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According to Rubio, "The most widely accepted hypothesis for the evolution of the rattle is that the rattle is a warning device for predatory animals that might be a threat to the rattlesnake. It produces a signal to drive them away."
The rattle is composed of a series of hollow, interlocked segments made of keratin, which are created by modifying the scales that cover the tip of the tail. The contraction of special "shaker" muscles in the tail causes these segments to vibrate against one another, making the rattling noise (which is amplified because the segments are hollow). The muscles that cause the rattle to shake are some of the fastest known, firing 50 times per second on average, sustained for up to three hours.
At birth, a “prebutton” is present at the tip of the snake's tail; it is replaced by the “button” several days later when the first skin is shed. However, no sound can be made by the rattle until a second segment is added when the skin is shed again. A new rattle segment is added each time the snake sheds its skin, and the snake may shed its skin several times a year, depending on food supply and growth rate.
Rattlesnakes travel with their rattles held up to protect them from damage, but in spite of this precaution, their day-to-day activities in the wild still cause them to regularly break off end segments. Because of this, the age of a rattlesnake is not related to the number of rattles on its tail.
One of the differentiating features of males and females is the males have thicker and longer tails (because they contain the inverted hemipenes). Also, the tails of males taper gradually from the body, whereas the tails of females narrow abruptly at the vent.
Just a thought here, but, no rattlesnake is a perfect, they don't all have rattles that we love to hear as a warning shot to jump, flight or fight. Predominately, the rattlesnakes that end up being hunted down, do have rattles. Evolutionary ????? elimination of the 'fittest' rattlesnakes will be replaced by the rattlesnake without a rattle.
No warning, more deaths, no flight, no fight.
Of course not all of the rattlesnakes with rattles will ever be hunted down to extinction, but evolution is a funny thing.....
2 comments:
Will the scientist(s) tagging the rattlesnake buttons with paint become skewed if a button falls off? What are the permutations for an eight button lotto?
My favourite snake was the big old fox snake lived under a field stone end of my Dad's laneway. We became accustomed to sunny greets when my kid brother and I'd walk home from our two-room (eight grades) schoolhouse just in the corner of our ten-acre front field and that fox snake'd be waiting (or so it seemed) on the top of that smooth rock in the afternoon sun.
Two things about a fox snake: first, it's North America's only native constrictor, strong enough to suffocate rabbits, mice and other small animals (our regular fun was to pick it up by the head---which it never seemed to mind---and take turns letting it wrap around our forearms and squeeze for all it was worth); second, fox snakes pretend to be rattlers by the way they coil up as if to strike, and "rattling" a rattle-less tail, often trying to russell dried leaves or grass for effect. They even have a diamond-back pattern but, put beside a real rattler (those our parents would encourage us kids to exterminate---five and eight-year-olds armed with sticks and stones---and occasionally fry-up to eat, real rattlers being fairly tasty), you can quickly see the difference between the two species: fox snakes are relatively sleek compared to the robust and somewhat hoary rattler.
And, of course, fox snakes have tiny, serrated teeth like a garter snake, and they are not venomous.
Only other thing one needs to know is that real rattlers can and do lose their rattles, a fact we tried to scare our neighbour's kid with by convincing him the fox snake was really a rattler. Don't know whether it was him or his father, but soon after we discovered our friend, mushed to death with another rock atop his (or her---we never saw a mate for several years) big smooth sunning rock. I still feel bad about that fox snake. It was a beautiful creature shining in the late afternoon sun on a pink granite boulder.
Enjoyed every bite of massassauga rattler, though (boys being boys). Used to trade the rattles at school---my more industrious buddies'd stitch the skin onto their belts, looked super-cool. In those days, alls parents used to warn us was that a rattler-head can still bite you after it's cut ff---and not to let the younger kids play with them. Times have sure changed.
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