From Wikipedia
“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.”
“At birth, a “pre-button” 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.”
My Observation:
It is known that the amount of segments is not an indication of the age of the snake. Furthermore, it is also not a true reflection on the amount of sheds that the snake had as pieces break off.
On the 22de July 2012, a purge two Dusky pigmy rattlesnake (Sistrurus miliarius barbouri)
During a photo session on the 8th October 2012, I noticed a staged shed on the tail on one of them, this was removed by spraying it with water over 2 days and it came off.
Pic 1
From my records, he only shed once (13th Sep 2012) in the period (Jul-Oct) at the time of the photo two segments were noticeable.
At that time, I did not think much and did not pay any further attention.
On the 4th Jan 2013 my Western diamondback (Crotalus atrox) shed in one piece, I had time on hand and cut the shed up and scanned it on a flatbed scanner.
Pic 2 (Chupacabra)
From this scan (Pic 2) it seems if it shed till the first segment.
The following two questions came to mind after reading the statement on Wikipedia:
Question 1: What was retained to form the next rattle?
Question 2: If the snake had a bad shed as in pic 1, will that cause up normalities to that segment?
I then decided to dig out the old photos and compare them with more resent ones.
Pic 3 (Chupacabra): Top view
Pic 4 (Chupacabra): Side view
Pic 3; 4 was taken on the 04th Feb 2012.
Taken from where the body scales end as the first segment, 5 segments are visible in Pic 3 since then three sheds were recorded.
I need to mention that this rattler hardly rattles even during feeding, so the change of a lost segment was not likely but not over seen.
The next photos was taken 11 months later (12th Jan 2013)
Pic 5 (Chupacabra)
Pic 6 (Chupacabra)
In comparison to Pic 3; 4 the end of the body scales is not prominent and does not overlap the first segment.
Does this explain why it seems if he shedded up to the fist segment (Pic 2) and this the reason that only seven segments appear in Pic 5.
The observation was extended to the other Western diamondback. A lack of evidence makes it difficult to compare.
(1) A piece of retained shed that obscure the counting of segments.
(Pic 7) taken 04th Feb 2012 and
(2) no scan copy of the last shed was obtained (25th Dec 2012). Also three sheds was
recorded where the first was 07th Feb 2012, 3 days after the fist photo (Pic 7) was
taken.
Pic 7(Camazotz)
The end of the body scales and the first segment is prominent. The end of the tail appears swollen.
This rattler in comparison with the other doesn’t stop rattling, even when a light is switch on in the room, she will start to rattle.
Pic 8; 9 was taken on the 13th Jan 2013. (Rev 1: 7 segments counted)
Pic 8 (Camazotz)
Pic 9 (Camazotz)
Here the body scales are overlapping the first segment.
Conclusion
More observation is needed to conclude a finer time line but from the above it seems that the last two rows of the tail scales become obscure and appears swollen as the new segment is formed within the tale section, shedding take place and 8-18 days after shedding the tail normalize and the new segment is visible.
Finely:
It is more correct to say:
Shedding is the result of growth and the wellbeing of a reptile and the forming of a segment has to do with growth and not shedding.