What is the rattle of a rattlesnake made of?
6451338#11
The most distinctive modification of the snake scale is the "rattle" of rattlesnakes, such as those of the genera "Crotalus" and "Sistrurus". The rattle is made up of a series of loosely linked, interlocking chambers that when shaken, vibrate against one another to create the warning signal of a rattlesnake. Only the bottom is firmly attached to the tip of the tail. 
At birth, a rattlesnake hatchling has only a small button or 'primordial rattle' which is firmly attached to the tip of the tail. The first segment is added when the hatchling sheds its skin for the first time. A new section is added each time the skin is shed until a rattle is formed. The rattle grows as the snake ages but segments are also prone to breaking off and hence the length of a rattle is not a reliable indicator of the age of a snake.
Snake scale
3870228#3
Like other rattlesnakes, "C. molossus" has a rattle composed of keratin on the end of its tail. Each time the snake sheds its skin, a new segment is added to the rattle. They can shed their skin several times a year, and the rattle is fairly fragile and can be broken, so the length of a rattlesnake's rattle is not an accurate measure of its age, unless the terminal button is intact.
Crotalus molossus
458086#22
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) in a behavior known as tail vibration. 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.
Rattlesnake
458086#2
Rattlesnakes receive their name from the rattle located at the end of their tails, which makes a loud rattling noise when vibrated that deters predators or serves as a warning to passers-by. However, rattlesnakes fall prey to hawks, weasels, king snakes, and a variety of other species. Rattlesnakes are heavily preyed upon as neonates, while they are still weak and immature. Large numbers of rattlesnakes are killed by humans. Rattlesnake populations in many areas are severely threatened by habitat destruction, poaching, and extermination campaigns.
Rattlesnake
38076305#17
In a study of the rattling made by rattlesnakes of different species, the Canadian zoologists Brock Fenton and Lawrence Licht found that the sounds are always similar: they have rapid onset (starting suddenly, and reaching full volume in a few milliseconds); they consist of a "broadband" mixture of frequencies between 2 kHz and 20 kHz, with little energy either in the ultrasonic (above 20 kHz) or in the rattlesnakes' hearing range (below 700 Hz); and the frequencies do not change much with time (the rattling after 2 minutes having a similar spectrum to that at onset). There was no clear difference in the sounds made by the different species measured: "Crotalus horridus", "Crotalus adamanteus", "Crotalus atrox", "Crotalus cerastes", "Crotalus viridis" and "Sistrurus catenatus". This pattern implies that the rattling "could serve as a general attention-getting device", which "is designed as a deimatic or startle display". Its similarity to the "broadband, harsh sounds" used as warning calls by birds and mammals may enhance its effectiveness. Since rattlesnakes can barely hear the sound, it is unlikely to serve as any form of communication to other snakes of the same species. Finally, the sounds are not in themselves loud enough to cause pain and hence keep predators away.
Deimatic behaviour
58176764#47
The Rattlesnake is a snake made of 100 rattles who is the A-B-Sea Serpent's companion.
List of Oz characters (post-Baum)
359070#9
Burrowing owls often nest and roost in the burrows made by ground squirrels, a strategy also used by rattlesnakes. When threatened the owl retreats to the burrow and produces rattling and hissing sounds similar to that of a rattlesnake. The behavior is suggested to be an example of acoustic Batesian mimicry and has been observed to be an effective strategy against animals that are familiar with dangers posed by rattlesnakes.
Burrowing owl
5381198#3
Like other rattlesnakes, they have eyes with vertical pupils, and their tail has a rattle on it. The rattle is composed of keratin. Each time the snake sheds its skin, a new segment is added to the rattle, but the rattle is fragile and may break off, and the frequency of shedding can vary, so the snake's age cannot be determined by its length or number of segments.
Crotalus viridis nuntius
52478475#9
Other researchers have suggested that the rattle may have evolved originally to enhance caudal luring, and that caudal luring behavior therefore preceded defensive tail vibration in rattlesnakes. In support of this hypothesis, researchers suggest that a “proto-rattle” would not have increased sound production since rattles require a certain threshold of complexity (at least two overlapping rings of keratin) in order to produce sound. Proponents of this hypothesis suggest that a proto-rattle may have enhanced caudal luring, a behavior common to rattlesnakes and their closest relatives, because such a structure might have looked similar to an arthropod head. Those in support of this hypothesis also point out that specialized keratinized structures have evolved in caudal luring species before, such as in the spider-tailed horned viper, Pseudocerastes urarachnoides.
Tail vibration
458086#23
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.
Rattlesnake