Tail vibration

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Tail vibration is a common behavior in some snakes where the tail is vibrated rapidly as a defensive response to a potential predator. Tail vibration should not be confused with where the tail is twitched in order to attract prey. While rattlesnakes are perhaps the most famous group of snakes to exhibit tail vibration behavior, many other snake groups—particularly those in the Colubridae and Viperidae families—are known to vibrate tails when feeling threatened.

Contents

Description

Process

Tail vibration involves the rapid shaking of the tail in response to a predatory threat. The behavior is particularly widespread among New World species of Viperidae and Colubridae. [1] [2] However, some Typhlopidae and Boidae species may also tail vibrate. [3] [4] At least one species of lizard—Takydromus tachydromoides—has been shown to tail vibrate in response to a potential predator. [5]

Tail vibration behavior in rattlesnakes is somewhat different from tail vibration in other snakes because rattlesnakes hold their tails vertically when tail vibrating, whereas other snakes hold the tail horizontally. Presumably, this is because the rattlesnake rattle produces its own noise, which would be diminished by the exterior of the rattle contacting the ground, and, conversely, snakes without rattles must vibrate the tail against the ground or some other object in order to make noise.

Rattlesnakes tail vibrate with the tail held vertically while other snakes tail vibrate horizontally.

Speed

The speed of tail vibration is directly correlated with temperature, at least for rattlesnakes. The warmer a rattlesnake, the faster it vibrates its tail. [6] Rattlesnakes tail-vibrate faster than other snakes, with some individuals nearing or exceeding 90 rattles per second. [7] [8] This makes rattlesnake tail vibration one of the fastest sustained vertebrate movements—faster than the wingbeat of a hummingbird. The movement is possible thanks to specialized “shaker” muscles in the rattlesnake tail.

Snakes more closely related to rattlesnakes vibrate more quickly than do more distant rattlesnake relatives. [1] In one study that measured tail vibration in 155 snakes representing 56 species, vibratory speed ranged from 9 vibrations per second (Bothriopsis taeniata) to 91 rattles per second (Crotalus polystictus). [1] In the study, only two rattlesnakes (of 33 individuals filmed) had a maximum vibratory rate slower than the fastest non-rattlesnakes. The fastest non-rattlesnakes examined were species of Agkistrodon and New World Colubrids, both of which could sustain vibratory speeds up to about 50 rattles per second.

It is unknown what benefit a snake derives from such fast speeds of tail vibration. One study did find that ground squirrels, Spermophilus beecheyi, are able to ascertain the threat level posed by a rattlesnake based on its rattling speed. [9] Thus, it is possible that fast rattling speeds could be driven by predator-mediated selection, whereby snake predators avoid faster-vibrating individuals.

Function

It is also unknown what the specific function of tail vibration is. Many researchers [2] [4] [10] have posited that it is primarily an auditory aposematic warning signal— like the growling of a wolf or the sound associated with African whistling thorn acacia (Acacia drepanolobium). [11] Others have suggested it could serve as a distraction—particularly for nonvenomous species— meant to draw attention away from a snake’s head and towards its less vulnerable tail. [12]

It has also been suggested that tail-vibrating nonvenomous snakes sympatric with rattlesnakes may be Batesian mimics of rattlesnakes that gain protection from predators by mimicking the rattling sound produced by rattlesnakes (all of which are venomous). In support of this hypothesis, one study found that gophersnake (Pituophis catenifer) populations sympatric with rattlesnakes tail-vibrate for longer durations than island populations allopatric with rattlesnakes. The authors suggest this finding is consistent with the mimicry hypothesis because the behavior appears to be degrading in allopatry, where predators are not under selection to avoid rattlesnake-like behavior. [13] The mimicry hypothesis does not explain why Old World nonvenomous snakes also tail-vibrate, since rattlesnakes are solely a New World taxa, though there are also Old World venomous snakes that tail-vibrate. [1]

Evolution

Tail vibration is widespread among Vipers and Colubrids, and the behavior may be deeply ancestral in both groups.

Tail vibration behavior in rattlesnakes may have evolved from tail vibration in rattle-less ancestors. In support of this hypothesis are studies that show the similarity in specialized tail morphology and rate and duration of tail vibration between rattlesnakes are their closest relatives. [1] [14] The evolution of rattlesnake rattling from simple tail vibration behavior may, in fact, be an example of behavioral plasticity leading to the evolution of a novel phenotype. [1]

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. [15] 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, [1] because such a structure might have looked similar to an arthropod head. [15] 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.

