The tail rattle is an anatomical formation that occurs exclusively in the species of the rattlesnakes ( Crotalus ) and dwarf rattlesnakes ( Sistrurus ) belonging to the pit otters . It is used by the animals to produce a loud warning sound against potential enemies or other threats.
The tail rattle is formed at the tail end of the rattlesnakes. It is a structure of several loosely nested horn scales. These are former scales of the tip of the tail, which are the only ones that are not shed during the moult; accordingly, the rattle is lengthened with each moult . In the wild, the end links of the rattle occasionally break off, so that the number of end links only corresponds to the previous number of molts in young snakes. However, these shed their skin several times a year, which means that it is not possible to specify the age of the rattle members.
The tail of almost all rattlesnakes is very short compared to other snakes. Since rattlesnakes are ground-living, they do not need a tail to be used when climbing. Also, a short tail can be made to vibrate more easily to use the tail rattle. An exception is the long-tailed rattlesnake ( Crotalus stejnegeri ), which only forms a short tail rattle and only makes the tip of its tail vibrate.
The tail rattle is typically very different in size. Both forest and steppe-dwelling species usually have a relatively large rattle. In contrast, various island populations have only very small rattles and lose the last rattles; the Santa Catalina rattlesnake ( C. catalinensis ) is the only species that does not form a tail rattle.
Use as a warning signal
The main defense strategy of the rattlesnakes is their camouflage through coloration and behavior. In addition, they often hide under stones or in bushes. When this passive defense does not work, an active and aggressive defense occurs, which is mainly used against large mammals. They then curl up on the ground and use their tail rattle to produce a clear warning sound, while fixing the potential opponent and, in extreme cases, biting. The warning from the very loud rattle is particularly effective for ungulates, which tend to come across rattlesnakes by chance and trample them on.
Imitation of rattlesnakes
Since the behavior and above all the warning sound of the rattlesnakes is very effective, especially against unspecialized predators, there are a number of other animals that imitate this sound of the rattle and in this way try to imitate a rattlesnake ( mimicry ). This can be observed above all in various non-poisonous snakes , which are also similar in color to rattlesnakes. These include species of the climbing snake ( Pantherophis ), the bull snake ( Pituophis melanoleucas ) and the western hook- nosed snake ( Heterodon nasicus ). Another unusual feature is the behavior of belonging to the owls Kaninchenkauzes ( Athene cunicularia ), who lives in underground burrows and also mimics the rattle of rattlesnakes at risk.
The sand rattle otters of the genus Echis , which occur mainly in Africa, have developed a similar warning sound independently of the rattlesnakes. With them, the body scales are very rough due to high keels and rubbing against each other creates a loud rattling warning sound. The Asian Halysotter , which has a horn stinger on the underside of its tail, warns in a similar way , which it quickly vibrates across the ground.
- Chris Mattison: Rattlers! A natural history of rattlesnakes. Blandford, London 1996, ISBN 0-7137-2534-6 , pp. 23-27.