placed vacant shells on the beach and watched to see what would happen.
They discovered that when a hermit crab discovers an empty but oversized shell, it waits nearby instead of simply walking away. Once a small group of crabs gathers, they begin to ‘piggyback’ by holding onto the shell of a larger crab and riding along. These waiting and piggybacking behaviors seem to increase the chances that something truly wonderful will happen.
Scientists call it a synchronous vacancy chain. What it means is that when a new large shell becomes available, the hermit crabs gather around it and form a line from the largest to the smallest. What happens next is really good.
Once the largest crab moves into the new vacant shell, each crab in the line sheds its old shell and immediately plops into the newly vacated shell right in front of it. As a result, a single vacant shell kicks off an entire chain of shell vacancies that ultimately leads to everybody in the line getting new, larger and generally improved housing.
So, the next time you’re at the beach, watch the hermit crabs for a while and then imagine what happens when they go house-hunting tonight!
A hermit crab investigating a potential new shell house. Hermit crabs may locate new and improved housing using previously unknown social networking skills. (Credit: Image courtesy of Tufts University)
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