Opponents of the "caudal luring hypothesis" point out the lack of parsimony in such a process, since it would require the behavior to evolve from an offensive to a defensive context (extant rattlesnakes only use the rattle in defensive contexts). [4] [10] [14] If rattlesnake rattling behavior evolved from tail vibration, it would require no such change in behavioral context. Additionally, some have suggested that a proto-rattle could have increased sound production if the modified tail tip increased noise production when vibrated against the substratum. [16]

See also

Related Research Articles

Snake Limbless, scaly, elongate reptile

Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes. Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more joints than their lizard ancestors, enabling them to swallow prey much larger than their heads with their highly mobile jaws. To accommodate their narrow bodies, snakes' paired organs appear one in front of the other instead of side by side, and most have only one functional lung. Some species retain a pelvic girdle with a pair of vestigial claws on either side of the cloaca. Lizards have evolved elongate bodies without limbs or with greatly reduced limbs about twenty-five times independently via convergent evolution, leading to many lineages of legless lizards. These resemble snakes, but several common groups of legless lizards have eyelids and external ears, which snakes lack, although this rule is not universal.

<i>Lachesis</i> (genus) Genus of snakes

Lachesis, also known as bushmasters, is a genus of venomous pit vipers found in forested areas of Central and South America. The generic name refers to one of the Three Fates, Lachesis, in Greek mythology who determined the length of the thread of life. Four species are currently recognized.

Mimicry Imitation of another species for selective advantage

In evolutionary biology, mimicry is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of the same species. Often, mimicry functions to protect a species from predators, making it an anti-predator adaptation. Mimicry evolves if a receiver perceives the similarity between a mimic and a model and as a result changes its behaviour in a way that provides a selective advantage to the mimic. The resemblances that evolve in mimicry can be visual, acoustic, chemical, tactile, or electric, or combinations of these sensory modalities. Mimicry may be to the advantage of both organisms that share a resemblance, in which case it is a form of mutualism; or mimicry can be to the detriment of one, making it parasitic or competitive. The evolutionary convergence between groups is driven by the selective action of a signal-receiver or dupe. Birds, for example, use sight to identify palatable insects and butterflies, whilst avoiding the noxious ones. Over time, palatable insects may evolve to resemble noxious ones, making them mimics and the noxious ones models. In the case of mutualism, sometimes both groups are referred to as "co-mimics". It is often thought that models must be more abundant than mimics, but this is not so. Mimicry may involve numerous species; many harmless species such as hoverflies are Batesian mimics of strongly defended species such as wasps, while many such well-defended species form Müllerian mimicry rings, all resembling each other. Mimicry between prey species and their predators often involves three or more species.

<i>Crotalus cerastes</i> Species of snake

The sidewinder, also known as the horned rattlesnake and sidewinder rattlesnake, is a venomous pit viper species belonging to the genus Crotalus, and is found in the desert regions of the Southwestern United States and northwestern Mexico. Three subspecies are currently recognized.

Rattlesnake Group of venomous snakes of the genera Crotalus and Sistrurus

Rattlesnakes are the venomous snakes forming the genera Crotalus and Sistrurus of the subfamily Crotalinae. All rattlesnakes are vipers. The scientific name Crotalus is derived from the Greek κρόταλον, meaning "castanet". The name Sistrurus is the Latinized form of the Greek word for "tail rattler" and shares its root with the ancient Egyptian musical instrument the sistrum, a type of rattle. The 36 known species of rattlesnakes have between 65 and 70 subspecies, all native to the Americas, ranging from southern Alberta, Saskatchewan, and southern British Columbia in Canada to central Argentina. The largest rattlesnake, the eastern diamondback, can measure up to 8 ft (2.4 m) in length. Rattlesnakes are predators that live in a wide array of habitats, hunting small animals such as birds and rodents.

Fauna of Belize

Belize is a country with a rich variety of wildlife, due to its unique position between North and South America, and a wide range of climates and habitats for plant and animal life. Belize's low human population, and approximately 8,867 square miles (22,970 km2) of undistributed land, provides an ideal home for more than 5000 species of plants, and vast numbers species of animals — with several hundred vertebrates including armadillos, snakes, and monkeys.

