Sunday, October 24, 2010

Talking Up Serpents

I was speed-walking distractedly down a ridgetop in Briones Park, pumping my arms and kicking up dirt. The light was long past golden, and I was determined to get back to my car before sundown, when the bobcats, coyotes and mountain lions come out. My mini-back pack was starting to dig into my shoulders, and as I stopped to adjust the straps, I noticed something long and white flapping in the brush. I crouched down to get a closer look. Draped over a shrub was a discarded snake skin, paper thin and rustling in the wind. It had obviously been shed by a rattler of impressive proportions. The head and tail end were missing, but the skin was still over a foot long and maybe one and half inches wide. I picked it up for a closer look. I could see the fishnet pattern of the snake's back scales, and the parallel ridges that had once girded its belly.

I tucked what appeared to be the least fragile end of my find into the back pocket of my daypack and resumed walking, the snakeskin flapping behind me like a banner. A couple of hikers were coming down the dip in the path ahead, towards me. Of course, I had to ask if they would like to see my snakeskin - an invitation that, were I a man, could have made me sound like what my daughter calls "a huge perv". But I am an eccentric middle aged lady, and if they thought I was insane, they did a good job of hiding it. They paused for a quick look - I think they were impressed.

I had seen rattlesnakes at Briones a couple of times before. Now, I watch my step. Especially since I broke my distance glasses about six months ago and have a tendency to confuse cow pies with coiled serpents. (One smells, the other hisses). But I made it safely back to my car. Despite its fragile appearance, the skin held up quite well and currently adorns my office bulletin board.

Once I had done a little research, I was less impressed with myself for finding that snakeskin. It seems rattlers molt three or four times a year, depending on how well-fed they are (strictly a function of the size of the rodent population). Out of 16 varieties of rattlesnake indigenous to the United States, a grand total of ten can be found in California. It is likely that my souvenir was shed by the redundantly named Crotalus oreganus oreganus, or Northern Pacific Rattlesnake. And now, a few fast facts about rattlesnakes:

They are easily identifiable. That signature tail is just one of the rattlesnake's distinguishing characteristics. Rattlers have thicker bodies than most snakes and triangular-shaped heads with a distinct “neck”. Their lidless eyes are hooded, with elliptical pupils. Don't get close enough look into them or you might discover that rattlesnakes strike at a speed faster than the human eye can process! While rattlers have much better night vision than we do, they are profoundly deaf. However, they are exquisitely sensitive to vibrations, such as those caused by your approaching footsteps.

They give birth to live young. Yes, I realize the photo is about as gross as the extra-terrestrial hatchery uncovered by Sigourney Weaver in Alien 2. No, I did not take this picture: I would have dropped my camera and run screaming from the room. Rattlers are ovoviparous, which means that their eggs hatch inside the mother's body and the young are born live. The 10-inch long snakelets are already venomous at birth, living proof that not all baby animals are cute. These babies won't get their first rattle until their first molt, roughly ten days after they are born. They compensate by being more aggressive than their elders. Fortunately for us hikers, many rattlesnake young are gobbled up by hawks, eagles, badgers, or coyotes.

They add on a rattle every time they shed. However, the rattles eventually break off, and it's rare to see more than ten of them on a single snake. The notion that you can tell a snake's age by the number of rattles on its tail is simply not true – rattlers can live for as long as thirty years, but you never see one with thirty rattles. The rattles consist of keratin "beads" of hardened skin around the snake's tail. When the serpent shakes its rear, the beads bump against each other and make that signature warning sound.

If you see this florid organ on a rattlesnake, it means he's glad to see you.

They have strange body parts. Rattlesnakes are pit vipers. This term refers to a pair of openings, called loreal pits, located on the sides of their heads. Loreal pits are an infrared sensing device, enabling the snake to sense the temperature difference between the cool night air and a nice, fat chipmunk. (Remember the alien's heat-seeking vision in Predator with Arnold Schwarzeneger? Same concept). Snakes, including rattlers, don't smell with their snouts. They flick their tongues in and out to sample odors in the atmosphere. Inside their mouths is the "Jabobsen's organ", which relays smell information from the tongue to the brain. The forked tongue is a directional aid that lets the snake know whether those tempting field mouse pheromones are wafting from the left or the right. The lucky male rattlesnake has two penises (or is that penii?), called hemipenes. (The bad news is he's hung like a sea anemone - see photo above). He only uses one hemipene at a time, and both remain inverted inside his body until it's time to get busy.

They have retractable teeth. If a rattler is busy sunning itself while digesting some hapless quail, its fangs lie flat inside its mouth. But when it gets ready to strike, they rotate downward 90 degrees, into stabbing position. Like little hypodermic needles, the snake's hollow fangs inject venom into its prey. Designed to fall out and grow back several times a year, the fangs break off easily, sometimes getting swallowed right along with dinner. The snake's hinged jaw can literally drop out of its socket, enabling it to swallow prey as large as a cottontail rabbit.

Slumber party!

They take the winter off. Rattlesnakes hibernate from November to April, usually in large groups. They like rocks or rodent burrows but have been known to camp out in the basements of buildings. In the summer, they spend their days chilling under rocks and shrubs. Hunting happens at night, with the help of those heat-seaking Jacobsen's organs.

Their bite rarely kills a healthy adult human. Rattlesnakes can actually regulate the amount of venom they release. They may bite "dry" in self-defense - why waste perfectly good venom on something that's too big to eat? If you do get a shot of venom, you could be in big trouble. The poison disrupts blood clotting and destroys tissue. Even with prompt treatment, scarring is inevitable. Read about 13 year old Justin's snake bite and look at the hideous photos of his surgery, if you dare. (I'm actually sorry I looked - the poor kid's arm looks like a detail from an anatomical drawing of a flayed man.)

Which brings us back to shedding. Rattlesnakes slip out of their outgrown epidermis as soon as they emerge from hibernation, and they shed two or three additional times each year. The snake rubs its nose against a rock or branch until it creates a big enough tear to start slipping out of his skin, which turns inside out in the process. It would be nice if people could do the same - simply shed our exterior when it starts to cramp our style. Wriggle out of our past. Grow a new skin. Of course, any human who can pull this off is probably already a snake.

More fun with Northern California fauna:

elephant seals
clown perverts

P.S. Happy Halloween!

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