Do you see what it's eating?: Fingers.
Courtesy lavendarladyThere’s big trouble in Little America (that’s what all the cool kids are calling England these days, that or “Olde America”).
It seems that Cambridge, Little America, is being invaded by black squirrels.
“Why is this a big deal?” you ask. I’ll tell you why. First of all, you have to keep in mind that most large, dangerous animals were hunted to extinction in England hundreds of years ago. So, while we North Americans are used to bears, wolves, mountain lions and cheetahs wandering our streets, it has been centuries since most Brits have had to deal with anything more dangerous that, say, a bunny. Squirrels, while often smaller than bunnies, can be slightly more dangerous—if necessary, a bunny can usually be avoided by going up stairs, or standing on a chair, but this won’t work for squirrels. The squirrel is, after all, nature’s monkey.
But it’s not the presence of squirrels alone that’s dangerous here. Cambridge had squirrels before, but these new squirrels are mutants. Mutant, melanistic, black-furred gray squirrels, and they are slowly but surely running the old-fashioned gray squirrels out of town.
Melanism, simply, is a genetic variation that causes skin, fur, or feathers to be consistently dark. It’s sort of the opposite of albinism. Black panthers, for instance, are just melanistic leopards or jaguars. Melanism is usually fairly uncommon in animals—if a species has evolved its fur or feathers to be camouflage within its natural environment, a melanistic individual might end up sticking out like a sore thumb and getting eaten before it can pass on its genes. This sort of selective pressure is probably less significant for your average city squirrel, and having black fur may not necessarily be detrimental, and other traits could determine a species’ success.
Red squirrels used to be common in Olde America, for instance, until the introduction of larger, more aggressive gray squirrel. Now red squirrels are largely extinct in Britain, except for certain small pockets in Scotland, forced out by the brutal gray squirrel armies. Oh, wait, something perfect just happened.
Right, so now the same thing is happening to the gray squirrels. There’s some evidence that in large cats melanism offers a certain amount of protection from viral infection, so it could be that the new melanistic squirrel population receives similar genetic benefits. It has also been suggested, though not yet proven, that the melanistic squirrels are more aggressive than their gray cousins due to higher testosterone levels.
Also, I just dug this link up the other day, but it seems appropriate here too. In Russia a couple years ago, there was a report of a pack of black squirrels killing and eating a big stray dog. A choice quote:
"They literally gutted the dog," local journalist Anastasia Trubitsina told Komsomolskaya Pravda newspaper. "When they saw the men, they scattered in different directions, taking pieces of their kill away with them."
In short, it may be that Little America’s days are now numbered. Consider canceling vacation plans, or at least packing squirrel repellent.
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Albino or not?: Is this an ablino squirrel or just a white variety of a regular squirrel. Check out the eyes to find out.Have I been working too hard lately, or was that a white squirrel I just saw?
The past couple weeks I’ve seen more white squirrels than I’ve ever see before and I was all excited that I was finding rare albino versions of the animal. After poking around on the Internet, however, I’ve discovered there’s a lot more to this than meets my eyes.
Thanks to information I found on the Minnesota Department of Natural Resources website, just because an animal is white (when it normally isn’t that color) doesn’t mean that it’s an albino. Conversely, an albino animal doesn’t have to be totally white, either.
The answers can all be found in the animal’s genes. Animals that have strong white coloration lack the genetics to produce the pigment melanin.
An albino member of a species inherits genes that interrupt the making of melanin. But other members of the same species may have other factors that block melanin production, making the animal look all white. The key difference can be found in the eyes.
An albino will have pink or light blue eyes, shades that are very uncommon to the animal. A white, non-albino will have eyes that are usual color of its species, usually black. From what I’ve seen lately, the white squirrels I’ve been seeing have black eyes. The estimated rate of albinism in squirrels is estimated at one in 100,000.
Of course, there are some other all white mammals. They’re called leucistic. Polar bears are leucistic year round, while snowshoe hares have a leucistic phase in the white, giving them good cover in the winter snows.
Getting back to the white squirrels, there are a number of towns across North America that celebrate their white furry critter. For instance, in Olney, Illinois, protects and fosters their growth. They’ve had laws on the books to protect the white rodents since 1902 and had a population that grew to 1,000 at one time. Today, there are about 200. Olney, along with towns in North Carolina, California, Texas and Ontario, use the white squirrels as tourist attractions.
The book is still out on if albinism is a detriment to survival. On first thought, being all-white would be a huge disadvantage to being spotted by a predator, you might think. But through more study naturalists have come to believe predators may not recognize a white-version of their prey as food. In studying albino birds, researchers have found that the white-feathered creatures have a hard time finding a mate -- another reason why the albino genes become so rare.
Is this an ablino squirrel or just a white variety of a regular squirrel. Check out the eyes to find out.
Please contact us if you have questions about the rights on this image.
Sunbathers: Soaking up the sun in the California desert. Courtesy Mark Ryan.
Here’s a question for the start of summer: why does exposure to the sun darken our skin but lighten our hair?
First let’s take a look at our skin. Human skin is the body’s largest organ, and acts as a barrier between our inner organs and the outside world. It’s made up of essentially two parts the epidermis and the dermis. The epidermis is the outer section and is comprised of a layer of living cells, topped by a layer of dead cells. The dead cells are the skin we see.
Even though the upper epidermis is just a lot of dead cells, it contains keratin, a tough protein that also makes up our hair and fingernails, Keratin is thicker on the bottoms of our feet and the palms of our hands for added protection against abrasions and other intrusions from the outside world.
Inside the dermis is where all the skin’s functioning equipment is located, These include nerves, sweat glands, hair follicles, blood vessels and special cells called melanocytes, which produce melanin, the material responsible for skin pigmentation, hair and eye color. Most humans have about the same amount of melanocytes, some just produce more melanin than others. Albinos, however, produce no melanin at all.
When our skin gets exposed to sunlight (particularly ultraviolet rays) melanocytes begin producing melanin to help protect the dermis, and keep the skin cells from getting fried. The melanin acts as an absorbing agent. So over time, as exposure to the sun continues, more melanin is produced and subsequently the skin becomes darker.
The hair is a different story. Hair color is also determined by melanin, but hair cells are dead, so sunlight doesn’t initiate melanin production but rather begins to break down the melanin already in the hair, and the hair’s color begins to fade or lighten.
Sunglasses may not be so cool: Courtesy Mark Ryan
I thought this last part was strange. The pituitary gland is tied to your optic nerve and is sensitive to sunlight. When light enters your eyes, it triggers your pituitary gland to produce a melanocyte-stimulating hormone (MSH) that activates your melanocytes to produce melanin. This means that wearing sunglasses can actually cause sunburn.
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