Batesian mimicry Bluffing imitation of a strongly defended species

Batesian mimicry is a form of mimicry where a harmless species has evolved to imitate the warning signals of a harmful species directed at a predator of them both. It is named after the English naturalist Henry Walter Bates, after his work on butterflies in the rainforests of Brazil.

<i>Bothrops</i> Genus of snakes

Bothrops is a genus of highly venomous pit vipers endemic to Central and South America. The generic name, Bothrops, is derived from the Greek words βόθρος, bothros, meaning "pit", and ώπς, ops, meaning "eye" or "face", together an allusion to the heat-sensitive loreal pit organs. Members of this genus are responsible for more human deaths in the Americas than any other group of venomous snakes. Currently, 45 species are recognized.

<i>Lachesis muta</i> Species of snake

Lachesis muta, also known as the Southern American bushmaster or Atlantic bushmaster, is a venomous pit viper species found in South America, as well as the island of Trinidad in the Caribbean. Two subspecies are currently recognized, including the nominate subspecies described here.

<i>Pituophis catenifer</i> Species of snake

Pituophis catenifer is a species of nonvenomous colubrid snake endemic to North America. Nine subspecies are currently recognized, including the nominotypical subspecies, Pituophis catenifer catenifer, described here. This snake is often mistaken for the prairie rattlesnake, but can be easily distinguished from a rattlesnake by the lack of black and white banding on its tail and by the shape of its head, which is narrower than a rattlesnake's.

<i>Agkistrodon bilineatus</i> Species of snake

Agkistrodon bilineatus is a highly venomous pit viper species found in Mexico and Central America as far south as Honduras.

Ambush predator Predator that sits and waits for prey to come to it

Ambush predators or sit-and-wait predators are carnivorous animals that capture or trap prey by stealth, luring or by strategies utilizing an element of surprise. Unlike pursuit predators, who chase to capture prey using sheer speed or endurance, ambush predators avoid fatigue by staying in concealment, waiting patiently for the prey to get near, before launching a sudden overwhelming attack that quickly incapacitates and captures the prey.

Aggressive mimicry Deceptive mimicry of a harmless species by a predator

Aggressive mimicry is a form of mimicry in which predators, parasites, or parasitoids share similar signals, using a harmless model, allowing them to avoid being correctly identified by their prey or host. Zoologists have repeatedly compared this strategy to a wolf in sheep's clothing. In its broadest sense, aggressive mimicry could include various types of exploitation, as when an orchid exploits a male insect by mimicking a sexually receptive female, but will here be restricted to forms of exploitation involving feeding. An alternative term Peckhamian mimicry has been suggested, but is seldom used. For example, indigenous Australians who dress up as and imitate kangaroos when hunting would not be considered aggressive mimics, nor would a human angler, though they are undoubtedly practising self-decoration camouflage. Treated separately is molecular mimicry, which shares some similarity; for instance a virus may mimic the molecular properties of its host, allowing it access to its cells.

Caudal luring Form of aggressive mimicry where the predator attracts prey using its tail

Caudal luring is a form of aggressive mimicry characterized by the waving or wriggling of the predator's tail to attract prey. This movement attracts small animals who mistake the tail for a small worm or other small animal. When the animal approaches to prey on the worm-like tail, the predator will strike. This behavior has been recorded in snakes, sharks, and eels.

Seismic communication

Seismic or vibrational communication is a process of conveying information through mechanical (seismic) vibrations of the substrate. The substrate may be the earth, a plant stem or leaf, the surface of a body of water, a spider's web, a honeycomb, or any of the myriad types of soil substrates. Seismic cues are generally conveyed by surface Rayleigh or bending waves generated through vibrations on the substrate, or acoustical waves that couple with the substrate. Vibrational communication is an ancient sensory modality and it is widespread in the animal kingdom where it has evolved several times independently. It has been reported in mammals, birds, reptiles, amphibians, insects, arachnids, crustaceans and nematode worms. Vibrations and other communication channels are not necessarily mutually exclusive, but can be used in multi-modal communication.

Bullsnake Subspecies of reptile

The bullsnake is a large, nonvenomous, colubrid snake. It is a subspecies of the gopher snake. The bullsnake is one of the largest/longest snakes of North America and the United States, reaching lengths up to 8 ft.

Deimatic behaviour Bluffing display of an animal used to startle or scare a predator

Deimatic behaviour or startle display means any pattern of bluffing behaviour in an animal that lacks strong defences, such as suddenly displaying conspicuous eyespots, to scare off or momentarily distract a predator, thus giving the prey animal an opportunity to escape. The term deimatic or dymantic originates from the Greek δειματόω (deimatόo), meaning "to frighten".

Lingual luring

Lingual luring is a form of aggressive mimicry in which a predator uses its tongue to fool potential prey into approaching close to what appears to be a small wriggling worm.

In evolutionary biology, mimicry in vertebrates is mimicry by a vertebrate of some model, deceiving some other animal, the dupe. Mimicry differs from camouflage as it is meant to be seen, while animals use camouflage to remain hidden. Visual, olfactory, auditory, biochemical, and behavioral modalities of mimicry have been documented in vertebrates.

References

  1. 1 2 3 4 5 6 7 Allf, Bradley C., Paul AP Durst, and David W. Pfennig. "Behavioral Plasticity and the Origins of Novelty: The Evolution of the Rattlesnake Rattle." The American Naturalist 188.4 (2016): 475–483
  2. 1 2 Young, Bruce A. "Snake bioacoustics: toward a richer understanding of the behavioral ecology of snakes." The Quarterly review of biology 78.3 (2003): 303–325
  3. ↑ Lazell, James D. “1988. “Typhlops braminus (Brahminy Blind Snake) rattling. Herpetological Review 19.4 (1988): 85
  4. 1 2 3 Greene, Harry W. "Defensive tail display by snakes and amphisbaenians." Journal of Herpetology (1973): 143-161
  5. ↑ Mori, Akira. "Tail vibration of the Japanese grass lizard Takydromus tachydromoides as a tactic against a snake predator." Journal of Ethology 8.2 (1990): 81–88
  6. ↑ Martin, James H., and Roland M. Bagby. "Temperature-frequency relationship of the rattlesnake rattle." Copeia (1972): 482–485
  7. ↑ Allf BC, Durst PAP, Pfennig DW (2016) Data from: Behavioral plasticity and the origins of novelty: the evolution of the rattlesnake rattle. Dryad Digital Repository. https://dx.doi.org/10.5061/dryad.c36k6
  8. ↑ Schaeffer, P. J. K. E., K. Conley, and S. Lindstedt. "Structural correlates of speed and endurance in skeletal muscle: the rattlesnake tailshaker muscle." Journal of experimental Biology 199.2 (1996): 351–358
  9. ↑ Owings, Donald H., Matthew P. Rowe, and Aaron S. Rundus. "The rattling sound of rattlesnakes (Crotalus viridis) as a communicative resource for ground squirrels (Spermophilus beecheyi) and burrowing owls (Athene cunicularia)." Journal of Comparative Psychology 116.2 (2002): 197
  10. 1 2 Klauber, Laurence M. Rattlesnakes. Vol. 1. Univ of California Press, 1956
  11. ↑ Lev-Yadun, Simcha. "Does the whistling thorn acacia (Acacia drepanolobium) use auditory aposematism to deter mammalian herbivores?." Plant Signaling & Behavior 11.8 (2016): e1207035
  12. ↑ Williams, George Christopher. Adaptation and natural selection: a critique of some current evolutionary thought. Princeton University Press, 2008
  13. ↑ Allf, Bradley C., Sparkman, Amanda M., Pfennig, David W. "Microevolutionary change in mimicry? Potential erosion of rattling behaviour among nonvenomous snakes on islands lacking rattlesnakes" Ethology Ecology & Evolution (2020). DOI: 10.1080/03949370.2020.1837962
  14. 1 2 Moon, Brad R. "Muscle Physiology and the Evolution of the Rattling System in Rattlesnakes." Journal of Herpetology (2001): 497–500. Web
  15. 1 2 Schuett, Gordon W., David L. Clark, and Fred Kraus. "Feeding mimicry in the rattlesnake Sistrurus catenatus, with comments on the evolution of the rattle." Animal Behaviour 32.2 (1984): 625–626
  16. ↑ Tiebout, Harry M. "Caudal luring by a temperate colubrid snake, Elaphe obsoleta, and its implications for the evolution of the rattle among rattlesnakes." Journal of Herpetology 31.2 (1997): 290–292
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